JP6065155B2 - Foundation pile construction method, program, storage medium, and foundation pile construction system - Google Patents

Description

The present invention relates to a method and construction of the foundation pile, such as ready-made pile and place pile, program, storage medium, relating to construction systems 及 beauty foundation piles. This application claims priority on the basis of the international patent application PCT / JP2014 / 054542 filed on February 25, 2014 at the Japan Patent Office. By reference to this application, the present application Incorporated.

  As foundation structures for buildings, etc., pile foundations made by burying prefabricated piles such as PHC piles, RC piles, PRC piles, steel piles, SC piles, and node piles in pile holes formed in the ground are often used. . An embedded pile method is known as a method for constructing a pile by building the ready-made pile. The embedded pile method has less noise and vibration than the driven pile method, and is often used particularly in urban areas. The embedded pile method includes a pre-boring method in which a ready-made pile is built in a hole excavated in advance by a drilling device such as an earth auger, and a ground auger is inserted into a hollow ready-made pile, and the ground below the tip of the ready-made pile is There is a medium digging method that builds a ready-made pile in the hole.

  In the embedded pile method, first, a pile hole is excavated and an enlarged excavation part is formed at the bottom of the pile hole, and then a root-setting liquid such as cement milk is injected into the enlarged excavation part, and the tip of the ready-made pile is inserted into the inside. The tip support force is increased by inserting a portion to form a so-called rooted portion. As a construction method of a ready-made pile that forms an enlarged excavation part at the bottom of a pile hole and then forms a root-clamping part, Patent Document 1 includes a pre-boring method, and Patent Document 2 includes a medium-digging method. Each is disclosed. Moreover, in patent document 3, when designing a foundation pile, in order to prevent destruction of the consolidation part at the time of a load action, and to perform load transmission from the tip of a steel pipe pile to a consolidation part effectively, It is disclosed that the expansion ratio of the outer diameter of the solidified portion to the outer diameter of the steel pipe pile is set to be within a predetermined numerical range.

JP 2008-106426 A JP 2006-342560 A JP 2007-032044 A

  However, in the pre-boring method such as the pre-boring method and the digging method, the pre-made pile construction method adapts the ground strength and the bearing capacity of the pre-made pile in the environment where the ground strength is difficult to predict or the ground strength varies widely. There was a problem that it was difficult. In other words, when the load test of a ready-made pile is performed at the actual construction site, if the ground strength is higher than expected, an excessive tip support force can be obtained relative to the design support force of the ready-made pile, so-called overspec It becomes an uneconomical design. On the other hand, when the ground strength is lower than expected, only a tip support force that is too small relative to the design support force can be obtained. Therefore, it is necessary to redesign the pile hole including the enlarged excavation part.

  In particular, when forming an enlarged excavation part that is larger than necessary when forming the root consolidation part, so-called over-specification occurs, and the injection amount of the root compaction liquid and the expansion excavation part for forming the root consolidation part are excavated. The amount of discharged soil is excessively increased, which is not preferable in terms of the cost of materials and the efficiency of construction work. In other words, in the process of constructing ready-made piles, the optimal design of the expansion ratio that shows the ratio of the inner diameter of the enlarged excavation part to the outer diameter of the tip part of the ready-made piles is not to be over-spec when forming the consolidation part. It becomes extremely important. Also, even in the case of cast-in-place piles that are foundation piles, in the process of construction, the inner diameter of the expanded excavation part relative to the effective diameter of the enlarged diameter part at the tip side should be reduced so as not to become overspec when forming the enlarged diameter part. Optimum design of the magnification ratio showing the ratio is extremely important.

  In patent document 1 and patent document 2, although it refers to the construction method which forms an enlarged excavation part using excavation apparatuses, such as an earth auger, and then builds a ready-made pile and forms a solidification part, expansion No reference is made to obtaining the optimum value of the expansion ratio of the excavated part. Moreover, in patent document 3, it mentions regarding setting the expansion ratio of the outer diameter of the solidification part with respect to the outer diameter of a pile so that it may become a predetermined | prescribed numerical range. However, there is no mention about designing an enlarged excavation part by calculating the optimum value of the enlargement ratio based on the ground strength at the actual construction site where the foundation pile is constructed.

The present invention has been made in view of the above problems, and when a foundation pile is provided in a pile hole having an enlarged excavation portion on the bottom side, an economical design of the foundation pile according to the ground strength at the actual construction site and methods construction of foundation piles for setting an enlargement ratio efficiently to allow construction, program, storage medium, and an object thereof is to provide a construction system 及 beauty foundation piles.

  One aspect of the present invention is a construction method of a foundation pile in which a foundation pile is provided in a pile hole in which an enlarged excavation part with an enlarged inner diameter is formed on the bottom side, and an outer diameter design at a predetermined position of a tip portion of the foundation pile From the setting step of setting a plurality of expansion ratios showing different ratios of the inner diameter of the expanded excavation part with respect to the value, and the plurality of expansion ratios set in the setting step at the construction site where the foundation pile is actually provided A design bearing capacity measurement step of measuring a design bearing capacity of the foundation pile at the one or more magnification ratios by performing a loading test on each of the selected one or a plurality of magnification ratio cases, and the design bearing capacity measurement. For each of the one or more design support forces measured in the loading test performed at the construction site in the process, the product of the design support force and the number of foundation piles to be used is the foundation pile. The design support force determination step for determining whether or not the design load is greater than or equal to the desired design load acting on the pile foundation formed by the step, and the design support force of the foundation pile at the one expansion ratio in the design support force measurement step In the case of measuring, the one enlargement ratio is determined as the optimum enlargement ratio for forming the enlarged excavation part when the product satisfies the condition that the product is equal to or greater than the desired design load in the design supporting force determination step. When measuring the design support force of the foundation pile at the plurality of expansion ratios in the design support force measurement step, the condition that the product is equal to or greater than the desired design load in the design support force determination step. An optimum enlargement ratio determining step for determining the optimum enlargement ratio for forming the enlargement excavation part among the enlargement ratios to be satisfied, and an enlargement excavation for forming the enlargement excavation part based on the optimum enlargement ratio Part formation And, as the plurality of expansion ratios in the setting step, at least soil data obtained in advance by ground survey at the construction site where the foundation pile is actually provided, measurement data of the load test described above, and the foundation pile A design value expansion ratio set to an optimum value based on predetermined data including past construction performance data, an upper side expansion ratio obtained by adding a predetermined value to the design value expansion ratio, and a predetermined value based on the design value expansion ratio A lower magnification ratio obtained by subtracting the value of is set.

  According to one aspect of the present invention, the optimum value of the enlargement ratio can be calculated based on the result of the loading test performed at the actual construction site and the information on the result of the ground survey conducted in advance at the construction site. For this reason, the optimal expansion ratio which enables the economical design of the foundation pile according to ground strength can be set efficiently. Thereby, the overspec at the time of forming an expanded excavation part can be reduced. Specifically, at the construction site where the foundation pile is actually installed, a loading test is carried out in the design bearing capacity measurement process to obtain the design bearing capacity, and the design bearing capacity determination process and the optimum expansion ratio are determined based on the design bearing capacity. Designed without changing the specifications of the ready-made piles (pile type, pile diameter D, pile length L, material strength, etc.) that were initially set by implementing the process and setting the minimum enlargement ratio as the optimum expansion ratio The bearing capacity can be determined. In addition, since the optimum enlargement ratio can be set with as few loading tests as possible, it is possible to reduce the labor and test period of the loading test. Thereby, economic efficiency can further be improved. Furthermore, when applied to a ready-made pile, the ready-made pile is constructed by an embedding method such as a pre-boring method or a digging method, so that it does not stop at a high level and can be reliably constructed at a design depth position. Furthermore, the validity of the design value enlargement ratio set in the setting process can be further examined, including the lower enlargement ratio that is smaller than the design value enlargement ratio and the upper enlargement ratio that is a larger enlargement ratio. Moreover, if construction is performed at the lower expansion ratio, not only the construction efficiency is increased, but also the amount of excavation and the amount of curable material used can be reduced, and the specifications of construction equipment can be suppressed. Furthermore, if the construction is performed at the upper magnification ratio, the amount of excavation and the amount of the curable material used for hardening the tip will increase, but safer design and construction will be possible. In addition, as the plurality of enlargement ratios set to form the enlarged excavation part, the design enlargement ratio that is the optimum value is taken as the reference value, and the upper and lower values are taken. Therefore, the upper and lower limits of the enlargement ratio are affected. Absent.

  At this time, in one aspect of the present invention, the setting step sets at least the design value magnification ratio, the upper magnification ratio, and the lower side based on the predetermined data when setting the plurality of magnification ratios. A step of respectively setting a safety factor and a design support force with respect to an enlargement ratio, and integrating the design support force and the safety factor corresponding to the design value enlargement ratio, the upper enlargement ratio, and the lower enlargement ratio, It is good also as including the process of calculating each ultimate support force of a pile, and the process of calculating the said design value expansion ratio, the said upper side expansion ratio, and the said lower side expansion ratio which satisfy | fill the said ultimate support force, respectively.

  In one aspect of the present invention, in the setting step, a ratio between a design support force calculated by a predetermined formula and a design support force measured by the load test described above when setting the plurality of enlargement ratios. The design value enlargement ratio, the upper enlargement ratio, and the lower enlargement ratio may be calculated accordingly.

  In one aspect of the present invention, in the design support force determination step, a product of the design support force measured based on the design value expansion ratio and the number of foundation piles is equal to or greater than the desired design load. When the product is equal to or greater than the desired design load in the design support force determination step, at least the design support force measured in the design support force measurement step and the setting step Calculating the difference with the design support force calculated for the design value enlargement ratio set in the above, and predicting design support by correcting the magnitude of the difference with respect to the design support force calculated for the lower enlargement ratio A predicted design support force estimation step for estimating force, and the predicted design support force calculated in the predicted design support force estimation step is measured based on the design value expansion ratio in the design support force measurement step design A prediction design supporting force determination step of determining whether greater or not than lifting force, may further include a.

  In this way, when the loading test is performed at the lower magnification ratio, the product of the number of foundation piles and the design support force is more likely to satisfy the desired design load or higher. It is possible to reliably set a more suitable optimum enlargement ratio after further examining the validity of the designed value enlargement ratio.

  Moreover, in one aspect of the present invention, in the design support force determination step, a product of the design support force measured for each of the plurality of enlargement ratios in the support force measurement step and the number of the foundation piles, Whether or not the load is greater than or equal to the desired design load may be determined in order from the smallest of the plurality of enlargement ratios.

  In this way, it is possible to set the optimum enlargement ratio that does not cause over-specification more efficiently and reliably.

  Moreover, in one aspect of the present invention, the foundation pile is a ready-made pile that is built into the pile hole, and in the design process, the outer diameter of the convex portion provided on the outer peripheral surface of the tip portion of the ready-made pile. It is good also as calculating | requiring the said outer-diameter design value by adding a desired clearance value.

  If it does in this way, the integrity with a root hardening part can be improved. In particular, it is possible to reduce over-specification and high stoppage when constructing a joint pile having a convex portion provided on the outer peripheral surface of the tip of the ready-made pile.

  Moreover, in one aspect of the present invention, the foundation pile is a cast-in-place pile in which a diameter-expanded portion is provided at a distal end portion of the shaft portion that is driven into the pile hole, and in the design process, the shaft portion The outer diameter may be set as the outer diameter design value.

  If it does in this way, the over specification at the time of constructing a cast-in-place pile can be reduced reliably.

  Moreover, the other aspect of this invention is a program for making a computer perform the construction method of the foundation pile in any one mentioned above.

  According to the other aspect of this invention, the optimal expansion ratio of the expansion excavation part formed in the bottom part side of a pile hole can be set in such a small number of loading tests as possible according to this program.

  Moreover, the other aspect of this invention is the storage medium which memorize | stored the program for making a computer perform the construction method of the foundation pile in any one mentioned above so that the said computer could read.

  According to the other aspect of the present invention, the optimum expansion ratio of the expanded excavation part formed on the bottom side of the pile hole can be set in the loading test as few times as possible according to the program stored in the storage medium. .

