JP6315787B2 - Piled raft foundations for small structures - Google Patents

Description

  This invention belongs to the technical field of a piled raft foundation structure for a small-scale structure having a structure in which the weight of the small-scale structure is directly borne by a foundation (solid foundation) and a plurality of settlement reduction piles. The present invention relates to a piled raft foundation structure in which a foundation is directly supported by a plurality of settlement settlement piles having the same shape and the same bearing capacity.

  The piled raft foundation is intended to improve the performance of the entire foundation by using both the direct foundation and the settlement settlement pile. Its application range is recognized not only as a large (high-rise) structure but also as a foundation for small-scale structures typified by detached houses, and its application has been attempted in recent years.

When applying piled raft foundations to large structures, construction of subsidence-reducing piles with appropriate changes in pile diameter and pile length according to the installation site in order to respond rationally to changes in building loads, etc. To do is usually done.
However, when applying piled raft foundations to small-scale structures such as detached houses, the ease of pile design and pile construction is emphasized, and it is necessary to consider construction equipment and cost constraints. . Therefore, changing the design of the pile diameter and the pile length (especially the pile diameter) as appropriate according to the installation site is not usually performed because it is cumbersome, cumbersome, and error-prone. A predetermined number of settlement-reducing piles having a supporting performance of (1) were constructed (placed) in about half a day. Specifically, the pile design that can be said to be excessive according to the pile diameter and pile length of the settlement settlement pile constructed at the center (center of gravity) of the structure that requires the most support performance is made. Was built mechanically (placed) in about half a day, one below each pillar.

  By the way, the above-described pile design for large and small structures is not unique to piled raft foundations, and is also routinely performed even for pile foundations.

For example, Non-Patent Document 1 discloses a pile design in which a foundation beam form is adopted for a pile foundation of a wooden house that is rectangular in plan view, and nine piles are arranged in a balanced manner in three rows and three columns. Yes.
According to this pile design, it is possible to reduce the number of piles required for 32 fabric foundations and solid foundations used in general wooden house foundations to 9, so economical pile design for wooden houses is possible. The statement that it will be possible is permitted.

Further, Patent Document 1 discloses an invention relating to a composite ground design method including a raw ground supporting a detached house and a small-diameter pile installed in the raw ground. As an example, nine small-diameter piles 4 arranged in three rows and three columns are disclosed in FIGS. The nine small-diameter piles 4 are provided under each column 1 (see paragraph [0047] of the same document 1).
According to this Patent Document 1, it is possible to realize an optimum design of a composite ground composed of a (small diameter) pile and an original ground, and thus, a composite ground that is as cheap as possible and sufficiently safe is ensured. The statement that it can be designed is recognized (see the paragraph [0042]).

Asahi Kasei Construction Materials EAZET Construction Method [URL: http://www.asahikasei-kenzai.com/akk/eazet/utilization_and_result/use/build02.html JP2011-12510A

According to Non-Patent Document 1, an economical pile design can be realized, and according to Patent Document 1, an optimum design of a composite ground composed of a pile and an original ground can be realized, but these inventions are common. Therefore, the idea and technical idea that the number of piles is less than or less than the number of pillars is strictly attached to the technical idea of building (laying) one pile under every pillar. There is no disclosure or suggestion.
Therefore, if the number of piles can be further reduced compared to the case where one pile is placed under each pillar while maintaining the soundness of small-scale structures represented by detached houses, the economy and construction It is clear that it is beneficial in terms of sex.

  Accordingly, the object of the present invention is to reduce the number of piles even if the number of piles is reduced, compared to piled raft foundations, where one subsidence-reducing pile is constructed directly under the foundation of all pillars of a small-scale structure. Small scale structure with excellent economic efficiency and workability by realizing rational pile design (structural design) that maintains the overall soundness and maximizes the resistance of the ground directly to the bottom of the foundation. It is to provide a piled raft foundation structure for use.

As a means for solving the above-mentioned background art problem, the piled raft foundation structure for a small-scale structure according to the invention described in claim 1 is characterized in that the weight of the small-scale structure is directly reduced to a plurality of settlement reduction piles. It is a piled raft foundation structure for small-scale structures with a structure to bear
Each of the plurality of settlement reduction piles has an equivalent supporting force,
The plurality of settlement reduction piles are arranged in an outer peripheral part of the small-scale structure and an inner part inside the outer peripheral part,
Compared with the case where one subsidence reduction pile is arranged under each pillar of the small-scale structure, the number of subsidence reduction piles arranged on the outer peripheral part is reduced, and the subsidence reduction piles are arranged on the outer peripheral part of the small-scale structure. the floor space subsidence reduction piles share, said by subsidence reduced pile placed inside portion to expand so as to approach the floor area to be shared, one by one subsidence reduced pile under each pillar of the small structure characterized by being configured to support the spread foundation with a small quantity settlement reduce pile than when disposing.

The piled raft foundation structure for a small-scale structure according to the invention described in claim 2 is a pile for a small-scale structure having a structure in which the weight of the small-scale structure is directly borne by the foundation and the plurality of settlement reduction piles. -Raft basic structure,
Each of the plurality of settlement reduction piles has an equivalent supporting force,
The pillars of small structures, and the outer columns disposed in the outer peripheral portion is divided into an inner pillar other than the outer peripheral pole, if the ratio of the arranged one by one subsidence reduced pile under each pillar of small structures The subsidence reduction pile is arranged under or near one outer peripheral column, and arranged in the outer peripheral part in a configuration in which no other subsidence pile is arranged in the other outer peripheral column adjacent to the one outer peripheral column. the floor space subsidence reduced pile to place the outer peripheral portion of the small-scale structure by reducing the number of reduction piles are shared, subsidence reduction piles placed under said pillars to expand so as to approach the floor area to share it is characterized in that it has a structure for supporting the spread foundation with settlement reducing piles of smaller quantities than the case of disposing one by one subsidence reduced pile under each pillar of the small structure.

A piled raft foundation structure for a small-scale structure according to the invention described in claim 3 is a pile structure for a small-scale structure having a structure in which the weight of the small-scale structure is borne by the direct foundation and a plurality of settlement-reducing piles. -Raft basic structure,
Each of the plurality of settlement reduction piles has an equivalent supporting force,
The pillars of the small-scale structure are arranged at predetermined intervals in the vertical and horizontal directions when viewed from the plane direction.
Divide the floor area of a small-scale structure into multiple divided areas of almost the same shape and size with virtual lines crossing the center between columns that are adjacent vertically and horizontally, and one subsidence reduction pile under each column Assuming that
The pillars of small structures, and the outer columns disposed in the outer peripheral portion is divided into an inner pillar other than the outer peripheral pole, one of four divided areas around the one of the inner pillars under the inner pillar as a reference to subsidence reduced piles sharing, the floor area of a single settlement reducing pile beneath or near the one outer peripheral pillars are shared, the other outer peripheral columns adjacent to the one outer peripheral pillars of By reducing the number of settlement-reducing piles placed on the outer periphery in a configuration without placing settlement-reducing piles, the floor area corresponding to the four divided areas shared by one settlement-reducing pile under the inner pillar is expanded. be to, characterized in that a structure for supporting the spread foundation with settlement reducing piles of smaller quantities than the case of disposing one by one subsidence reduced pile under each pillar of the small structure.

The piled raft foundation structure for a small-scale structure according to the invention described in claim 4 is a pile for a small-scale structure having a structure in which the weight of the small-scale structure is directly borne by the foundation and the plurality of settlement-reducing piles. -Raft basic structure,
Each of the plurality of settlement reduction piles has an equivalent supporting force,
The pillars of the small-scale structure are arranged at predetermined intervals in the vertical and horizontal directions when viewed from the plane direction.
Assuming that one subsidence-reducing pile is placed under each pillar of the small-scale structure, it is placed on the four side edges excluding the four corners among the outer-circular pillars placed on the outer circumference of the small-scale structure. For the outer peripheral column, by reducing the number of subsidence reduction piles arranged in the outer peripheral part in a configuration in which no subsidence reduction piles are arranged under at least one outer peripheral column with respect to one side part, by subsidence reduced pile arranged in the vicinity thereof to enlarge the floor area to be shared, the direct sinking reduce pile quantities less than if the arranging one by one subsidence reduced pile under each pillar of small structures It is characterized by having a structure that supports the foundation.

The invention described in claim 5 is the piled raft foundation structure for a small-scale structure according to any one of claims 2 to 4, and the vicinity under the outer peripheral column in which the settlement reduction pile is arranged. It is a central part between adjacent outer peripheral columns and outer peripheral columns.
The invention described in claim 6 is the piled raft foundation structure for a small-scale structure according to any one of claims 2 to 4, wherein the outer peripheral column on which the settlement reduction pile is arranged is a four-corner column. It is characterized by that.

The invention described in claim 7 is the piled raft foundation structure for a small-scale structure according to any one of claims 1 to 6, wherein the settlement reduction piles are equivalent in each having the same pile diameter and pile length. It is characterized by having a supporting force of
The invention described in claim 8 is a piled raft foundation structure for a small-scale structure according to any one of claims 1 to 7, wherein the small-scale structure is a unit type detached house. It is characterized by.

According to the piled raft foundation structure for small-scale structures according to the present invention, compared to the piled raft foundation structure in which one subsidence reducing pile is constructed directly through the foundation at the lower position of all columns, Even if the number is reduced, the soundness of the whole structure can be maintained, so it is very excellent in economic efficiency and workability. In addition, by reducing the number of piles, pile design (structural design) that maximizes the resistance of the ground directly on the bottom of the foundation can be realized, which is very reasonable.
In addition, pile design (pile length, pile diameter, and bearing capacity) is convenient because it can be obtained according to the guidelines for small-scale building foundation design published by the Architectural Institute of Japan as usual without using any special methods. .
Therefore, the simplicity of pile design and pile construction is emphasized, and it is extremely suitable for small-scale structures that require consideration of construction machines and cost constraints.

A is an elevation view (B-A arrow view of B) showing a piled raft foundation structure for a small-scale structure according to Example 1 of the present invention. It is a BB line arrow view of A). It is a pillar plan (plan view) showing a piled raft foundation structure for a small-scale structure according to Example 2 of the present invention. It is a columnar figure which showed the piled raft foundation structure for small-scale structures concerning Example 3 of this invention. It is the pillar plan which showed the piled raft foundation structure for the small-scale structures concerning Example 4 of this invention. It is the pillar plan which showed the piled raft foundation structure for small-scale structures concerning Example 5 of this invention. It is a columnar figure which showed the piled raft foundation structure for small-scale structures concerning Example 6 of this invention. It is the pillar plan which showed the piled raft foundation structure for small-scale structures concerning Example 7 of this invention. AD is explanatory drawing for demonstrating the effect of the piled raft foundation structure for small-scale structures concerning Example 4 of this invention. It is a pillar figure which showed the piled raft foundation structure for small-scale structures concerning a prior art.

The present invention is typically applied to ground where a Swedish raft foundation structure has been determined to be suitable by a Swedish Sounding (SWS) test. In general, when building a small-scale structure or the like requested by the owner, a pile (settlement-reducing pile) is used to reduce the amount of settlement and non-uniform settlement when the direct foundation alone does not satisfy the required design performance. ) Is often added directly to the foundation. For example, the case where the supporting ground as a direct foundation is relatively hard clay or high-density sand can be mentioned.
The small-scale structure and the like are almost synonymous with the small-scale building defined in the “Small Building Basic Design Guidelines” (The Architectural Institute of Japan). Incidentally, the small-scale building is defined as satisfying the conditions of 3 floors or less above the ground, building height of 13 m or less, eave height of 9 m or less, and total area of 500 m ² or less in the guidelines.
The burden ratio between the direct foundation and the settlement reduction pile is appropriately changed based on the ground properties. Usually, there are many cases where a structural design that can bear about 50% each is aimed. Moreover, the joint of a direct foundation and a settlement reduction pile may be rigidly connected, and may be pin-joined. In the case of exhibiting a behavior close to rigid connection, a configuration in which the foundation is simply placed directly on the pile head can also be implemented.