  Another aspect of the present invention is a foundation pile construction system in which a foundation pile is provided in a pile hole in which an enlarged excavation portion having an enlarged inner diameter is formed on the bottom side, and at least in the construction site where the foundation pile is provided Storage unit for storing predetermined data including soil data obtained in advance by ground survey, measurement data of loading test carried out at the construction site, and past construction performance data of the foundation pile as a database, at least the above A calculation unit that calculates the ratio of the inner diameter of the expanded excavation part with respect to the outer diameter design value at a predetermined position of the tip of the foundation pile based on the predetermined data, and calculates the ratio A design value expansion ratio that is set to an optimum value based on at least the predetermined data and is set to an optimum value based on the predetermined data; and An upper magnification ratio obtained by adding a predetermined value to a ratio; a setting unit configured to set a plurality of values different from a lower magnification ratio obtained by subtracting a predetermined value from the design value magnification ratio; and the calculation unit. The product of the design support force measured by the load test of the case of one or a plurality of enlargement ratios selected from the plurality of enlargement ratios set in step 4 is formed by the foundation piles. A determination unit for determining whether or not the design load is greater than or equal to a desired design load acting on the pile foundation to be measured, and when the design support force at the one expansion ratio is measured in the load test described above Determines the one enlargement ratio as an optimum enlargement ratio for forming the enlarged excavation part when the product satisfies a condition that the product is equal to or greater than the desired design load, and the plurality of enlargement ratios in the load test described above Measure the design bearing capacity at In this case, at least the determination unit determines to determine the minimum expansion ratio among the expansion ratios that satisfy the condition that the product is equal to or greater than the desired design load as the optimal expansion ratio for forming the expanded excavation unit. And a section.

  According to another aspect of the present invention, based on the result of the loading test performed at the actual construction site and the information on the result of the ground survey conducted in advance at the construction site, the bottom of the pile hole can be obtained with as few loading tests as possible. It is possible to set an optimum enlargement ratio of the enlarged excavation portion formed on the side. For this reason, it is possible to efficiently reduce the overspec and the high stop when the enlarged excavation part is formed. Moreover, the expansion excavation part based on the optimal expansion ratio more suitable for the actual ground can be formed by setting the optimal expansion ratio based on the predetermined data concerning construction of the foundation pile.

  As described above, according to the present invention, when a foundation pile is provided in a pile hole in which an enlarged excavation part with an enlarged inner diameter is formed on the bottom side, the economics of the foundation pile according to the ground strength at the actual construction site is provided. The expansion ratio that enables easy design and construction can be set efficiently. In addition, according to the present invention, when an off-the-shelf pile is constructed as a foundation pile, it is constructed by an embedding method such as a pre-boring method or a medium digging method, so that it is reliably constructed at a design depth position without high stopping. be able to. Furthermore, according to this invention, when providing a foundation pile in a pile hole, the optimal expansion ratio of the expansion excavation part formed in the bottom part side of a pile hole can be set by the load test as few times as possible.

Drawing 1 is a schematic structure figure showing a part of pile foundation formed with a ready-made pile built with a construction method of a foundation pile concerning one embodiment of the present invention. FIG. 2 is a block diagram showing an overall configuration of a foundation pile construction system according to an embodiment of the present invention. FIG. 3 is a flowchart showing an outline of a construction method of a foundation pile according to one embodiment of the present invention. FIG. 4 is a graph showing the relationship between the calculated value of the design support force of the foundation pile and the measured value of the design support force in the foundation pile construction method according to one embodiment of the present invention. FIG. 5 is a flowchart showing details of a foundation pile construction method according to an embodiment of the present invention. FIG. 6 is a flowchart showing details of a modification of the foundation pile construction method according to one embodiment of the present invention. FIG. 7 is a flow chart showing details of a foundation pile construction method according to another embodiment of the present invention. FIG. 8: is a flowchart which shows the detail of the modification of the construction method of the foundation pile which concerns on other one Embodiment of this invention. FIG. 9: is a schematic block diagram which shows a part of pile foundation formed with the cast-in-place pile provided with the construction method of the foundation pile which concerns on other one Embodiment of this invention. FIG. 10: is a schematic block diagram of the other modification of the cast-in-place pile provided with the construction method of the foundation pile which concerns on other one Embodiment of this invention. FIG. 11: is a schematic block diagram of the other modification of the cast-in-place pile provided with the construction method of the foundation pile which concerns on other one Embodiment of this invention. FIG. 12: is a schematic block diagram of the other modification of the cast-in-place pile provided with the construction method of the foundation pile which concerns on other one Embodiment of this invention.

  Hereinafter, preferred embodiments of the present invention will be described in detail. The present embodiment described below does not unduly limit the contents of the present invention described in the claims, and all the configurations described in the present embodiment are essential as means for solving the present invention. Not necessarily.

(First embodiment)
First, the outline of the structure of the ready-made pile built with the construction method of the foundation pile which concerns on one Embodiment of this invention, and the pile foundation formed with the said ready-made pile is demonstrated, using drawing. Drawing 1 is a schematic structure figure showing a part of pile foundation formed with a ready-made pile built with a construction method of a foundation pile concerning one embodiment of the present invention. In addition, FIG. 1 is a figure which shows the structure of the front-end | tip solidified part of the ready-made pile especially constructed | assembled by the pre-boring method among the construction methods of the foundation pile which concerns on this embodiment.

  As shown in FIG. 1, the pile foundation 1 is formed by a ready-made pile 10 built in a pile hole 3 excavated at a predetermined position of the ground GN. That is, a plurality of pile holes 3 are excavated at a predetermined position of the ground GN, and ready-made piles 10 are respectively built in the respective pile holes 3, and the pile foundation 1 is formed by these ready-made piles 10. In this embodiment, as the ready-made pile 10, a node pile in which a plurality of convex portions 12 are provided on the outer peripheral surface 10b of the distal end portion 10a is built. In addition, in the construction method which concerns on this embodiment, the ready-made pile 10 used as construction object is not limited to a node pile, It is applicable also to other ready-made piles, such as a straight pile.

  Moreover, in order to ensure the front end support force, the root hardening part 14 is provided in the front end side of the ready-made pile 10. FIG. The root hardening part 14 injects cement milk used as a hardening material into the bottom side of the pile hole 3 and then agitates and mixes with excavated soil to form a soil cement. It is formed by sinking and solidifying and integrating the soil cement. In the present embodiment, the root consolidation portion 14 has an enlarged bulb shape in which the outer diameter is larger than the inner diameter of the upper portion of the pile hole 3 in order to ensure a larger tip support force. In order to form such an enlarged bulb-shaped root consolidation part 14, an enlarged excavation part 5 having an enlarged inner diameter is formed on the bottom side of the pile hole 3.

  In the present embodiment, as shown in FIG. 1, the outer diameter De of the distal root consolidation part 14 is substantially the same as the inner diameter De of the enlarged excavation part 5. Then, the axial length Ld of the tip rooting portion 14 is shorter than the extended excavation portion length Lω which is the axial length of the enlarged excavation portion 5. Specifically, the axial length of the expanded excavation section length Lω is 2 m or more and 50% or less of the pile length of the ready-made pile 10 to be built in the pile hole 3, and the axial length of the tip consolidation part 14 Ld is a larger value of either 2 m or the outer diameter De of the tip root fixing portion 14. The length Ld of the root hardening part 14 may be substantially the same as the expanded excavation part length Lω.

  Moreover, in order to ensure the desired tip supporting force of the ready-made pile 10, in order to form the outer diameter De of the root-solidified portion 14 with respect to the outer diameter Don of the tip portion 10a of the ready-made pile 10, that is, to form the root-solidified portion 14. It is necessary to adjust the enlargement ratio ω indicating the ratio of the inner diameter De of the enlarged excavation part 5 to be excavated. The expansion ratio ω is set to a design value based on predetermined data relating to the construction of the ready-made pile 10 such as a preliminary geological survey result, statistical data, and past construction data performed before the construction of the ready-made pile 10. However, when excavating the pile hole 3 at the actual construction site, the geological structure and soil quality of the ground GN may differ from the previous survey results, and when the ready-made pile 10 is constructed with the set value of the expansion ratio ω as it is , May cause over-spec or high-stop.

  In this way, the ground strength and support of the ready-made piles 10 in an environment where the ground structure and soil quality of the ground GN at the actual construction site are different from the previous survey results, or where the ground strength is difficult to predict or where the ground strength varies widely. Difficult to adapt forces. That is, when the ready-made pile 10 is constructed, the geological condition of the ground GN at the actual construction site is determined, the appropriate depth L of the pile hole 3, the enlargement ratio ω of the enlarged excavation part 5, and the enlarged excavation part length Lω. Must be set to the optimum value.

  In particular, the expansion ratio ω of the expanded excavation portion 5 is a value that determines the outer diameter De of the root consolidation portion 14, and when the error between the design value obtained in advance and the actual measurement value at the actual construction site is large, This is a so-called overspec, which is not preferable in terms of the cost of materials and the efficiency of construction work. That is, in order to secure the desired tip support force of the ready-made pile 10, the length Ld of the root-solidifying portion 14 can be adjusted as appropriate by adjusting the amount of cement milk that becomes a hardening agent.

  However, since the outer diameter De of the root consolidation part 14 is directly determined by the inner diameter De of the excavation part 5, it is difficult to adjust the enlarged excavation part 5 after excavation. In other words, it is extremely important to obtain the optimum value of the enlargement ratio ω of the enlarged excavation part 5 in order to ensure the desired tip support force of the ready-made pile 10 without over-spec. Further, in order to obtain the optimum value of the enlargement ratio ω, it is important to efficiently obtain the optimum value based on the result of a loading test on the ground GN that is an actual construction site.

  For this reason, in this embodiment, the construction method of the foundation pile by the construction system 100 (refer FIG. 2) demonstrated below is implemented, and based on the measured value in an actual construction site, more efficiently and reliably expansion ratio (omega) The over spec is reduced by finding the optimum value of. Moreover, the over-spec and high stop at the time of building ready-made pile 10 in ground GN are suppressed, the cost at the time of constructing the pile foundation 1 which consists of the said ready-made pile 10 is reduced, and the efficiency of construction work is improved. I am doing so.

Further, in the present embodiment, the expansion ratio ω of the root consolidation portion 14, that is, the expansion ratio ω of the expansion excavation portion 5, is set to a desired value for the inner diameter De of the expansion excavation portion 5 and the outer diameter Don of the convex portion 12 of the ready-made pile 10. The outer diameter design value Ds (Ds = Don + x) obtained by adding the clearance value x is defined by the following equation (1).
ω = De / Ds (1)

  In the present embodiment, the enlargement ratio ω is set, for example, in the range of 1.0 to 2.0, but the upper limit value of the enlargement ratio ω is not limited to 2.0. Further, in the present embodiment, in order to obtain a more suitable enlargement ratio ω of the enlarged excavation part 5 in consideration of design errors of the ready-made pile 10, the pile hole 3, and the enlarged excavation part 5, the above formula (1) For the denominator, not the value of the outer diameter Don of the tip 10a of the ready-made pile 10, but the outer diameter design value Ds obtained by adding the desired clearance value x as an adjustment value to the outer diameter Don is used. That is, in this embodiment, the outer diameter Don of the convex part 12 provided in the front-end | tip part 10a of the ready-made pile 10 is used as the outer-diameter design value Ds in the predetermined position of the front-end | tip part 10a of the ready-made pile 10 used for calculation of expansion ratio (omega). A value obtained by adding a desired clearance value x to the above is used.

  The clearance value x is appropriately determined based on N data indicating the strength of the ground on which the ready-made pile 10 is to be constructed, and predetermined data relating to construction such as past construction data and soil data. For example, when the outer diameter Don of the tip portion 10a of the ready-made pile 10 is 1.0 m, the clearance value x is 0.05 m to 0.1 m. The clearance value x may be 0 depending on the N value or the like. The clearance value x is 0.2 m at the maximum. Furthermore, in this embodiment, as shown in FIG. 1, since the joint pile is used as the ready-made pile 10, the outer diameter of the convex portion 12 is used as the outer diameter Don of the ready-made pile 10. When the pile 10 is a straight pile, the outer diameter of the shaft portion of the straight pile is used.