Here, the basic principle of the present invention (how the applicants have arrived at the technical idea of the present invention) will be described.
As shown in FIG. 9, when a foundation suitable for a small-scale structure (detached house) 10 is implemented with a piled raft foundation structure 3 including a direct foundation 1 and a settlement reduction pile 2, a conventional pile design is In general, it is performed on the assumption that the settlement reduction piles 2 are arranged (provided) one by one under all the pillars 4 (see, for example, Non-Patent Document 1 and Patent Document 1). And each subsidence reduction pile 2 matched the pile design (pile diameter, pile length, and supporting force) of the subsidence reduction pile 2 arrange | positioned in the center (gravity center) part by which support performance is requested | required most. The reason is as described in the background section.
However, the floor area (building load) shared by one subsidence reduction pile 2 differs greatly depending on the installation site of the pile 2. For example, if the floor area of the small-scale structure 10 according to FIG. 9 is divided into approximately 16 equal parts by a virtual line (dashed line) crossing the center between the pillars 4 adjacent to each other vertically and horizontally, the building load is even. Assuming that there is a subsidence reduction pile 21 arranged below the central column 4, the subsidence reduction piles 22 arranged below the side columns 4 are 2 Only one divided area β is borne, and the settlement reduction pile 23 arranged below the four corner pillars 4 bears only one divided area γ.
Then, since the settlement reduction piles 22 and 23 have the same supporting force as the settlement settlement pile 21, according to simple calculation, the settlement reduction pile 22 is 1 in comparison with the settlement reduction pile 21. Only the support force of / 2 is exhibited, and the settlement reduction pile 23 exhibits only the support force of 1/4.
That is, it can be said that the subsidence reduction piles 22 and 23 have an excessive pile design.

  In the first place, the piled raft foundation structure 3 is a structure that allows the subsidence of the subsidence reduction pile 2 to some extent and directly expects the resistance of the ground on the bottom surface of the foundation 1, so such an excessive pile design is too uneconomic . In other words, it is not a pile design (structural design) that makes full use of the resistance force of the ground directly on the bottom surface of the foundation 1.

  Therefore, when it is assumed that the subsidence reduction piles 22 are not disposed below the side pillars 4, that is, for example, in the configuration of Example 1 below (see FIG. 1), the subsidence disposed below the four corner columns 4. As for the reduction pile 23, the area to bear is expanded. In other words, three divided (γ + 2β) divided areas, which are a combination of one divided area γ and two divided areas β on both the left and right sides, are borne. Still, according to simple calculation, each of the four settlement reduction piles 23 arranged below the four corner pillars 4 exhibits only 3/4 of the supporting force compared to the settlement settlement piles 21 arranged below the central pillar 4. Will not be.

  From the above, the present applicants are not limited by the concept (technical idea) of placing one settlement-reducing pile 2 under each pillar 4 of the small-scale structure 10, and the number of piles is compared with that concept. It was judged that a piled-raft foundation structure with sufficient soundness was feasible even if it was reduced.

  Next, an example of a piled raft foundation structure for a small-scale structure according to the present invention will be described with reference to the drawings.

1A and 1B show an embodiment of a piled raft foundation structure for a small-scale structure according to the present invention.
The piled raft foundation structure 3 according to the first embodiment is configured so that the weight of the small-scale structure 10 is directly borne by the foundation 1 and the plurality of settlement reduction piles 2. Has the same supporting force. In addition, the plurality of settlement reduction piles 2 are arranged on the outer peripheral part of the small-scale structure 10 and the inner part on the inner side of the outer peripheral part, and below each pillar 4 of the small-scale structure 10. The subsidence reduction piles 2 arranged on the outer peripheral part of the small-scale structure 10 are shared by reducing the quantity of the subsidence reduction piles 2 arranged on the outer peripheral part as compared with the case where the subsidence reduction piles 2 are arranged one by one. By expanding the floor area to be (burdened) closer to the floor area shared by the settlement reduction piles 2 arranged on the inner side (in the illustrated example, the center part (center of gravity)) from the outer peripheral part, the small-scale structure 10 It is set as the structure which supports the foundation 1 directly by the subsidence reduction pile 2 of a quantity smaller than the case where one subsidence reduction pile 2 is arrange | positioned under each pillar 4 of each.

Specifically, the pillars 4 (9 in the illustrated example) of the small-scale structure 10 are arranged on the outer peripheral part (eight in the illustrated example) 4 and inner pillars (in the illustrated example) other than the outer peripheral pillars. divided into one) 4 and the comparison with the case of arranging one by one subsidence reduced pile 2 to each column 4 below the small structure 10, subsidence into one under the outer peripheral column 4 (or its vicinity) Decrease reduction placed in the outer peripheral portion in a configuration in which the reduction pile 2 is arranged and the subsidence reduction pile 2 is not arranged under another outer peripheral column 4 (side column 4 in the illustrated example) adjacent to the one outer peripheral column 4 By reducing the number of piles 2, the floor area shared by the settlement settlement piles 2 arranged on the outer periphery of the small-scale structure 10 is shared by the settlement settlement piles 2 arranged below one inner pillar 4. be to enlarge to approach, less than the case of disposing one by one subsidence reduced pile 2 to each column 4 below the small structure 10 It is set as the structure which supports the foundation 1 directly with the quantity of settlement reduction piles 2 (five in the example of illustration).

More specifically, the pillars 4 of the small-scale structure 10 are arranged at predetermined intervals (about 5 m in the illustrated example) in the vertical and horizontal directions when viewed from the plane direction. Divided into a plurality of (16 in the illustrated example) divided areas of approximately the same shape and size by imaginary lines (dashed lines) crossing the center between the pillars 4 adjacent to each other in the vertical and horizontal directions. Assuming that piles 2 are placed one by one,
With reference to the fact that one subsidence reduction pile 2 under the inner pillar 4 shares four divided areas (refer to the symbol α) centered on one inner pillar 4, the outer peripheral pillar 4 (corner pillar 4) The floor area (see symbol γ) shared by one subsidence reduction pile 2 below (or in the vicinity thereof) subsidizes under another outer peripheral column 4 (side column 4) adjacent to the one outer peripheral column 4 By reducing the number of settlement reduction piles 2 arranged on the outer periphery in a configuration in which the reduction piles 2 are not arranged, the floor area corresponding to four divided areas shared by one settlement settlement pile 2 below the inner pillar 4 is achieved. approach seems to be enlarged (divided areas on both sides of the divided area gamma beta (3 three divided areas of the angle-shaped including a see FIG. 9)), the subsidence reduced pile 2 to each column 4 under the small-scale structure 10 1 The foundation 1 is directly supported by subsidence reduction piles 2 (five in the illustrated example) that are smaller than the case of arranging them one by one We are trying to be.
Each of the five subsidence reduction piles 2 has substantially the same pile diameter and pile length (that is, the same shape and the same size), and has an equivalent supporting force. The settlement reduction pile used in the present invention preferably has a pile diameter (φ) of about 100 to 300 mm, a pile length (L) of about 5.0 to 15.0 m, and an ultimate supporting force (Ru) of about 50 to 150 kN. . Incidentally, in this embodiment, as an example, the pile diameter is 200 mm, the pile length is 8.0 m, and the pile supporting force is 84.3 kN.