  Next, the structure of the construction system of the foundation pile which concerns on the 1st Embodiment of this invention is demonstrated, using drawing. FIG. 2 is a block diagram showing an overall configuration of a foundation pile construction system according to an embodiment of the present invention. In addition, in FIG. 2, although the case where it applies to a ready-made pile as a foundation pile provided in a pile hole is demonstrated, when the foundation pile construction system which concerns on this embodiment places a cast-in-place pile in a pile hole, Is also applicable.

  As shown in FIG. 2, the foundation pile construction system 100 according to the present embodiment accesses and searches a database server having a database in which a computer 101 held by a user stores predetermined data relating to construction of the ready-made pile 10. While performing the process, the optimum value of the enlargement ratio ω of the enlarged excavation section 5 is obtained. In the present specification, “user” refers to a person who designs or constructs foundation piles such as ready-made piles 10 or the like. The “computer” refers to an information terminal device including an arithmetic device capable of various arithmetic processes such as a super computer, a general-purpose computer, an office computer, a control computer, a personal computer, and a portable information terminal.

  The construction system 100 according to the present embodiment is used when the ready-made pile 10 is built in the pile hole 3 in which the enlarged excavation portion 5 having an enlarged inner diameter is formed on the bottom side, and the computer 101, the design support force measuring device 128, And a drilling device 130. The construction system 100 calculates the optimum enlargement ratio ω by the computer 101 based on the measurement data of the design support force measuring device 128 at the actual construction site where the ready-made pile 10 is built, and based on the enlargement ratio ω. The excavator 130 excavates the pile hole 3 having the enlarged excavation part 5. In addition, the structure of the construction system 100 is not limited to FIG. 2, A various deformation | transformation implementation, such as abbreviate | omitting a part of the component or adding another component, is possible.

  As shown in FIG. 2, the computer 101 includes a storage unit 102, a CPU (Central Processing Unit) 110, an input unit 120, an output unit 122, a communication unit 124, a ROM (Read Only Memory) 108, and a RAM (Random access Memory) 106. , And a storage medium 104, and these components are electrically connected to each other via a system bus 125. Therefore, the CPU 110 accesses the storage unit 102, ROM 108, RAM 106, and storage medium 104, grasps the operation state of the input unit 120, outputs data to the output unit 122, and transmits / receives various information to / from the Internet 126 via the communication unit 124. Etc.

  The memory | storage part 102 is a data server which has a function which memorize | stores the predetermined data which concerns on construction of foundation piles, such as the ready-made pile 10, at least. In the present embodiment, the storage unit 102 includes, as the predetermined data, soil data, pile materials, and construction specifications of the ground GN at an actual construction site where at least the ready-made pile 10 and the cast-in-place pile 20 (see FIG. 9) are provided. Measurement data obtained by performing a load test using the design support force measuring device 128 at an actual construction site and past construction performance data of the ready-made pile 10 are stored in a database.

  Based on the predetermined data related to the construction of such ready-made piles, by setting the optimum expansion ratio ω of the expanded excavation part 5, the geology including the stratum configuration information, soil information, etc. in the ground GN of the actual construction site The enlarged excavation part 5 can be formed at a suitable optimum enlargement ratio ω based on data and the like. In addition, by accumulating these data in the storage unit 102, when the ready-made pile 10 is built in another construction site, the expansion ratio of the expanded excavation unit 5 is utilized using the accumulated data stored in the storage unit 102. The optimum values of ω and the expanded excavation length Lω can be obtained with higher accuracy.

  The CPU 110 has a function of controlling the operation of each component included in the construction system 100 in accordance with data received via the communication unit 124 and various programs stored in the ROM 108 and the storage medium 104. In addition, the CPU 110 has a function of appropriately storing necessary data and the like in the RAM 106 that temporarily stores these various processes.

  In the present embodiment, the CPU 110 performs arithmetic processing by a computer based on predetermined data relating to the construction of the ready-made pile 10 and performs various arithmetic processes necessary for obtaining the expansion ratio ω of the expanded excavation section 5. Function as. That is, the CPU 110 performs an arithmetic process on the computer 101 based on at least the predetermined data, and shows the ratio of the inner diameter De of the expanded excavation portion 5 to the outer diameter design value Ds at a predetermined position of the tip portion 10a of the ready-made pile 10. It has a function for obtaining the ratio ω. Specifically, the CPU 110 enlarges the ratio of the inner diameter De of the expanded excavation portion 5 to the outer diameter design value Ds obtained by adding the desired clearance value x to the outer diameter Don of the tip portion 10a of the ready-made pile 10. It has a function for obtaining ω.

  In the present embodiment, the CPU 110 includes a setting unit 112, a determination unit 114, and a determination unit 116. In the present specification, “predetermined data” relating to the construction of the ready-made pile 10 is the soil data of the ground GN obtained in advance by a geological survey at least at the actual construction site where the ready-made pile 10 is built, It refers to various data such as measurement data of a loading test by the design support force measuring device 128 carried out at the construction site and past construction performance data of the ready-made pile 10. That is, the “predetermined data” means that in the process of constructing the ready-made pile 10, when excavating the pile hole 3 having the enlarged excavation part 5, the optimum expansion ratio ω and the enlarged excavation part length Lω of the enlarged excavation part 5 It refers to various data necessary to determine the values ωopt and Lωopt, and is also used to determine the pile type.

  In the process of constructing the ready-made pile 10 in the construction system 100, the setting unit 112 is based on predetermined data relating to the construction of the ready-made pile 10, and the design load (column load) P of the ready-made pile 10 and the design support force of the pile. R, the expansion ratio ω of the expanded excavation section 5, the function of calculating various data that requires setting such as the expanded excavation section length Lω. In the present embodiment, the setting unit 112 has a function of setting a plurality of expansion ratios ω of the expanded excavation unit 5 with different values based on at least predetermined data relating to the construction of the ready-made pile 10. Specifically, the setting unit 112 adds a predetermined value to the design value expansion ratio and the design value expansion ratio, which is the optimum value, as the expansion ratio based on predetermined data relating to the construction of the foundation pile. It has a function of setting a plurality of values with different values from the upper magnification ratio and the lower magnification ratio obtained by subtracting a predetermined value from the design value magnification ratio. Moreover, in this embodiment, it has a function which sets multiple expansion excavation part length Lomega corresponding to expansion ratio (omega).

  The determination unit 114 has a function of determining the validity of various data set based on predetermined data related to the construction of the ready-made pile 10 in the process of constructing the ready-made pile 10 with the construction system 100. In the present embodiment, the determination unit 114 calculates the product of at least the design support force R measured by the design support force measuring device 128 and the design support force R and the number of ready-made piles 10 to be used as the foundation pile. However, it has the function to determine whether it is more than the desired design load (column load) P which acts on the pile foundation 1 formed by the ready-made pile 10.

  The determination unit 116 has a function of determining optimum values of various data set based on predetermined data related to the construction of the ready-made pile 10 based on the determination result in the determination unit 114. In the present embodiment, when the determination unit 116 measures the design support force R at a plurality of enlargement ratios ω in the loading test, at least the determination unit 114 calculates the product of the design support force R and the number J of ready-made piles 10. Among the expansion ratios ω that satisfy a condition that is equal to or greater than the desired design load (column load) P, the minimum expansion ratio ω is determined as the optimum expansion ratio ωopt for forming the expanded excavation portion 5. In addition, when the determination unit 116 measures the design support force R at one enlargement ratio ω in the loading test, the condition that the product of the design support force R and the number J of ready-made piles 10 is equal to or greater than the desired design load. Has the function of determining the one enlargement ratio ω as the optimum enlargement ratio ωopt for forming the enlarged excavation portion 5 when the above condition is satisfied. Furthermore, in the present embodiment, the determination unit 116 has a function of determining the optimum enlarged excavation unit length Lωopt corresponding to the optimum enlargement ratio ωopt.

  The input unit 120 has a function of inputting various data such as predetermined data related to the construction of the ready-made pile 10, and for example, a mouse, a keyboard, a touch panel, or the like is used. In the present embodiment, the input unit 120 performs, for example, character input when operating the setting unit 112, the determination unit 114, and the determination unit 116 and input of measurement data of the design support force measuring device 128. Further, in the present embodiment, the input unit 120 is necessary when obtaining the optimum values ωopt and Lωopt of the enlarged excavation part 5 and the enlarged excavation part length Lω based on at least predetermined data relating to the construction of the ready-made pile 10. It is also used when inputting various data. That is, the input unit 120 is used when inputting various data stored in the storage unit 102 or when inputting various data for obtaining the optimum values ωopt and Lωopt of the enlargement ratio ω and the enlarged excavation part length Lω. .

  The output unit 122 has a function of outputting a calculation result by the CPU 110, information on the storage unit 102 serving as a database, and the like. For example, a display monitor or the like is used as the output unit 122. In the present embodiment, the output unit 122 performs screen display when the setting unit 112, the determination unit 114, and the determination unit 116 are operated, for example.

  The storage medium 104 is a medium readable by the computer 101 and has a function of storing programs, data, and the like. The function of the storage medium 104 can be realized by various memories such as an optical disk (CD, DVD), HDD, or USB. In the storage medium 104, a program for realizing the function of each component of the construction system 100 according to the present embodiment is stored so as to be readable by the computer 101. For this reason, according to the said program, each process in the construction method of the ready-made pile 10 which concerns on this embodiment comes to be performed by implement | achieving the function of each component of the said construction system 100. FIG. In addition, the detail of the construction method of the ready-made pile 10 which concerns on this embodiment performed by the said program is mentioned later.

  The design support force measuring device 128 constructs a test-made pile 10 '(hereinafter referred to as a test pile 10') in a test-pile hole 3 'formed in the ground GN in an actual construction site where the ready-made pile 10 is built. Then, the loading test is performed, and the ultimate supporting force of the test pile 10 'is measured. In the present embodiment, the design support force measuring device 128 performs a loading test on an actual construction site for each case of one or a plurality of magnification ratios ω selected from a plurality of magnification ratios ω set by the setting unit 112. To measure the ultimate bearing force of the ready-made pile 10 at the one or more enlargement ratios ω.

  Specifically, the design support force measuring device 128 performs a loading test of the test pile 10 ′ corresponding to the case of one or a plurality of enlargement ratios ω selected from the plurality of enlargement ratios ω set by the setting unit 112. It is carried out at the construction site where the ready-made pile 10 is actually built, and the ultimate bearing capacity of the test pile 10 'is measured. Further, the design bearing capacity measuring device 128 is a ground for constructing the ready-made pile 10 when the test pile hole 3 'is drilled before the ready-made pile 10 is constructed in the process of measuring the ultimate bearing capacity of the test pile 10'. It is also used to check GN geological data and N value. The design support force measuring device 128 may be referred to as a loading test device.

  The excavator 130 has a function of excavating a pile hole 3 having a desired diameter and depth in the ground GN. As the excavator 130, an earth auger or the like provided with a excavating rod 131 provided with a screw-like excavating blade 132 around it and a movable excavating portion 134 that can be expanded in the outer diameter direction on the distal end side of the excavating rod 131 is used. The In this embodiment, when excavating the pile hole 3 with the excavator 130, the optimum enlargement ratio ωopt of the enlarged excavation unit 5 determined by the determination unit 116 of the CPU 110 and the optimum enlarged excavation part length Lωopt of the enlarged excavation unit 5 are used. Thus, the enlarged excavation part 5 is formed.

  As described above, according to the construction system 100 of the present embodiment, the pile hole is subjected to as few loading tests as possible while reflecting the analysis results of the test data of the loading test performed at the construction site where the ready-made pile 10 is actually built. 3 can be set to an optimum enlargement ratio ωopt of the enlarged excavation part 5 formed on the bottom side of the figure 3. For this reason, in the process of constructing the ready-made pile 10, it is possible to efficiently and economically reduce the overspec and high stop when the expanded excavation part 5 is formed after adapting to the ground strength at the actual construction site.

  Also, after setting a plurality of enlargement ratios ω, do not unnecessarily increase the number of loading tests performed when determining the optimum value ωopt from among these enlargement ratios ω, that is, with fewer loading tests. The optimum value ωopt can be determined. For this reason, the labor, time, and cost cost in constructing the ready-made pile 10 can be reduced by reducing the number of loading tests that require a large burden both in terms of time and cost. Economical ready-made pile 10 can be designed and constructed.

  Next, the outline of the construction method of the foundation pile which concerns on one Embodiment of this invention is demonstrated, using drawing. FIG. 3 is a flowchart showing an outline of a construction method of a foundation pile according to one embodiment of the present invention.

  The construction method of the foundation pile which concerns on one Embodiment of this invention is the ready-made pile 10 which builds the ready-made pile 10 in the pile hole 3 in which the enlarged excavation part 5 which expanded the internal diameter was formed in the bottom part as shown in FIG. In the construction process, in particular, based on the measurement result of the loading test carried out at the construction site where the ready-made pile 10 is actually built in the pile hole 3, the optimum enlargement ratio ωopt of the expansion excavation part 5 is more suitable. Is placed. In addition, in FIG. 3, although the case where it applies to the ready-made pile 10 as a foundation pile provided in the pile hole 3 is demonstrated, the construction method of the foundation pile which concerns on this embodiment is applicable also to the construction of a cast-in-place pile. is there.

First, a design load (column load) P is set (step S10). The design load (column load) P is set to a desired size based on the weight of the building built on the pile foundation 1, the upper load, and the like. Next, the design support force R and the pile number J of the ready-made pile 10 are set (step S11). The design support force R and the number J of piles of the ready-made pile 10 are set so as to satisfy the following conditional expression (2).
Number of piles J x Design capacity of pile R ≥ Margin M x Design load (column load) P ... (2)

The design support force R of the pile is calculated from the following equation (3), for example.
Design bearing capacity R = 1 / μ × {αNaAp + (β · Ns · Ls + γ · q _u · Lc) · Φ} (3)

In the above formula (3), μ is the safety factor, α is the pile tip bearing capacity coefficient, Na is the average value of the N value at the tip of the pile, Ap is the pile tip area, β is the pile circumference in sandy and gravelly ground. Coefficient of surface friction, Ns is the average value of N of sandy ground around the pile, Ls is the total length of the ground around the pile that touches the sandy and gravelly ground, and γ is in the clayey ground The coefficient of frictional force around the pile surface, q _u is the average uniaxial compressive strength of the clay ground out of the ground around the pile, Lc is the total length of the ground around the pile that touches the clay ground, and Φ is the pile Indicates the circumference. In addition, the design support force R of the pile calculated from the above formula (3) is hereinafter referred to as a calculated value of the design support force R.

  In addition, the calculated value of pile design bearing capacity R and the number of piles J are approximately the same as the design load (column load) P, and the optimum combination of the calculated value of design bearing capacity R per pile and the number of piles J Set as follows. Basically, the calculated value of design bearing capacity R of piles and the number of piles J are set so as to reduce the number of piles J, but the most effective (economic) number of piles J for each column in comparison with the cost etc. And set the calculated value of design bearing capacity R of pile. The margin M indicating the margin is determined by design conditions and the like, but is usually a value of 1 or more, and generally a value of about 1.1 is used, but is limited to M = 1.1. Is not to be done.

  Below, an example of each value which comprises the right side of Formula (3) is shown. In addition, the value shown below is an example and is not limited to this value.

  The safety factor μ is a value that is appropriately determined based on design conditions and the like, and is 2, 2.5, or 3, for example.

In the case of sandy ground and gravelly ground, the pile tip bearing capacity coefficient α is calculated from the following equation (4) using, for example, the expansion ratio ω.
α = 240ω ^1.5 + 90ω …… (4)

Moreover, in the case of a clayey ground, it calculates from the formula (5) shown below, for example.
α = 210ω ^1.25 + 90ω …… (5)

The average value Na of the N values at the pile tip is calculated from the following formula (6) when the pile tip ground is sandy ground or gravelly ground.
Na = (Nu + 3N _L ) / 4 (6)

However, Na is set to 3 or more, and Na> 60 when Na> 60. Here, Nu represented by the above formula (6) is an average value of N values from the tip of the pile to the position of 2 m upward, and _NL is from the tip of the pile to the position of (De + Don) downward. It is an average value of N values.

On the other hand, the average value Na of the pile tip is calculated from the following formula (7) when the pile tip ground is clayey ground.
Na = (Nu + 2N _L ) / 3 (7)

  However, when Na> 58.3, the Na is not calculated by the above equation (7), and Na is set to 58.3.

The pile tip area Ap is calculated from Ap = π · (Don / 2) ² .

  The pile peripheral surface friction force coefficient β in the sandy / gravel ground is β = 5 to 8 in the straight portion of the pile. In addition, β = 9.5ω and β · Ns = (30 + 5.5Ns) · ω are satisfied in the node portion of the pile.

  Of the ground around the pile, the average value Ns of the sandy ground is 1 or more, and when Ns> 30, Ns is 30. On the other hand, of the ground around the pile, the total length Ls in contact with the sandy / gravel ground is calculated excluding the distance from the tip of the pile to a position of 2 m.

The pile peripheral surface friction force coefficient γ in the clayey ground is β = 0.7 to 9.0 in the straight portion of the pile. Further, a value satisfying γ = 1.0ω and _{γ · q u = (20 +} 0.5q u) · ω in the section portion of the pile.

Of the ground around the pile, the average value q _u of the uniaxial compressive strength of the clay-based ground is 10 kN / m ² or more, and when q _u > 200 kN / m ² , q _u is 200 kN / m ² . Of the ground around the pile, the total length Lc in contact with the clay-based ground is calculated by excluding the distance from the tip of the pile to a position of 2 m.

  The pile circumference Φ is calculated as Φ = π · D. Here, D is a pile diameter (m). In the case of joint piles, the diameter is the node diameter.

  In Formula (3), the safety factor μ, the pile tip supporting force coefficient α, the pile peripheral surface friction force coefficients β, γ, and the like are appropriately set according to the field conditions such as geology.

  After the process S11 is completed, next, various data relating to the ready-made pile 10 are examined and adjusted to determine the calculated value of the expansion ratio ω of the expanded excavation part 5 (process S12). In this process S12, as various data concerning the ready-made pile 10 to be examined, the pile length L, the pile diameter D (node diameter Don in this embodiment), the PHC pile, and the RC pile are specifically constructed. , PRC piles, steel piles, SC piles, node piles, and other types of piles, enlargement ratio ω of the enlarged excavation part 5 for forming the tip consolidation part 14, and an enlarged excavation part length Lω. As shown in Equation (1) described above, in this embodiment, the expansion ratio ω is relative to the outer diameter design value Ds obtained by adding the desired clearance value x to the outer diameter Don of the tip portion 10a of the ready-made pile 10. The ratio of the internal diameter De of the expansion excavation part 5 is shown.

  Generally, when the pile length L is increased, the pile diameter D is increased, the enlargement ratio ω is increased, and the expanded excavation portion length Lω is increased, the support force of the ready-made pile 10 is increased. When the supporting force of the ready-made pile 10 is increased, it is necessary to increase the material strength by increasing the concrete strength of the ready-made pile 10 or increasing the plate thickness of the steel pipe. Also, construction equipment such as a hydraulic expansion device is required during construction. For this reason, the specifications of construction equipment increase and the cost increases.

  In addition, although this embodiment demonstrated the case where process S12 was implemented after process S11, you may implement process S11 and process S12 simultaneously. That is, the pile length L, the pile diameter D, the pile type, the enlargement ratio ω, and the enlarged excavation length Lω may be set at the same time as the number of piles J and the calculated design support force R of the piles are set.

  A design value expansion ratio ωd and an expanded excavation length Lωd, which are optimum values obtained based on various data relating to the ready-made pile 10 adjusted in step S12, are set (setting step S13). After that, enlargement ratio ωc (ωc <ωd) that prioritizes cost by reducing the enlargement ratio relative to the design value enlargement ratio ωd, and enlargement that emphasizes safety by increasing the enlargement ratio relative to the design value enlargement ratio ωd The ratio ωs (ωs> ωd) is set (setting step S14). In the present embodiment, in step S14, the expanded excavation section length Lωc (Lωc <Lωd) in which the expanded excavation section length is shortened and the cost is prioritized with respect to the expanded excavation section length Lωd and the expanded excavation section length Lωd is expanded. The extended excavation section length Lωs (Lωs> Lωd) that places importance on safety is set.

In addition, the design value expansion ratio ωd and the expanded excavation section length Lωd of the expanded excavation section 5 are set based on data based on the ground columnar diagram created by the ground survey, construction results, past accumulated data, and the like. Further, in the present embodiment, the enlargement ratio ωc giving priority to cost is calculated as a lower enlargement ratio obtained by subtracting a predetermined value from the design value enlargement ratio ωd, and the enlargement ratio ωs emphasizing safety is the design value enlargement ratio. It is calculated as an upper magnification ratio obtained by adding a predetermined value to ωd. Specifically, the enlargement ratio ωc and the enlargement ratio ωs are set by calculating from the following equations (8) and (9), respectively.
ωc = ωd−σ (8)
ωs = ωd + σ (9)

  Here, σ added and subtracted as a predetermined value in Expressions (8) and (9) is a deviation, for example, 0.1 to 0.3. The said deviation is set based on the data by the ground columnar figure created by the ground survey, construction results, past accumulated data, and the like.

  In the present embodiment, in the setting steps S <b> 13 and S <b> 14, a plurality of enlargement ratios ω of the enlarged excavation part 5 are set with different values based on predetermined data relating to the construction of the ready-made pile 10. Specifically, the design value expansion ratio ωd set to an optimum value based on at least predetermined data, the cost priority expansion ratio ωc obtained by subtracting a predetermined value from the design value expansion ratio ωd, and the value reduced, and the design A safety priority expansion ratio ωs is set by adding a predetermined value to the value expansion ratio ωd and increasing the value. Further, for each case of the expansion ratios ωd, ωc, and ωs, the expanded excavation section lengths Lωd, Lωc, and Lωs are set, respectively.

  In the present embodiment, the enlargement ratio ω and the enlarged excavation part Lω are each set in three ways. However, in order to examine the validity of the design values of the enlargement ratio ω and the enlarged excavation part length Lω, at least two kinds are set. It is sufficient if the above is set, and when the validity of the design value is further examined, four or more patterns may be provided. In this embodiment, the expansion ratio ω and the expanded excavation length Lω are each set in three ways. However, since it is necessary to examine at least the validity of the expansion ratio ω, only a plurality of expansion ratios ω are provided. It may be.

  As described above, in the present embodiment, in the setting steps S13 and S14, the design value magnification ratio ωd, the magnification ratio ωc smaller than the design value magnification ratio ωd, and the magnification ratio ωs larger than the design value magnification ratio ωd are set. ing. For this reason, even when there is a difference between the design value expansion ratio ωd calculated in advance and the expansion ratio ω determined based on the actual measurement value measured in the loading test performed at the construction site, the design value expansion The final optimum enlargement ratio ωopt can be determined after further examining the validity of the ratio ωd. In addition, by obtaining the expanded excavation lengths Lωd, Lωc, and Lωs corresponding to the respective cases of the respective expansion ratios ωd, ωc, and ωs, the validity of the design values including the expanded excavation length Lω is scrutinized and finally The size of the enlarged excavation part 5 can be ensured.

  When the setting steps S13 and S14 are finished, the test pile 10 'is then constructed (test pile construction step S15). The construction of the test pile 10 ′ is performed on the ground GN at the construction site where the ready-made pile 10 is actually built. In the test pile construction process S15, there are cases where the test piles 10 'corresponding to the respective enlargement ratios ωd, ωc, and ωs are all enforced and separately as necessary. Details of the test pile construction step S15 will be described later.

  Next, a loading test is performed for each of the cases having one or more enlargement ratios selected from the plurality of enlargement ratios ωd, ωc, and ωs, and the design support of the ready-made pile 10 at the one or more enlargement ratios ω is performed. Each of the forces R is measured (design support force measurement step S16). In this embodiment, in order to closely examine the validity of the design value, the enlargement ratio ω and the enlarged excavation part Lω are set in three ways, respectively. The cost is also heavy. For this reason, in the construction method of the ready-made pile 10 which concerns on this embodiment, in order to suppress the loading test in the construction site which actually builds the ready-made pile 10 in the pile hole 3 by the required minimum frequency, the procedure which implements a loading test It is ingenuity. The details of the design support force measurement step S16 will be described later.