Regarding the column design of a small-scale structure, in this embodiment, on the assumption that the columns 4 are aligned and arranged at a predetermined interval, the size (particularly the floor area), weight, etc. of the small-scale structure 10 to be constructed are set. The arrangement and number of columns (that is, column allocation) are determined by structural design based on conditions. In addition, the rigidity (member cross section) of the column 4 is determined.
By the way, the small-scale structure 10 according to the first embodiment is assumed to be a detached house, the building area is about 10 m × 10 m, and the column 4 has two column spans equivalent to each other in the beam-to-beam direction and the cross-beam direction. It is implemented with a total of 9 rows of 3 rows and 3 columns.
Out of the eight outer peripheral columns 4 arranged at the outer peripheral portion among the nine columns 4, the four outer peripheral portions arranged at the side portions excluding the four outer peripheral columns (four corner columns) 4 arranged at the four corner portions. For the pillars (side pillars) 4, the subsidence reduction pile 2 is not arranged at the lower position, and the direct foundation is placed below the remaining five pillars 4 (four corner pillars 4 and one central pillar 4). 1 to determine the structure in which the settlement reduction pile 2 is disposed.

  The pile design (pile length, pile diameter, and supporting force) per one of the subsidence reduction piles 2 is implemented with a configuration in which one pile is arranged under one pillar with respect to the nine pillars 4. In this case, the decision is made based on the guidelines for small-scale building foundation design published by the Architectural Institute of Japan. Moreover, the said pile design is set as the pile design match | combined with the support power of the settlement reduction pile 2 arrange | positioned in the center (center of gravity) part of the structure where support performance is most required. About the said pile design, it is set as the same technical idea also about the following Examples.

Therefore, the piled raft foundation structure 3 according to the first embodiment is based on the above-described pile design (pile specifications), and the center pillar 4 and the four corner pillars 4 among the nine pillars 4 provided in the detached house 10 to be constructed. A total of five subsidence reduction piles 2 are mechanically constructed (placed) in the shape of 5 dice at a position corresponding to the lower part of the dice. Next, the foundation 1 is constructed directly on the pile head of the subsidence reduction pile 2 to form a piled raft foundation structure 3. Thereafter, the detached house 10 having nine pillars 4 on the direct foundation 1 is constructed.
According to the piled raft foundation structure 3 of the above configuration, the number of piles is reduced by 4 compared to the piled raft foundation structure in which one subsidence reduction pile is constructed directly through the foundation at the lower position of all columns. Can be implemented.
The reason why this Example 1 determined that a piled raft foundation structure having sufficient soundness even with five subsidence reduction piles can be realized with respect to the number of pillars (9) is the above [for carrying out the invention] As described in the section of [Forms] (see paragraphs [0019] to [0022]).

  In addition, the present applicants conducted a full-scale experiment with the variation arrangement of FIG. 4 in order to confirm that the above judgment was correct. As a result, it was convinced that a piled raft foundation structure with sufficient soundness could be realized even if the number of piles was reduced relative to the number of pillars. This experiment will be described later (see paragraphs [0062] to [0066]).

Therefore, according to the piled raft foundation structure 3 of the first embodiment according to the present invention, even the five subsidence reduction piles 2 have the subsidence reduction piles 2 under all the pillars 4 of the small-scale structure 10. Since it can be said that the soundness of the whole structure can be maintained as in the case of a piled raft foundation in which nine are arranged one by one, it is very excellent in economy and workability as compared with the conventional case.
Moreover, by reducing the number of piles, a pile design (structural design) that makes full use of the resistance of the ground directly on the bottom surface of the foundation 1 can be realized.
In addition, pile design (pile length, pile diameter, and bearing capacity) is convenient because it can be obtained according to the guidelines for small-scale building foundation design published by the Architectural Institute of Japan as usual without using a special method.

FIG. 2 shows a different embodiment of a piled raft foundation for a small scale structure according to the present invention.
The piled raft foundation structure 3 according to the second embodiment is for the small-sized structure 20 that is slightly longer in the direction of the digit than the first embodiment, and according to this, the form of the foundation 1 is directly enlarged. Although it is different, the pile specifications, the number of piles, and the pile arrangement are the same as those in the first embodiment.
Therefore, according to the piled raft foundation structure of the second embodiment, the total number of pillars 4 of the small-scale structure (detached house) 20 is nine as in the first embodiment, whereas the The total number of subsidence reduction piles 2 of the raft foundation structure 3 can be implemented with five, and compared to the case where one subsidence reduction pile 2 is arranged under each pillar 4 of the conventional small-scale structure 20, one subsidence reduction pile Since it can be said that equivalent support performance can be realized even if the total number of 2 is reduced by four, it is reasonable, and is excellent in economic efficiency and workability.

FIG. 3 shows a different embodiment of a piled raft foundation for a small structure according to the invention.
The piled raft foundation structure 3 according to the third embodiment is for the small-sized structure 30 that is longer in the column direction than the second embodiment, and the form of the foundation 1 is directly enlarged accordingly. . Moreover, although the pile specification is the same, the number of piles and pile arrangement | positioning are changed as shown in FIG.
In addition, since members, such as the said subsidence reduction pile 2 and the pillar 4, are the same as that of the said Example 1, the same code | symbol is attached | subjected and the description is abbreviate | omitted suitably.

  That is, the piled raft foundation structure 3 is configured such that the pillars 4 of the small-scale structure 30 are arranged at predetermined intervals (about 5 m in the illustrated example) in the vertical and horizontal directions when viewed from the plane direction. Based on the idea (see paragraphs [0024] to [0026]), in order to enlarge the floor area shared by the settlement reduction piles 2 arranged under the outer column (four corner columns) 4, it is arranged on the outer periphery of the column 4 Out of the outer peripheral pillars 4, at least one outer peripheral pillar 4 arranged on the side part excluding the four corners (one in the inter-beam direction and two in the row direction in the illustrated example) for each side part. By not arranging the settlement-reducing piles 2 below, the total number of settlement-reducing piles 2 (six in the illustrated example) is equal to the total number of pillars 4 (12 in the illustrated example). ) The foundation 1 was directly supported with a smaller quantity.