When the design support force measurement step S16 is completed, the design support force R is measured for each Rωi (Rωi is at least one of Rωd, Rωc, and Rωs) measured in the design support force measurement step S16. The product of the supporting force Rωi and the number of ready-made piles 10 to be used is obtained. Then, it is determined whether or not the product is greater than or equal to a desired design load (column load) P acting on the pile foundation 1 formed by the ready-made pile 10 (design support force determination step S17). In the present embodiment, it is determined whether or not the design support force Rωi satisfies the following conditional expression (10) for the case of the enlargement ratio ω for which the loading test has been performed.
Number of piles J x design bearing force Rωi ≥ margin M x design load (column load) P ... (10)

  Next, in the design support force determination step S17, the product of the design support force Rωi and the number of ready-made piles 10 used is equal to or greater than the desired design load (column load) P, that is, the margin M and the design load (column load). Among the expansion ratios ωd, ωc, and ωs that satisfy the condition that is not less than the product of P, the minimum expansion ratio ωi is determined as the optimal expansion ratio ωopt for forming the expanded excavation portion 5 (optimal expansion ratio determination step S18). . In the present embodiment, in the optimum enlargement ratio determination step S18, optimum values ωopt and Lωopt of the enlarged excavation section length Lω corresponding to the enlargement ratio ω and the enlargement ratio ω are determined. Then, in the process of excavating the pile hole 3, the enlarged excavation part 5 is formed based on the optimum enlargement ratio ωopt and the optimum enlarged excavation part length Lωopt (enlarged excavation part forming step S19). After that, various processes for building and constructing the ready-made pile 10 in the excavated pile hole 3 are performed.

  Thus, in the construction method of this embodiment, it is formed on the bottom side of the pile hole 3 with as few loading tests as possible while reflecting the test data of the loading test conducted at the construction site where the ready-made pile 10 is actually built. It is possible to set the optimum expansion ratio ωopt of the expanded excavation section 5 to be performed. For this reason, while reducing the labor and cost of the loading test, the optimum enlargement ratio ωopt is determined by reflecting the measurement results at the actual construction site, so the overspec when forming the enlarged excavation part 5 is reliably reduced. can do. Moreover, in the construction method of this embodiment, since the high stop of the ready-made pile 10 can be prevented reliably, it can construct reliably in a design depth position. Furthermore, the pile support capacity can be set according to the type of pile, pile diameter, pile length, expansion ratio of the tip consolidation part, enlarged excavation part length of the tip consolidation part, etc. according to the ground strength. The optimal and economical design and construction can be performed.

  In addition, in setting process S14, it can also set by the method (A) thru | or (C) described below as a method of setting expansion ratio (omega) c and (omega) s based on the predetermined data etc. which concern on construction of a ready-made pile. .

(Setting by method (A))
Based on the ultimate bearing capacity of the pile, the following procedure is used. This procedure will be described with reference to Table 1 below.

First, as shown in Table 1, the design value expansion ratio ωd (ωd = 1.3 in Table 1), the expanded excavation section length Lωd, as shown in Table 1, by the cost comparison of the pile setting as described above based on the geological conditions, load conditions, etc. (Lωd = 10 m), safety factor μ _d (μ _d = 2.5) and design support force Rωd (calculated value) (Rωd = 3600 kN) are set. At this time, the safety factor μ is set based on the magnification with respect to the design support force to be confirmed in the loading test, past performance data, and the like. In the case of Table 1, it is assumed that 2.5 times the design support force is confirmed in the loading test.

Next, the set design support force Rωd (calculated value) and the safety factor μ _d (= 2.5) are substituted into the following equation (11) to calculate the ultimate support force Ru _d (Ru _d = 9000 kN). To do.
Ru _d = Rωd (calculated value) × μ _d (11)

Next, safety factors μ _c and μ _s (μ _c = 2 and μ _s = 3) corresponding to the cases of the enlargement ratios ωc and ωs are set. Note that the safety factors μ _c = 2 and μ _s = 3 are applied only when setting the enlargement ratios ωc and ωs, and other specifications of the pile, such as the design bearing force R (calculated value), etc. It does not apply when setting. That is, other specifications of the pile are calculated with a safety factor μ = 2.5.

Subsequently, the design support force Rωd (calculated value) and the safety factors μ _c and μ _s calculated above are substituted into the following expressions (12) and (13), respectively, and the ultimate support forces Ru _c and Ru are obtained. _{s (Ru c = 7200kN, Ru} s = 10800kN) is calculated.
Ru _c = Rωd (calculated value) × μ _c (12)
Ru _s = Rωd (calculated value) × μ _s (13)

The pile of specifications (pile diameter, pile length, etc.) without changing the expansion ratio .omega.c satisfying ultimate bearing capacity _{Ru c (Ru c = 7200kN)} (ωc = 1.1) and enlargement Division Lωc (Lωc = 8m ) Is calculated.

Further, similarly to the ultimate support force Ru _c , the enlargement ratio ωs (ωs = 1.5) and the enlarged excavation section length Lωs (Lωs = 9 m) satisfying the ultimate support force Ru _s (R _s = 10800 kN) are calculated.

(Setting by method (B))
It is set based on the relationship between the design support force R (calculated value) of the pile calculated from the above-described equation (3) and the design support force R of the pile measured by the loading test. In addition, the design support force R of the pile measured by the loading test is hereinafter referred to as the design support force R (measured value).

  FIG. 4 is a diagram showing the relationship between the design support force R (calculated value) and the design support force R (measured value) of the pile. 4 is a straight line when the design support force R (calculated value) and the design support force R (measured value) have a one-to-one relationship (in the legend in the figure, Rac = Rat). It is.

  As shown in FIG. 4, the design support force R (measured value) of the pile is larger than the design support force R (calculated value). A correlation is confirmed between the design support force R (measured value) and the design support force R (calculated value). In the present embodiment, an average value (a dotted line in FIG. 4) of a ratio (measured value / calculated value) of each design support force R (measured value) to a plurality of design support forces R (calculated values) is, for example, about 1. It has doubled.

  The cost-oriented enlargement ratio ωc is examined and set from the average value or the average value −1.06σ. For example, when the average value of 1.2 is adopted, when the calculated value of the ultimate support force based on the design value enlargement ratio ωd is 6000 kN, the ultimate support force becomes 5000 kN by dividing 6000 kN by the value 1.2. Set the ratio ωc.

  Further, the enlargement ratio ωs is set from the same value or the lowest value depending on the actual performance that is less than the design support force R (measured value). For example, the ratio (measured value / calculated value) of the data of the design support force R (measured value) below the design support force R (calculated value) to the design support force R (calculated value) is 0.95. If the calculated value of the ultimate bearing force Rud based on the design value magnification ratio ωd is 6000 kN, for example, by dividing the calculated value 6000 kN of the ultimate bearing force Rud by 0.95, An enlargement ratio ωs is set to 6320 kN.

(Setting by method (c))
Set based on past tip support force data using a ground column diagram or the like. That is, when the tip bearing capacity of a pile can be evaluated based on the data of the past loading test, it sets based on the data.

  Next, the detail of the construction method of the foundation pile by the foundation pile construction system of this embodiment is demonstrated, using drawing. FIG. 5 is a flowchart showing details of a foundation pile construction method according to an embodiment of the present invention. In FIG. 5, in particular, after passing through the setting steps S13 and S14 of the enlargement ratio ω, setting up the test pile, measuring the design support force, determining the appropriateness of the design support force, and determining the optimum enlargement ratio A simple flow will be described.

  As shown in FIG. 5, first, test pile 10 'is constructed in the vicinity of the ground GN of the construction site where the ready-made pile 10 is actually built (test pile construction process S15). In the present embodiment, all the test piles 10 'corresponding to the respective enlargement ratios ωd, ωc, and ωs are executed.

  Next, among the test piles 10 ′ corresponding to the respective expansion ratios ωd, ωc, and ωs, the test piles corresponding to the design value expansion ratio ωd that is the optimum value obtained in advance based on various data related to the ready-made pile 10. A 10 'loading test is carried out (step S16-1). That is, in this embodiment, in order to give the highest priority to the validity of the design value enlargement ratio ωd, a loading test is performed from the case of the design value enlargement ratio ωd, and the design support force corresponding to the design value enlargement ratio ωd Rωd is measured.

  After measuring the design support force Rωd, the process proceeds to the design support force determination step S17-1, and the product of the design support force Rωd measured based on the design value enlargement ratio ωd and the number J of ready-made piles 10 is It is determined whether or not the desired design load (column load) P acting on the pile foundation 1 formed by the ready-made pile 10 and the margin M are greater than or equal to each other. That is, it is examined whether or not the conditional expression (10) described above is satisfied.

If the product of the design support force Rωd and the number J of ready-made piles 10 is greater than or equal to the product of the margin M and the design load (column load) P in the design support force determination step S17-1, then the design support force The predicted design support force Rωc ′ is estimated based on the design support force Rωd measured in the measurement step S16-1 (predicted design support force estimation step S17-1a). The predicted design bearing force Rωc ′ was measured by the ultimate bearing force Ru _d (calculated value) and Ru _c (calculated value) calculated for each case of the set design value magnification ratio ωd and magnification ratio ωc, respectively, and a load test. It is estimated from the ratio with the ultimate support force Ru _d (measured value) calculated based on the design support force Rωd (measured value).

Specifically, it estimates using the formula (14) shown below.
Rωc ′ = Ru _d (measured value) / (Ru _d (calculated value) / Ru _c (calculated value)) (14)

When the influence of the enlargement ratio ω is 2/3 of the ultimate support force, it is estimated using the following formula (15).
Rωc' = {Ru _d (measured value) -Ru _d (calc)} × 2/3 + Ru c ( calc) (15)

  In this way, it is possible to reliably set a more suitable optimum enlargement ratio ωopt after further examining the validity of the design value enlargement ratio ωd set in the setting step S13.

  A method for estimating the predicted design support force Rωc ′ from the above-described formula (14) or formula (15) will be specifically described with reference to Table 1 and Table 2 below.

As shown in Table 1, the safety factor μd in the case of the enlargement ratio ωd = 1.3 is set to 2.5, and the safety factor μc in the case of the enlargement ratio ωc = 1.1 is set to 2. Subsequently, the respective enlargement ratios ωd and ωc and the safety factors μd and μc are substituted into the above-described equations (11) and (12), respectively, and the ultimate bearing forces Ru _d (calculated values) and Ru _c (calculated values) are obtained. calculate. (Specifically, the ultimate bearing force Ru _d (calculated value) = 9000 kN, the ultimate bearing force Ru _c (calculated value) = 7200 kN)

Next, as shown in Table 2, the ultimate support force Ru _d (measured value) = 11500 kN is calculated based on the design support force R (measured value) measured by the loading test. Then, the predicted design support force Rωc ′ is calculated by substituting the calculated ultimate support force Ru _d (calculated value), Ru _c (calculated value) and the ultimate support force Ru _d (measured value) into the above-described equation (14). To do. In this manner, the predicted design support force Rωc ′ is estimated and obtained based on the design support force Rωd measured in the design support force measurement step S16-1.

  That is, in the predicted design support force estimation step S17-1a, the design support force Rωd (calculated value) is compared with the actual design support force Rωd (measured value) to correct the design support force Rωd (calculated value). The difference which shows the shift | offset | difference degree with the said calculated value used as a candidate is grasped. Then, the predicted design support force Rωc ′ is estimated by correcting the design support force Rωc (calculated value) by the difference. In other words, in the predicted design support force estimation step S17-1a, at least the design support force Rωd (actual value) measured in the design support force measurement step S16 and the design value expansion ratio ωd set in the setting step S13 are calculated. A difference from the design support force Rωd (calculated value) is calculated, and the predicted design support force is corrected by correcting the magnitude of the difference with respect to the design support force Rωc calculated for the cost priority enlargement ratio ωc that is the lower enlargement ratio. Rωc ′ is estimated.

  As shown in FIG. 5, after estimating the predicted design support force Rωc ′, it is examined whether or not the condition that the predicted design support force Rωc ′ is greater than the design support force Rωd (calculated value) is satisfied (predicted design support). Force determination step S17-1b). That is, in the predicted design support force determination step S17-1b, the predicted design support force Rωc ′ calculated in the predicted design support force estimation step S17-1a is based on the design value expansion ratio ωd in the design support force measurement step S16. It is determined whether or not the measured design support force Rωd (actual value) is greater.

  If the predicted design support force Rωc ′ is greater than the design support force Rωd (actual measurement value) in the predicted design support force determination step 17-1b, then a loading test is performed on the case with the cost priority expansion ratio ωc (step S16). -2). In this loading test, the design support force Rωc (measured value) corresponding to the cost priority enlargement ratio ωc is measured.

  Next, it is determined whether or not the product of the number of piles J and the design support force Rωc (measured value) is equal to or greater than the product of the margin M and the design load (column load) P (step S17-2). When the product of the number of piles J and the design support force Rωc (measured value) satisfies the condition equal to or greater than the product of the margin M and the design load (column load) P in step S17-2, the cost-enhanced expansion ratio ωc Is determined as the optimum enlargement ratio ωopt (step S18-1). In step S18-1, the optimum enlargement ratio ωopt is determined, and at the same time, the enlarged excavation part length Lωc determined in step S14 corresponding to the enlargement ratio ωc is decided as the optimum enlargement part length Lωopt.

  Then, it transfers to process S19 and implements this pile construction based on the case of the optimal expansion ratio omegaopt determined by process S18-1, and the optimal expansion excavation part length Lomegaopt. Thereby, construction cost can be reduced rather than implementing this pile construction based on the case of design value expansion ratio omegad.

  On the other hand, if the product of the number of piles J and the design support force Rωc (measured value) is smaller than the product of the margin M and the design load (column load) P as a result of the examination in step S17-2, the design value The enlargement ratio ωd is determined as the optimum enlargement ratio ωopt, and the enlarged excavation part length Lωd corresponding to the design value enlargement ratio ωd is determined as the optimum enlargement part length Lωopt (step 18-2). And it transfers to process S19 and implements this pile construction based on the case of optimal expansion ratio omegaopt and optimal expansion excavation part length Lomegaopt.

  When the predicted design support force Rωc ′ is smaller than the design support force Rωd (calculated value) as a result of the examination in the predicted design support force determination step S17-1b, the design value enlargement ratio ωd is determined as the optimum enlargement ratio ωopt. Then, the expanded excavation section length Lωd corresponding to the design value expansion ratio ωd is determined as the optimum expanded section length Lωopt (step 18-2). And it transfers to process S19 and implements this pile construction based on the case of optimal expansion ratio omegaopt and optimal expansion excavation part length Lomegaopt.

  Therefore, in this case, it is not necessary to perform the loading test for the case of the cost-priority expansion ratio ωc. Since the loading test requires a lot of time and cost, it is preferable to perform the loading test as few times as possible. For this reason, it is desirable to avoid performing the loading test in step S16-2 when the process proceeds from the predicted design supporting force determination step S17-1b to step S18-2. Specifically, in spite of having performed step S16-2, in step S17-2, the product of the number of piles J and the design support force Rωc (measured value) is the product of the margin M and the design load (column load) P. In the end, it is desirable to avoid the formation of an enlarged excavation part with the design value enlargement ratio ωd in Steps S18-2 and S19, that is, the waste of the loading test at the enlargement ratio ωc.

  As described above, in the present embodiment, by estimating the predicted design support force Rωc ′, in step S17-2, the product of the number of piles J and the design support force Rωc (measured value) becomes the margin M and the design load (column The probability that it is equal to or higher than the product of the load (P) can be remarkably improved. As a result, it is possible to omit a loading test for a case with a wasteful enlargement ratio ωc, so that it is possible to shorten the construction period and further reduce the cost.

  In addition to this, in the present embodiment, in order to form the enlarged excavation portion 5 that does not become over-spec based on the calculated value of the design support force R based on the enlargement ratio ω and the measurement result of the actual measurement value, the enlargement ratio ω Are set as the set value expansion ratio ωd, the cost priority expansion ratio ωc, and the safety priority expansion ratio ωs. Then, based on the actual loading test result, a more suitable optimum enlargement ratio ωopt is set. In such a case, a suitable optimum enlargement ratio ωopt is determined after further examination of the appropriateness of the design value enlargement ratio ωd, which is the median value of the enlargement ratio ω. Therefore, the construction site where the ready-made pile 10 is actually built in the pile hole 3 While the loading test carried out in (1) is completed with the minimum number of times necessary, it is possible to set a suitable optimum enlargement ratio ωopt that reliably reflects the test data of the loading test.

  On the other hand, if it is determined in step S17-1 that the product of the design support force Rωd (measured value) and the number J of ready-made piles 10 is smaller than the product of the margin M and the design load (column load) P, A loading test is performed on the case with the priority enlargement ratio ωs, and the design support force Rωs of the ready-made pile 10 is measured (step S16-3). Thereafter, it is examined whether or not the product of the number of piles J and the design support force Rωs (measured value) is greater than or equal to the product of the margin M and the design load (column load) P. That is, in the case of the design support force Rωs (measured value), it is examined whether or not the conditional expression (2) described above is satisfied (step S17-3).

  In step S17-3, when the product of the number of piles J and the design support force Rωs (measured value) is equal to or greater than the product of the margin M and the design load (column load) P, the safety priority priority enlargement ratio ωs is optimized. The enlargement ratio ωopt is determined (step S18-3). In step S18-3, the optimum enlargement ratio ωopt is determined, and at the same time, the enlarged excavation portion length Lωs determined in step S14 corresponding to the enlargement ratio ωs is decided as the optimum enlargement portion length Lωopt. Then, it transfers to process S19 and implements this pile construction based on the case of the optimal expansion ratio omegaopt determined by process S18-3, and the optimal expansion excavation part length Lomegaopt.

  On the other hand, if it is determined in step S17-3 that the product of the number of piles J and the design support force Rωs (measured value) is smaller than the product of the margin M and the design load (column load) P, a new design A support force R is set, and a new pile number J is calculated (step S17-3a). For example, with the setting of a new design support force R, the number of piles is increased by one as a new pile number J (= J + 1). The cost is compared among the design value enlargement ratio ωd and the enlargement ratio ωs to determine the cheaper one as the optimum enlargement ratio ωopt, and at the same time, the enlarged excavation section length Lωd determined in step S14 corresponding to the enlargement ratio ωopt, Any one of Lωs is determined as the optimum enlarged portion length Lωopt (step 18-4). Then, it transfers to process S19 and implements this pile construction based on the case of the optimal expansion ratio omegaopt determined by process S18-4, and the optimal expansion excavation part length Lomegaopt.

  As described above, according to the present embodiment, the validity of the design value magnification ratio ωd, which is the median value of the magnification ratios ω set in a plurality of ways, is further examined in accordance with the flow described above, and then performed at the actual construction site. A suitable optimum enlargement ratio ωopt based on the loading test result is determined. For this reason, it is possible to set a suitable optimal enlargement ratio ωopt based on actual loading test data more reliably while completing the loading test with the necessary minimum number of times. Over-spec at the time of forming can be reduced. Moreover, since the high stop of the ready-made pile 10 can be prevented reliably, it can construct reliably in a design depth position. Furthermore, in this embodiment, since the number of times of performing the loading test can be surely kept within two times, it is easy to assemble a work process in the process of constructing the ready-made pile 10.

  In this embodiment, in the test pile construction step S15, all the test piles 10 'corresponding to the respective enlargement ratios ωd, ωc, and ωs are performed, but may be performed separately as necessary. If it does in this way, construction of test pile 10 'can also be completed by minimum necessary. FIG. 6 is a flowchart showing details of a modification of the foundation pile construction method according to one embodiment of the present invention.

  As shown in FIG. 6, in the modification of the present embodiment, first, in the vicinity of the ground GN in which the ready-made pile 10 is actually built, the test pile 10 ′ corresponding to the ready-made pile 10 in the case of the design value expansion ratio ωd. Is implemented (test pile construction process S15-1). Next, a loading test of the test pile 10 ′ corresponding to the design value expansion ratio ωd is performed (step S16-1), and the design support force Rωd is measured.

  When the design support force Rωd is measured in the loading test in step S16-1, the design support force determination step S17-1 to the predicted design support force determination step S17-1b are performed as described above.

  When the predicted design support force Rωc ′ is larger than the design support force Rωd (calculated value) in the predicted design support force determination step 17-1b, next, the test pile 10 ′ is tested in the case of the cost priority expansion ratio ωc. Construction is performed (step S15-2).

  Then, as described above, steps S16-2 to S18-1 are performed. Then, it transfers to process S19 and implements this pile construction based on the case of the optimal expansion ratio omegaopt determined by process S18-1, and the optimal expansion excavation part length Lomegaopt.

  On the other hand, when the predicted design support force Rωc ′ is equal to or less than the design support force Rωd (calculated value) in the predicted design support force determination step S17-1b, step 18-2 is performed as described above. Then, it transfers to process S19 and implements this pile construction.

  If it is determined in step S17-1 that the product of the design support force Rωd and the number J of ready-made piles 10 is smaller than the product of the margin M and the design load (column load) P, then the design support force is continued. A predicted design support force Rωs ′ is estimated based on the design support force Rωd measured in the measurement step S16-1 (predicted design support force estimation step S17-1c). Note that the method for estimating the predicted design support force Rωs ′ in the predicted design support force estimation step S17-1c is the same as described above, and thus the description thereof is omitted.

  Thereafter, test construction is performed for the case of the expansion ratio ωs giving priority to safety (step S15-3). Then, as described above, Steps S16-3 to S18-3 or Step 18-4 are performed. Then, it transfers to process S19 and implements this pile construction based on the case of the optimal expansion ratio omegaopt determined by process S18-3 or process 18-4, and the optimal expansion excavation part length Lomegaopt.

  As described above, in the modification of the present embodiment, the construction of the test pile 10 ′ corresponding to each of the expansion ratios ωd, ωc, and ωs is not performed from the beginning, and the necessary minimum value including the design value expansion ratio ωd is included. Only the test construction is performed, and the loading test of the test pile 10 ′ corresponding to the enlargement ratio ω subjected to the test construction is performed. For this reason, it is not necessary to excavate the test hole 3 'more than necessary, and wasteful excavation work can be reduced.

  Further, in the modified example of the present embodiment, the validity of the design value magnification ratio ωd, which becomes the median value of the magnification ratio ω set in a plurality of ways, is further examined according to the flow described above, and then the result of the actual loading test is performed. A suitable optimal enlargement ratio ωopt is determined. For this reason, it is possible to set a suitable optimum enlargement ratio ωopt that reflects the data of the actual loading test more reliably while completing the loading test with the necessary minimum number of times.

(Second Embodiment)
Next, the detail of the construction method of the foundation pile which concerns on the 2nd Embodiment of this invention is demonstrated, using drawing. FIG. 7 is a flow chart showing details of a foundation pile construction method according to another embodiment of the present invention. In FIG. 7, in particular, after setting steps S13 and S14 for the enlargement ratio ω, setting of the test pile, measurement of the design support force R, determination of the validity of the design support force R, and determination of the optimum enlargement ratio ωopt are performed. A detailed flow up to this point will be described.

  As shown in FIG. 7, in this embodiment, in order to set the optimum enlargement ratio ωopt that does not become over-specification more efficiently and reliably, the design support force in order from the smallest of the plurality of enlargement ratios ωd, ωc, and ωs. R is determined. That is, the loading test is performed from the test pile 10 'corresponding to the cost-prioritized expansion ratio ωc among the expansion ratios ωd, ωc, and ωs set in the setting steps S13 and S14 (see FIG. 3).

  First, in the vicinity of the ground GN in which the ready-made pile 10 is actually built, the test pile 10 ′ corresponding to the ready-made pile 10 is installed (test pile construction step S25). In the present embodiment, all the test piles 10 'corresponding to the respective enlargement ratios ωd, ωc, and ωs are executed.

  Next, among the test piles 10 ′ corresponding to the respective expansion ratios ωd, ωc, and ωs, a loading test of the test pile 10 ′ corresponding to the cost priority expansion ratio ωc is performed (step S26-1). In other words, in the present embodiment, in order to give the highest priority to the validity of the cost-priority expansion ratio ωc having a small value, a loading test is performed from the case of the expansion ratio ωc, and the design support corresponding to the expansion ratio ωc is supported. Measure force Rωc.