The column design of the small-scale structure 30 is based on various conditions such as the size (particularly the floor area) and the weight of the small-scale structure 30 to be constructed on the assumption that the columns 4 are arranged at predetermined intervals. The arrangement and number of columns (that is, column allocation) are determined by the structural design. In addition, the rigidity (member cross section) of the column 4 is determined.
Incidentally, the small-scale structure 30 according to the third embodiment is assumed to be a detached house, the building area is about 10 m × 15 m, and the column 4 has two column spans in the beam-to-beam direction and columns in the column direction. A total of 12 spans of 3 rows and 4 columns with 3 spans are implemented.
Next, of the 12 columns 4, of the 10 outer columns 4 arranged on the outer periphery, the six columns provided on the side portions excluding the four outer columns (four corner columns) 4 provided at the four corners. The outer pillars (side pillars) 4 do not have the settlement reduction piles 2 disposed below them, and are directly below the remaining six pillars 4 (four four-corner pillars 4 and two inner pillars 4). The structure in which the settlement subsidence pile 2 is arranged through the foundation 1 is determined.

Therefore, the piled raft foundation structure 3 according to the third embodiment has a total of six in the position corresponding to the lower side of the inner pillar 4 and the four corner pillars 4 among the twelve pillars 4 provided in the detached house 30 to be constructed. The subsidence reduction pile 2 is mechanically constructed. Next, the foundation 1 is constructed directly on the pile head of the subsidence reduction pile 2 to form a piled raft foundation structure 3. Thereafter, the detached house 30 having 12 pillars 4 on the direct foundation 1 is constructed.
Thus, according to the piled raft foundation structure 3 according to the third embodiment, as compared with the piled raft foundation structure in which one subsidence reducing pile is constructed directly through the foundation at the lower position of all columns, The number of piles can be reduced by half.

Here, the floor area which one subsidence reduction pile 2 bears (shares) with respect to the floor area of the small-scale structure 30 is examined.
According to the first embodiment, the floor area of the small-scale structure 30 is divided into approximately 24 equal parts by an imaginary line (dashed line) crossing the center between the pillars 4 adjacent to each other in the vertical and horizontal directions. If the settlement reduction piles 2 are arranged under all the pillars 4 and implemented, the settlement reduction piles 2 arranged under the inner pillars 4 bear four divided areas, whereas the side pillars 4 The subsidence reduction pile 2 arranged underneath bears only two divided areas, and the subsidence reduction pile 2 arranged under the four corner pillars 4 bears only one divided area.
Then, the settlement reduction pile 2 disposed below the side pillars 4 and the four corner pillars 4 has a supporting force equivalent to that of the settlement reduction pile 2 disposed below the inner pillar 4. Similarly, the settlement reduction pile 2 arranged below the side pillar 4 exhibits only a half supporting force, and the settlement reduction pile 2 arranged below the four corner pillars 4 supports 1/4. It means that only power is demonstrated. In other words, it can be said that excessive pile design is made accordingly.

Therefore, if it is assumed that the subsidence reduction piles 2 are not disposed below the side pillars 4, that is, the structure of the third embodiment (see FIG. 3), the subsidence disposed below the inner pillars 4 is simply calculated. The reduced pile 2 bears four divided areas that form a square shape as a whole, and the subsidence reduced pile 2 provided below the four corner posts 4 has four divided areas that form an L shape as a whole (see the hatched portion in FIG. 3). Will bear.
Then, the settlement reduction piles 2 provided below the inner pillars 4 and the four corner pillars 4 have the same floor area, but the number of piles 2 is the same as in the first and second embodiments. It was judged that a piled-raft foundation structure with sufficient soundness was feasible even if it was reduced.

  Therefore, according to the piled raft foundation structure 3 of Example 3, the total number of the pillars 4 of the small-scale structure (detached house) 30 is 12, whereas the settlement reduction pile of the piled raft foundation structure 3 The total number of 2 can be implemented with 6, and compared to the case where the settlement settlement piles are arranged under all the conventional pillars, the same support performance can be realized even if the total number of settlement settlement piles 2 is reduced by half. It can be said that it is reasonable, excellent in economic efficiency and workability.

FIG. 4 shows a different embodiment of a piled raft foundation for a small scale structure according to the present invention.
In the piled raft foundation structure 3 according to the example 4, the pillars 4 of the small-scale structure 40 have predetermined intervals in the vertical and horizontal directions as viewed from the plane direction (2.0 m in the vertical direction and 3.0 m in the horizontal direction). Based on the technical idea described above (see paragraphs [0024] to [0026]), the floor area shared by subsidence reduction piles 2 placed under (or in the vicinity of) outer pillar 4 is expanded. In order to make the outer peripheral pillars 4 arranged on the outer peripheral part of the pillar 4 at least one outer peripheral pillar 4 arranged on the side part excluding the four corners per side part (in the illustrated example, in the direction between the beams) By not arranging the settlement-reducing piles 2 below the outer peripheral pillars 4 (one, two in the row direction), the total number of settlement-reducing piles 2 (nine in the illustrated example) ) Directly supports the foundation 1 with a smaller number than the total number of the pillars 4 (15 in the illustrated example). It was.
Note that the column design and pile design of the small-scale structure 40 are determined based on the same technical idea as in the first to third embodiments, and are therefore omitted (see paragraphs [0027] and [0028] above).

Therefore, the piled raft foundation structure 3 according to the fourth embodiment has three inner pillars 4, four corner pillars 4, and columns (vertical) in the 15 pillars 4 provided in the detached house 40 to be constructed. A total of nine subsidence reduction piles 2 are mechanically constructed at positions corresponding to the lower side of the central two side pillars. Next, the foundation 1 is constructed directly on the pile head of the subsidence reduction pile 2 to form a piled raft foundation structure 3. Thereafter, the detached house 40 having 15 pillars 4 on the direct foundation 1 is constructed.
As described above, according to the piled raft foundation structure 3 according to the fourth embodiment, the piled raft foundation structure in which one subsidence reduction pile is constructed directly through the foundation at the lower position of all the conventional columns. However, the number of piles can be reduced by six.