  When the design support force Rωc is measured, the process proceeds to the design support force determination step S27-1, and the design support force Rωc (hereinafter referred to as the design support force Rωc (measured value)) measured based on the design value enlargement ratio ωc. ) And the number J of ready-made piles 10 is determined as to whether or not the product of the margin M and the design load (column load) P is equal to or greater.

  In the design support force determination step S27-1, when the product of the design support force Rωc (measured value) and the number J of ready-made piles 10 is equal to or greater than the product of the margin M and the design load (column load) P, The expansion ratio ωc giving priority to the cost is determined as the optimal expansion ratio ωopt, and at the same time, the expanded excavation section length Lωc determined in step S14 corresponding to the expansion ratio ωc is determined as the optimal expansion section length Lωopt (step S28-1).

  And it transfers to process S19 and implements this pile construction based on the case of the optimal expansion ratio omegaopt determined by process S28-1, and the optimal expansion excavation part length Lomegaopt. Thereby, construction cost can be reduced rather than implementing this pile construction based on the case of expansion ratio ωd.

  On the other hand, in Step S27-1, when it is determined that the product of the design support force Rωc (measured value) and the number J of ready-made piles 10 is smaller than the product of the margin M and the design load (column load) P, A loading test is performed on the case with the design value expansion ratio ωd, and the design support force Rωd of the ready-made pile 10 is measured (step S26-2).

  Thereafter, it is examined whether or not the product of the number of piles J and the design support force Rωd (measured value) is greater than or equal to the product of the margin M and the design load (column load) P (step S27-2). That is, in the case of the design support force Rωd, it is examined whether or not the conditional expression (2) described above is satisfied.

  In step S27-2, when the product of the number of piles J and the design support force Rωd (measured value) is equal to or greater than the product of the margin M and the design load (column load) P, the design value enlargement ratio ωd is optimized. The expansion ratio ωopt is determined, and at the same time, the expanded excavation portion length Lωd determined in step S14 corresponding to the expansion ratio ωd is determined as the optimal expansion portion length Lωopt (step S28-2). In step S28-2, when the enlargement ratio ωd is determined to be the optimum enlargement value ωopt, the process proceeds to step S19, and based on the case of the optimum enlargement ratio ωopt and the optimum enlarged excavation section length Lωopt determined in step S28-2. Implement this pile construction.

  On the other hand, when it is determined in step S27-2 that the product of the design support force Rωd (measured value) and the number of ready-made piles 10 is smaller than the product of the margin M and the design load (column load) P, A loading test is performed on the case of the safety expansion ratio ωs, and the design support force Rωs of the ready-made pile 10 is measured (step S26-3).

  Thereafter, it is examined whether or not the product of the number of piles J and the design support force Rωs (measured value) is greater than or equal to the product of the margin M and the design load (column load) P (step S27-3). That is, in the case of the design support force Rωs (measured value), it is examined whether or not the conditional expression (2) described above is satisfied.

  In step S27-3, when the product of the number of piles J and the design support force Rωs (measured value) is equal to or greater than the product of the margin M and the design load (column load) P, the enlargement ratio ωs is set to the optimum enlargement ratio. At the same time, the expanded excavation section length Lωs determined in step S14 corresponding to the expansion ratio ωs is determined as the optimal expansion section length Lωopt (step S28-3). In step S28-3, when the enlargement ratio ωs is determined to be the optimum enlargement value ωopt, the process proceeds to step S19. Based on the case of the optimum enlargement ratio ωopt and the optimum enlarged excavation section length Lωopt determined in step S28-3. Implement this pile construction.

  On the other hand, when the product of the pile number J and the design support force Rωs (measured value) is smaller than the product of the margin M and the design load (column load) P in step S27-3, a new design support force R is obtained. And a new pile number J is calculated (step S27-3a). For example, with the setting of the new design support force R, the new pile number J is set to (J + 1), and the pile number is increased by one. Then, the cost is compared among the enlargement ratios ωd and ωs, and the cheaper one is determined as the optimum enlargement ratio ωopt, and at the same time, one of the enlarged excavation section lengths Lωd and Lωs determined in step S14 corresponding to the enlargement ratio ωopt. Is determined as the optimum enlarged portion length Lωopt (step S28-4). Then, it transfers to process S19 and implements this pile construction based on the case of the optimal expansion ratio omegaopt determined by process S28-4 and the optimal expansion excavation part length Lomegaopt.

  Thus, in this embodiment, since the loading test is carried out from the test pile 10 ′ corresponding to the cost-priority expansion ratio ωc at the construction site where the ready-made pile 10 is actually built, the loading test result at the actual construction site The optimal enlargement ratio ω based on For this reason, it is possible to set the optimum value ωopt of the enlargement ratio ω that does not become over-specification more efficiently based on the ground strength at the actual construction site.

  Further, since the loading test is performed from the test pile 10 ′ corresponding to the cost-prioritized enlargement ratio ωc, when the optimum enlargement ratio ωopt is set to a smaller value of the enlargement ratio ω, it corresponds to the enlargement ratio ω. It is possible to minimize the number of times the loading test of the design support force R is performed. In other words, when the cost priority enlargement ratio ωc is determined to be the optimum enlargement ratio ωopt, the load test can be performed only once, so the optimum value ωopt of the enlargement ratio ω that does not become over-specification is set more efficiently. can do.

  In this embodiment, in the test pile construction step S25, all the test piles 10 'corresponding to the respective enlargement ratios ωd, ωc, and ωs are performed, but may be performed separately as necessary. If it does in this way, construction of test pile 10 'can also be completed by minimum necessary. FIG. 8: is a flowchart which shows the detail of the modification of the construction method of the foundation pile which concerns on other embodiment of this invention.

  As shown in FIG. 8, in the modification of the present embodiment, in order to more efficiently and surely set the optimum expansion ratio ωopt that does not become overspec, first, in the vicinity of the ground GN that actually builds the ready-made pile 10, About the case of expansion ratio (omega) c, construction of test pile 10 'corresponding to the ready-made pile 10 is implemented (test pile construction process S25-1).

  Next, as described above, step S26-1 is performed, and then step S28-1 is performed through step S27-1.

  And it transfers to process S19 and implements this pile construction based on the case of the optimal expansion ratio omegaopt determined by process S28-1, and the optimal expansion excavation part length Lomegaopt. Thereby, construction cost can be reduced rather than implementing this pile construction based on the case of expansion ratio ωd.

  On the other hand, if it is determined in step S27-1 that the product of the design support force Rωc (measured value) and the number J of ready-made piles 10 is smaller than the product of the margin M and the design load (column load) P, A predicted design support force Rωd ′ is estimated based on the design support force Rωc (measured value) measured in S27-1 (predicted design support force estimation step S27-1a). Note that the method for estimating the predicted design support force Rωd ′ in the predicted design support force estimation step S27-1a is the same as described above, and a description thereof will be omitted.

  Then, about the case of design value expansion ratio omegad, construction of test pile 10 'corresponding to ready-made pile 10 is carried out (test pile construction process S25-2).

  Next, as described above, step S26-2 is performed, and then step S28-2 is performed through step S27-2. And it transfers to process S19 and implements this pile construction based on the case of the optimal expansion ratio omegaopt determined by process S28-2, and the optimal expansion excavation part length Lomegaopt.

  On the other hand, when it is determined in step S27-2 that the product of the design support force Rωd (measured value) and the number J of ready-made piles 10 is smaller than the product of the margin M and the design load (column load) P, A predicted design support force Rωs ′ is estimated based on the design support force Rωd (measured value) measured in step S26-2 (predicted design support force estimation step S27-2a). Note that the method for estimating the predicted design support force Rωs ′ in the predicted design support force estimation step S27-2a is the same as described above, and a description thereof will be omitted.

  Then, about the case of expansion ratio (omega) s, construction of test pile 10 'corresponding to the ready-made pile 10 is implemented (test pile construction process S25-3).

  Next, as described above, step S26-3 is performed, and then step S28-3 is performed through step S27-3. And it transfers to process S19 and implements this pile construction based on the case of the optimal expansion ratio omegaopt determined by process S28-3 and the optimal expansion excavation part length Lomegaopt.

  On the other hand, when it is determined in step S27-3 that the product of the design support force Rωs (measured value) and the number J of ready-made piles 10 is smaller than the product of the margin M and the design load (column load) P, As described above, step S27-3a and step S28-4 are performed.

  Then, it transfers to process S19 and implements this pile construction based on the case of the optimal expansion ratio omegaopt determined by process S28-4 and the optimal expansion excavation part length Lomegaopt.

  Thus, in this embodiment, since the loading test is performed from the test pile 10 'corresponding to the cost-priority expansion ratio ωc with a small expansion ratio ω at the construction site where the ready-made pile 10 is actually built, the actual construction site Therefore, the optimum enlargement ratio ω based on the results of the loading test can be surely obtained. For this reason, it is possible to set the optimum value ωopt of the enlargement ratio ω that does not become over-specification more efficiently based on the ground strength at the actual construction site. Further, since the loading test is performed from the test pile 10 ′ corresponding to the cost-prioritized enlargement ratio ωc, when the optimum enlargement ratio ωopt is set to a smaller value of the enlargement ratio ω, it corresponds to the enlargement ratio ω. It is possible to minimize the number of times the loading test of the design support force R is performed.

(Third embodiment)
Next, a schematic configuration of a cast-in-place pile provided by a foundation pile construction method according to another embodiment of the present invention will be described with reference to the drawings. FIG. 9: is a schematic block diagram which shows a part of pile foundation formed with the cast-in-place pile provided with the construction method of the foundation pile which concerns on other embodiment of this invention.

  In the present embodiment, the pile foundation 2 is formed by a cast-in-place pile 20 placed in a pile hole 23 excavated at a predetermined position in the ground GN, as shown in FIG. That is, a plurality of pile holes 23 are excavated at a predetermined position of the ground GN, and cast-in-place piles 20 are respectively casted by pouring concrete or the like into each pile hole 23, and the pile foundation 2 is formed by these cast-in-place piles 20. Is formed.

  In the cast-in-place pile 20 according to the present embodiment, a substantially conical diameter-enlarged portion 24 whose outer diameter increases downward is provided at the distal end portion 22a of the shaft portion 22 in order to ensure the distal end support force. Yes. In the present embodiment, the enlarged diameter portion 24 has an enlarged bulb shape whose outer diameter is larger than the inner diameter of the shaft portion 22 in order to ensure a larger tip support force. In order to form such an enlarged bulb-like enlarged diameter portion 24, an enlarged excavation portion 25 having an enlarged inner diameter is formed on the bottom side of the pile hole 23 so as to have substantially the same shape as the enlarged diameter portion 24. The

  In the present embodiment, as shown in FIG. 9, the outer diameter De of the enlarged diameter portion 24 is substantially the same as the inner diameter De of the enlarged excavation portion 25. The axial length Ld of the expanded diameter portion 24 is configured to be substantially the same as the expanded excavated portion length Lω that is the axial length of the expanded excavated portion 25.

  Moreover, in order to ensure the desired tip supporting force of the cast-in-place pile 20, the outer diameter De of the bottom portion 24a that is the maximum diameter portion of the expanded portion 24 with respect to the outer diameter Don of the shaft portion 22 of the cast-in-place pile 20, It is necessary to adjust the enlargement ratio ω indicating the ratio of the inner diameter De of the enlarged excavation part 25 excavated to form the enlarged diameter part 24. The expansion ratio ω is set to a design value based on predetermined data relating to the construction of the cast-in-place pile 20 such as a preliminary geological survey result, statistical data, and past construction data performed before the cast-in-place pile 20 is constructed. . However, when excavating the pile hole 23 at the actual construction site, the geological structure and soil quality of the ground GN may differ from the previous survey results, and the cast-in-place pile 20 is constructed with the set value of the expansion ratio ω as it is. Then, there is a possibility of generating overspec.

  In this way, the ground strength and the bearing capacity of the cast-in-place pile 20 are adapted in an environment where the geological structure and soil quality of the ground GN are different from the previous survey results, or in an environment where the ground strength is difficult to predict or where the ground strength varies greatly. It is difficult. That is, when the cast-in-place pile 20 is constructed, the geological condition of the ground GN is determined, and an appropriate depth L of the pile hole 23, an enlargement ratio ω of the enlarged excavation portion 25, and an enlarged excavation portion length Lω are set to optimum values. There is a need to.

  In particular, the enlargement ratio ω of the enlarged excavation part 25 is a value that determines the outer diameter De of the enlarged diameter part 24, and when the error between the design value and the actual measurement value is large, the so-called over-spec becomes a material. This is not preferable in terms of cost and construction work efficiency. In particular, since the outer diameter De of the enlarged diameter portion 24 is directly determined by the inner diameter De of the enlarged excavation portion 25, it is difficult to adjust the enlarged excavation portion 25 after excavation. In other words, it is very important to obtain the optimum value of the enlargement ratio ω of the enlarged excavating portion 25 in order to ensure the desired tip bearing force of the cast-in-place pile 20 without over-specifying. Further, in order to obtain the optimum value of the enlargement ratio ω, it is important to efficiently obtain the optimum value based on the result of the loading test on the ground GN that is the actual site.

  For this reason, in this embodiment, the construction method of the foundation pile by the construction system 100 (refer FIG. 2) mentioned above is implemented along the flow of FIG. 3, FIG. 5 thru | or FIG. 8 mentioned above, and it expands more efficiently and reliably. The optimum value of the ratio ω is obtained to reduce the overspec. Moreover, the over-spec at the time of placing the cast-in-place pile pile 20 in the ground GN is suppressed, the cost at the time of constructing the pile foundation 2 which consists of the cast-in-place pile 20 concerned is reduced, and construction work efficiency is improved. I am doing so.

In the present embodiment, the expansion ratio ω of the enlarged diameter portion 24, that is, the expansion ratio ω of the enlarged excavation portion 25, is set such that the inner diameter of the enlarged excavation portion 25 is De and the outer diameter Don of the shaft portion 22 of the cast-in-place pile 20 is outside. Since it is set as the diameter design value Ds, it is defined by the following equation (16).
ω = De / Don = De / Ds (16)

  That is, in the present embodiment, the outer diameter Don of the shaft portion 22 of the cast-in-place pile 20 is used as the outer-diameter design value Ds at a predetermined position of the tip portion 22a of the cast-in-place pile 20 used for calculating the enlargement ratio ω. In the present embodiment, the enlargement ratio ω is set, for example, in the range of 1.0 to 2.0, but the upper limit value of the enlargement ratio ω is not limited to 2.0.

  Further, the shape and the number of the enlarged diameter portions 24 provided in the cast-in-place pile 20 provided by the foundation pile construction method according to another embodiment of the present invention are not limited to the embodiment illustrated in FIG. That is, in the foundation pile construction method according to another embodiment of the present invention, as shown in FIG. 10, there are two substantially cylindrical enlarged diameter portions 34 and 36 on the bottom side of the shaft portion 32 of the cast-in-place pile 30. It is good also as a structure provided. Moreover, as shown in FIG. 11, the structure by which two substantially cylindrical diameter enlarged parts 44 and 46 which a side surface becomes a curved surface are provided in the bottom part side of the axial part 42 of the cast-in-place pile 40, or it shows in FIG. Thus, it is good also as a structure by which one substantially cylindrical enlarged diameter part 54 is provided in the bottom part side of the axial part 52 of the cast-in-place pile 50. FIG. In order to secure the tip support force of the cast-in-place piles 30, 40, 50, it is preferable to provide a plurality of stages of enlarged diameter portions 34, 36 as shown in FIG.

  Also in the case of constructing these cast-in-place piles 30, 40, 50, by applying the foundation pile construction method according to another embodiment of the present invention, the shaft portions 32, 42, 52 that are the outer diameter design values are applied. Optimum of the expansion ratio ω of the outer diameter of the enlarged diameter portions 34, 36, 44, 46, 54 with respect to the outer diameter Don, that is, the inner diameter De of the enlarged excavated portions 35, 37, 45, 47, 55 of the pile holes 33, 43, 53 The value can be obtained efficiently and reliably.

  Although each embodiment of the present invention has been described in detail as described above, it is easily understood by those skilled in the art that many modifications can be made without departing from the novel matters and effects of the present invention. It will be possible. Therefore, all such modifications are included in the scope of the present invention.

  For example, a term described with a different term having a broader meaning or the same meaning at least once in the specification or the drawings can be replaced with the different term in any part of the specification or the drawings. Further, the construction of the foundation pile construction system and the operation of the foundation pile construction method are not limited to those described in the embodiments of the present invention, and various modifications can be made.

1, 2, Pile foundation, 3, 23, 33, 43, 53 Pile hole 5, 25, 35, 37, 45, 47, 55 Expanded excavation part, 10 Ready-made pile (foundation pile), 10 'Test pile, 10a Tip Part, 10b outer peripheral surface, 12 convex part, 14 root consolidation part, 20, 30, 40, 50 cast-in-place pile (foundation pile), 22, 32, 42, 52, shaft part, 22a tip part, 24, 34, 36 , 44, 46, 54 Expanded part, 100 (foundation pile) construction system, 101 computer, 102 storage part, 104 storage medium, 106 RAM, 108 ROM, 110 CPU (calculation part), 112 setting part, 114 determination part , 116 determining unit, 120 input unit, 122 output unit, 124 communication unit, 125 system bus, 126 Internet, 128 design bearing capacity measuring device, 130 excavating device, 131 excavating Rod, 132 excavation blade, 134 movable excavation part, S13, S14 setting step, S16 design support force measurement step, S17, S17-1 design support force judgment step, S17-1a predictive design support force estimation step, S17-1b predictive design Supporting force determination step, S18 optimum enlargement ratio determination step, S19 enlargement excavation part formation step

Claims (10)

A construction method of a foundation pile in which a foundation pile is provided in a pile hole in which an enlarged excavation part with an enlarged inner diameter is formed on the bottom side,
A setting step of setting a plurality of expansion ratios indicating different ratios of the inner diameter of the expanded excavation portion with respect to the outer diameter design value at a predetermined position of the tip portion of the foundation pile;
Conducting a loading test for each case of one or a plurality of enlargement ratios selected from the plurality of enlargement ratios set in the setting step at the construction site where the foundation pile is actually provided, and the one or more enlargements A design bearing capacity measuring step for measuring the design bearing capacity of the foundation pile in each ratio;
For each of the one or a plurality of the design support forces measured in the loading test carried out at the construction site in the design support force measurement step, the product of the design support force and the number of foundation piles to be used, A design supporting force judgment step for judging whether or not a desired design load or more acting on a pile foundation formed by the foundation pile;
When measuring the design support force of the foundation pile at the one enlargement ratio in the design support force measurement step, when the condition that the product is equal to or more than the desired design load is satisfied in the design support force determination step In the case where the one enlargement ratio is determined as the optimum enlargement ratio for forming the enlarged excavation part, and the design support force of the foundation pile at the plurality of enlargement ratios is measured in the design support force measurement step. In the design support force determination step, the optimum enlargement for determining the smallest enlargement ratio among the enlargement ratios that satisfy the condition that the product is not less than the desired design load as the optimum enlargement ratio for forming the enlarged excavation part. A ratio determining step;
An expanded excavation portion forming step of forming the expanded excavation portion based on the optimum expansion ratio,
As the plurality of enlargement ratios in the setting step,
The optimum value based on predetermined data including at least soil data obtained in advance by ground survey at the construction site where the foundation pile is actually provided, measurement data of the load test described above, and past construction performance data of the foundation pile The set design value enlargement ratio and
An upper magnification ratio obtained by adding a predetermined value to the design value magnification ratio;
A foundation pile construction method, wherein a lower expansion ratio obtained by subtracting a predetermined value from the design value expansion ratio is set. In the setting step, when setting the plurality of enlargement ratios,
Setting a safety factor and a design support force for at least the design value magnification ratio, the upper magnification ratio, and the lower magnification ratio, respectively, based on the predetermined data;
Calculating the ultimate support force of the foundation pile by integrating the design support force and the safety factor corresponding to the design value enlargement ratio, the upper enlargement ratio, and the lower enlargement ratio, and
The foundation pile construction method according to claim 1, further comprising: calculating the design value expansion ratio, the upper expansion ratio, and the lower expansion ratio that satisfy the ultimate support force. In the setting step, when setting the plurality of enlargement ratios,
Calculating the design value enlargement ratio, the upper enlargement ratio, and the lower enlargement ratio according to the ratio of the design support force calculated by a predetermined formula and the design support force measured by the load test described above. The construction method of the foundation pile of Claim 1 characterized by these. In the design support force determination step, it is determined whether a product of the design support force measured based on the design value expansion ratio and the number of the foundation piles is equal to or more than the desired design load; When the product is greater than or equal to the desired design load in the design support force determination step,
Calculate at least the difference between the design support force measured in the design support force measurement step and the design support force calculated for the design value enlargement ratio set in the setting step, and calculate the lower enlargement ratio A predicted design support force estimating step of estimating a predicted design support force by correcting the magnitude of the difference with respect to the designed support force;
Prediction for determining whether or not the predicted design support force calculated in the predicted design support force estimation step is larger than the design support force measured based on the design value expansion ratio in the design support force measurement step A design support capacity determination process;
The foundation pile construction method according to claim 1, further comprising:   In the design support force determination step, is a product of the design support force and the number of foundation piles measured for each of the plurality of expansion ratios in the support force measurement step equal to or greater than the desired design load? The foundation pile construction method according to claim 1, wherein whether or not the plurality of enlargement ratios are small is determined in order. The foundation pile is a ready-made pile built into the pile hole,
The said design process WHEREIN: A desired clearance value is added to the outer diameter of the convex part provided in the outer peripheral surface of the front-end | tip part of this ready-made pile, and the said outer diameter design value is calculated | required. The construction method of the foundation pile of any one of 5. The foundation pile is cast in the pile hole, and is a cast-in-place pile in which a diameter-expanded portion is provided at the tip of the shaft portion,
The construction method for a foundation pile according to any one of claims 1 to 5, wherein, in the design step, an outer diameter of the shaft portion is set as the outer diameter design value.   The program for making a computer perform the construction method of the foundation pile of any one of Claim 1 thru | or 7.   A storage medium storing a computer-readable program for causing a computer to execute the foundation pile construction method according to any one of claims 1 to 7. A foundation pile construction system in which a foundation pile is provided in a pile hole in which an enlarged excavation part with an enlarged inner diameter is formed on the bottom side,
Database of predetermined data including at least soil data obtained in advance by ground survey at the construction site where the foundation pile is installed, measurement data of a loading test carried out at the construction site, and past construction performance data of the foundation pile A storage unit for storing and
An arithmetic processing unit for calculating an expansion ratio indicating a ratio of an inner diameter of the expanded excavation portion with respect to an outer diameter design value at a predetermined position of a tip portion of the foundation pile by performing calculation processing with a computer based on at least the predetermined data;
A design value expansion ratio that is included in the calculation unit and is set to an optimum value based on the predetermined data as the expansion ratio based on at least the predetermined data, and a predetermined value is added to the design value expansion ratio An upper magnification ratio, a lower magnification ratio obtained by subtracting a predetermined value from the design value magnification ratio, and a setting unit that sets a plurality of different values,
The number of the foundation piles to be used with the design support force, which is included in the calculation unit and measured by the loading test of the case of one or a plurality of enlargement ratios selected from the plurality of enlargement ratios set by the setting unit And a determination unit for determining whether or not the product is equal to or greater than a desired design load acting on a pile foundation formed by the foundation pile,
When the design support force at the one enlargement ratio is measured in the load test described above, the one enlargement ratio is satisfied when the product satisfies a condition that the product is equal to or greater than the desired design load. Is determined as the optimum expansion ratio for forming the expanded excavation part, and the design support force at the plurality of expansion ratios is measured in the load test described above, at least the determination unit determines that the product is the desired design. A foundation pile construction system, comprising: a determination unit that determines a minimum expansion ratio among the expansion ratios that satisfy a condition equal to or greater than a load as an optimal expansion ratio for forming the expanded excavation unit.

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