Here, the floor area which one subsidence reduction pile 2 bears with respect to the floor area of the small-scale structure 40 is examined.
In accordance with the first embodiment, the floor area of the small-scale structure 40 is divided into approximately 32 equal parts by an imaginary line (dashed line) crossing the center between the pillars 4 adjacent to each other vertically and horizontally. If the settlement reduction piles 2 are arranged under all the pillars 4 and implemented, the settlement reduction piles 2 arranged under the inner pillars 4 bear four divided areas, whereas the side pillars 4 The subsidence reduction pile 2 arranged underneath bears only two divided areas, and the subsidence reduction pile 2 arranged under the four corner pillars 4 bears only one divided area.
Then, the settlement reduction pile 2 disposed below the side pillars 4 and the four corner pillars 4 has a supporting force equivalent to that of the settlement reduction pile 2 disposed below the inner pillar 4. Similarly, the settlement reduction pile 2 arranged below the side pillar 4 exhibits only a half supporting force, and the settlement reduction pile 2 arranged below the four corner pillars 4 supports 1/4. It means that only power is demonstrated. In other words, it can be said that excessive pile design is made accordingly.

Therefore, when it is assumed that the subsidence reduction piles 2 are not arranged below the side pillars 4, that is, in the configuration of the fourth embodiment (see FIG. 4), the three inner pillars 4 are simply calculated. The subsidence reduction piles 2 arranged below each of them bear four divided areas α, and the subsidence reduction piles 2 arranged below the four-corner pillars 4 each bear three divided areas γ, and the row (vertical) direction The two side pillars 4 at the center of each bear four divided areas β.
If it does so, the four settlement reduction piles 2 arrange | positioned under the four-corner pillar 4 will demonstrate only the support force of 3/4 compared with the settlement reduction pile 2 arrange | positioned under the inner pillar 4, respectively by simple calculation. There will be no. Moreover, since the two settlement reduction piles 2 arrange | positioned under the side pillar 4 are each exhibiting the support force equivalent to the settlement reduction pile 2 arrange | positioned under the inner pillar 4, said implementation As in Examples 1 to 3, it was determined that a piled raft foundation structure having sufficient soundness could be realized even if the number of piles 2 was reduced.

  Therefore, according to the piled raft foundation structure 3 of Example 4, the total number of pillars 4 of the small-scale structure (detached house) 40 is 15, whereas the settlement reduction pile of the piled raft foundation structure 3 The total number of 2 can be implemented with 9, and compared to the case where the settlement reduction piles are arranged under all the conventional pillars, the same support performance can be realized even if the total number of settlement reduction piles 2 is reduced by 6. It can be said that it is reasonable, excellent in economic efficiency and workability.

FIG. 5 shows a different embodiment of a piled raft foundation for a small scale structure according to the present invention.
In the piled raft foundation structure 3 according to the fifth embodiment, the pillars 4 of the small-scale structure 50 are arranged at predetermined intervals (about 5 m in the illustrated example) in the vertical and horizontal directions when viewed from the plane direction. Based on the technical idea (see paragraphs [0024] to [0026]), the outer peripheral portion of the pillar 4 is expanded in order to increase the floor area shared by the settlement reduction pile 2 disposed under (or in the vicinity of) the outer peripheral pillar 4 Among the outer peripheral columns 4 arranged at the side, the outer peripheral columns 4 arranged at the side portions excluding the four corners are positioned below the outer peripheral columns 4 at least one (all two in the illustrated example) per side portion. By not arranging the settlement reduction piles 2, the total number of settlement reduction piles 2 (eight in the illustrated example) is less than the total number of pillars 4 (16 in the illustrated example) by the amount that the settlement reduction pile 2 is not provided. In this configuration, the foundation 1 is directly supported.
Note that the column design and pile design of the small-scale structure 50 are determined based on the same technical idea as in the first to fourth embodiments, and are therefore omitted (see paragraphs [0027] and [0028] above).

Therefore, the piled raft foundation structure 3 according to the fifth embodiment has a position corresponding to the lower side of the four inner pillars 4 and the four corner pillars 4 among the 16 pillars 4 provided in the detached house 50 to be constructed. A total of eight settlement reduction piles 2 are mechanically constructed. Next, the foundation 1 is constructed directly on the pile head of the subsidence reduction pile 2 to form a piled raft foundation structure 3. Thereafter, the detached house 50 having 16 pillars 4 on the direct foundation 1 is constructed.
Thus, according to the piled raft foundation structure 3 according to the fifth embodiment, the number of piles is less than that of the piled raft foundation structure in which the settlement subsidence piles are constructed directly through the foundations at the lower positions of all columns. It can be reduced by half.

Here, the floor area which one subsidence reduction pile 2 bears with respect to the floor area of the small-scale structure 50 is examined.
If the floor area of the small-scale structure 50 is divided into approximately 36 equal parts by a virtual line (a dashed line) crossing the center between the pillars 4 adjacent to each other in the vertical and horizontal directions according to the first embodiment, all the pillars are assumed. When the subsidence reduction pile 2 is arranged under 4 and carried out, the subsidence reduction pile 2 arranged under the inner pillar 4 bears four divided areas, but is arranged below the side pillars 4. The subsidence reduction pile 2 which bears only two division areas, and the subsidence reduction pile 2 arrange | positioned under the four corner pillars 4 bears only one division area.
Then, the settlement reduction pile 2 disposed below the side pillars 4 and the four corner pillars 4 has a supporting force equivalent to that of the settlement reduction pile 2 disposed below the inner pillar 4. Similarly, the settlement reduction pile 2 arranged below the side pillar 4 exhibits only 1/2 support force, and the settlement reduction pile 2 provided below the four corner pillars 4 has 1/4 support force. However, it has only been demonstrated.

Therefore, when it is assumed that the subsidence reduction piles 2 are not arranged below the side pillars 4, that is, in the configuration of the fifth embodiment (FIG. 5), the simple calculation is arranged below the four inner pillars 4. The subsidence reduction piles 2 each bear four divided areas, and the subsidence reduction piles 2 arranged below the four-corner pillars 4 bear five divided areas (see shaded portions) that form an angle shape as a whole. Become.
Then, the settlement reduction pile 2 arranged below the four corner pillars 4 has a larger load area than the settlement reduction pile 2 arranged below the inner pillars 4 in simple calculation.
However, in the first place, the piled raft foundation structure 3 is a structure that allows the settlement of the settlement reduction pile 2 to some extent and directly expects the resistance of the ground on the bottom surface of the foundation 1. Therefore, even if the settlement reduction pile 2 arranged below the four corner pillars 4 bears five divided areas, the piled raft foundation structure having sufficient soundness can be realized as in the first to fourth embodiments. It was judged.

  Therefore, according to the piled raft foundation structure 3 of Example 5, the total number of pillars 4 of the small-scale structure (detached house) 50 is 16, whereas the settlement reduction pile of the piled raft foundation structure 3 The total number of 2 can be implemented with eight, and compared with the case where the settlement settlement piles are arranged under all the conventional pillars, the same support performance can be realized even if the total number of settlement settlement piles 2 is reduced by half. It can be said that it is reasonable, excellent in economic efficiency and workability.

  In the case of simple calculation, the area borne by one settlement-reducing pile 2 disposed on the outer periphery exceeds the area borne by the settlement-reducing pile 2 provided below the inner pillar 4 as in the fifth embodiment. As a precaution, one or a plurality of settlement reduction piles 2 may be added in a balanced manner.

FIG. 6 shows a different embodiment of a piled raft foundation for a small scale structure according to the present invention.
In the piled raft foundation structure 3 according to the sixth embodiment, the pillars 4 of the small-scale structure 60 are arranged at predetermined intervals (about 5 m in the illustrated example) vertically and horizontally as viewed from the plane direction. Based on the technical idea (see paragraphs [0024] to [0026]), the settlement reduction pile 2 (or the vicinity below the outer peripheral column 4 (the adjacent outer peripheral column 4 and the outer peripheral column 4) In order to increase the floor area shared by subsidence reduction piles 2 ′) arranged in the central part between the outer peripheral pillars 4 arranged in the outer peripheral part of the pillars 4, they are arranged in the side parts excluding the four corners. For the outer peripheral pillar 4 to be provided, by not arranging the settlement-reducing pile 2 at a position below at least one (two in the illustrated example) outer-circular pillar 4 for each side portion, the amount of the settlement-reducing pile 2 is not provided. The total number of subsidence reduction piles 2 (16 in the illustrated example) is greater than the total number of pillars 4 (24 in the illustrated example). It was set as the structure which supports the foundation 1 directly with a small quantity.
Note that the column design and pile design of the small-scale structure 60 are determined based on the same technical idea as in the first to fifth embodiments, and are therefore omitted (see paragraphs [0027] and [0028] above).

Therefore, the piled raft foundation structure 3 according to the sixth embodiment includes eight inner pillars 4, four corner pillars 4, and a part (a square shape) among the 24 pillars 4 provided in the small-scale structure 60 to be constructed. A total of 16 settlement reduction piles 2 are constructed at positions corresponding to the lower side (or the vicinity thereof) of the four side pillars 4 'at the site corresponding to the apex. Next, the foundation 1 is constructed directly on the pile head of the subsidence reduction pile 2 to form a piled raft foundation structure 3. Thereafter, the small-scale structure 50 having 24 pillars 4 on the direct foundation 1 is constructed.
Thus, according to the piled raft foundation structure 3 according to the sixth embodiment, the number of piles is 8 as compared with the piled raft foundation in which the settlement settlement piles are constructed directly through the foundations at the lower positions of all columns. This can be implemented with a reduced number of books.

Here, the floor area which one subsidence reduction pile 2 bears with respect to the floor area of the small-scale structure 60 is examined.
According to the first embodiment, the floor area of the small-scale structure 60 is divided into approximately 60 equal parts by an imaginary line (dashed line) crossing the center between the pillars 4 adjacent to each other vertically and horizontally. If the settlement reduction piles 2 are arranged under all the pillars 4 and implemented, the settlement reduction piles 2 arranged under the inner pillars 4 bear four divided areas, whereas the side pillars 4 The subsidence reduction pile 2 arranged below the lower part bears only two divided areas, and the subsidence reduction pile 2 provided below the four corner pillars 4 bears only one divided area.
Then, the settlement reduction pile 2 disposed below the side pillars 4 and the four corner pillars 4 has a supporting force equivalent to that of the settlement reduction pile 2 disposed below the inner pillar 4. Similarly, the settlement reduction pile 2 arranged below the side pillar 4 exhibits only a half supporting force, and the settlement reduction pile 2 arranged below the four corner pillars 4 supports 1/4. It means that only power is demonstrated.

Then, when it assumes that it implements with the structure which does not provide the settlement reduction pile 2 below the one part side pillar 4, ie, the structure of the said Example 6 (FIG. 6), it arrange | positions under the eight inner pillars 4. FIG. The settlement settlement piles 2 each bear four divided areas α, and the settlement settlement piles 2 provided below the four corner pillars 4 bear three division areas γ and are provided below the adjacent side pillars 4 ′. The settlement reduction pile 2 (or settlement settlement pile 2 ′ provided in the vicinity thereof) bears four divided areas β.
Then, the floor area borne by the settlement reduction pile 2 (2 ′) arranged below (or in the vicinity of) the four corner pillars 4 and the side pillars 4 ′ is arranged below the inner pillar 4 in simple calculation. Compared with the floor area borne by the settlement reduction pile 2, the piled raft foundation structure with sufficient soundness can be realized even if the number of the piles 2 is reduced.

  Therefore, according to the piled raft foundation structure 3 of Example 6, the total number of pillars 4 of the small-scale structure 60 is 24, whereas the total number of settlement reduction piles 2 of the piled raft foundation structure 3 is 16 It can be implemented with a book, and it can be said that equivalent support performance can be achieved even if the total number of settlement-reducing piles 2 is reduced by 8 compared to the case where the settlement-reducing piles are arranged under all pillars. It is economical and has excellent workability.

FIG. 7 shows a different embodiment of a piled raft foundation 3 for small-scale structures according to the present invention.
In the piled raft foundation structure 3 according to the seventh embodiment, the pillars 4 of the small-scale structure 70 are arranged at predetermined intervals (about 5 m) in the vertical and horizontal directions when viewed from the plane direction. Based on the idea (see paragraphs [0024] to [0026]), disposed on the outer periphery of the pillar 4 to increase the floor area shared by the settlement reduction pile 2 disposed below (or in the vicinity of) the outer pillar 4 Of the outer peripheral pillars 4 that are arranged, the outer peripheral pillars 4 that are arranged on the side edges excluding the four corners are set at a position below the outer peripheral pillars 4 at least one per side (two in the illustrated example). By not arranging 2, the total number of settlement settlement piles 2 (17 in the illustrated example) is less than the total number of columns 4 (25 in the illustrated example) by the amount that the settlement settlement pile 2 is not provided. 1 was supported.

Incidentally, the small-scale structure 70 according to the seventh embodiment is assumed to be an apartment, the building area is 20 m × 20 m, and the columns 4 are five rows each having four column spans in the beam-to-beam direction and the column direction. It is carried out with a total of 25 lines in 5 rows.
Note that the column design and pile design of the small-scale structure 70 are determined based on the same technical idea as in the first to sixth embodiments, and are therefore omitted (see paragraphs [0027] and [0028] above).

Therefore, the piled raft foundation structure 3 according to the seventh embodiment includes nine inner pillars 4 and four corner pillars 4 and a part (five) of the 25 pillars 4 provided in the small-scale structure 70 to be constructed. A total of 17 subsidence reduction piles 2 are mechanically constructed at positions corresponding to the lower side pillars 4. Next, the foundation 1 is constructed directly on the pile head of the subsidence reduction pile 2 to form a piled raft foundation structure 3. Thereafter, the small-scale structure 70 having 25 pillars 4 on the direct foundation 1 is constructed.
Thus, according to the piled raft foundation structure 3 according to the seventh embodiment, the number of piles is 8 as compared with the piled raft foundation in which the settlement subsidence piles are constructed directly through the foundations at the lower positions of all columns. This can be implemented with a reduced number of books.

Here, the floor area which one subsidence reduction pile 2 bears with respect to the floor area of the small-scale structure 70 is examined.
If the floor area of the small-scale structure 70 is divided into approximately 64 equal parts by a virtual line (dotted line) crossing the center between the pillars 4 adjacent to each other in the vertical and horizontal directions in accordance with the first embodiment, all the pillars are assumed. When the subsidence reduction pile 2 is arranged under 4 and carried out, the subsidence reduction pile 2 arranged below the inner pillar 4 bears four divided areas, whereas it is arranged below the side pillar 4. The subsidence reduction pile 2 which bears only two division areas, and the subsidence reduction pile 2 arrange | positioned under the four corner pillars 4 bears only one division area.
Then, since the settlement reduction pile 2 arranged below the side pillars 4 and the four corner pillars 4 has a supporting force equivalent to that of the settlement reduction pile 2 provided below the inner pillar 4, the same as in the first embodiment. In addition, the settlement reduction pile 2 disposed below the side pillar 4 exhibits only 1/2 support force, and the settlement reduction pile 2 disposed below the four corner pillars 4 exhibits 1/4 support force. However, it has only been demonstrated.

Therefore, when it is assumed that the subsidence reduction piles 2 are not provided below the side columns 4, that is, in the configuration of Example 7 (FIG. 7), the calculation of the nine inner columns 4 is simple. The subsidence reduction piles 2 arranged below each bear four divided areas α, and the subsidence reduction piles 2 arranged below the four corner pillars 4 bear three division areas γ, The settlement reduction pile 2 arranged below bears the four divided areas β.
Then, the floor area borne by the settlement reduction piles 2 disposed below the four corner pillars 4 and the side pillars 4 is, based on a simple calculation, the floor area borne by the settlement settlement piles 2 disposed below the inner pillars 4. Compared to the equivalent, the piled raft foundation structure with sufficient soundness can be realized even if the number of piles 2 is reduced.

  Therefore, according to the piled raft foundation structure 3 of Example 7, the total number of pillars 4 of the small-scale structure 70 is 25, whereas the total number of settlement reduction piles 2 of the piled raft foundation structure 3 is 17 It can be implemented with a book, and it can be said that equivalent support performance can be achieved even if the total number of settlement-reducing piles 2 is reduced by 8 compared to the case where the settlement-reducing piles are arranged under all pillars. It is economical and has excellent workability.

<Full-scale experiment according to Example 4 (FIG. 4)>
Based on the configuration of the above-described Example 4 (see FIG. 4), the present applicants have a conventional model foundation (see FIG. 8A) in which a total of 15 settlement-reducing piles 2 are arranged under all the pillars 4; The axial force borne by the settlement reduction pile 2 was measured by comparison with the model foundation (see FIG. 8B) of Example 4 in which the settlement reduction pile 2 is not disposed under some (six) side columns. FIG. 8C is a table showing the actual measurement results of the axial force, and FIG. 8D is a photograph showing a full-scale experimental situation.
The applicants have conducted a full-scale long-term measurement experiment for about 9 months at the Sakai Experiment Station in Kanto, and FIGS. 8A to 8D show the data “long-term measurement” created and measured by the applicants. A part of "Experiment Outline and Results" is transcribed as it is.

(Experiment overview)
Experiment contents: Load axial force long-term measurement of pile head load cell placed under full-scale model foundation Basic specification: 8m x 6m Solid foundation Slab thickness: 200mm, D13 @ 150mm (Vertical / Horizontal) Double reinforcement Foundation beam Beam Width: 200mm, beam reason: 400mm, D22-2 (both up and down)
Loading load: First stage 15 kN / m ² (total load 763 kN)
→ We assumed the weight of ordinary small-scale structures.
Second stage 21kN / m ² (total load 1068kN)
→ As a precaution, we assumed a weight approximately 1.4 times that of the normal small-scale structure.
Soil improvement: Ground improvement by piled raft foundation design Normal pile arrangement (conventional pile arrangement) 15 PR pile arrangement (present invention pile arrangement) 9 execution piles: Pile diameter φ200mm, pile length L8.0m, ultimate bearing capacity Ru84. 3kN burden load: Aiming for 50% pile body and 50% raft.
Allowable sinking amount: about 30mm as a guide.

(Summary of experimental background)
First, the first stage load (total load 763 kN) was supported for about 80 days by 15 piles (settlement reduction piles) (that is, the conventional model foundation (FIG. 8A) was implemented). Thereafter, the loading load was increased almost uniformly by 305 kN to support the second stage load (total load of 1068 kN) for about 80 days. After that, in one day work, the pile No. according to FIG. A total of six piles (subsidence reduction piles) of 2, 4, 6, 10, 12, and 14 were removed and used as the model foundation of Example 4 (FIG. 8B). This state was supported for about 80 days.
In order to obtain more reliable comparison data when measuring the load axial force, the present applicants consider the change in measurement axial force that is considered to be the effect of the water level, and during normal pile placement (conventional pile placement) Pile No. at the same water level as PR pile placement (present invention pile placement). Different mean values were compared.

(Experimental result)
According to the table of FIG. 8C, when the load axial force of each pile of the conventional model foundation of FIG. 8A and that of the model foundation of Example 4 of FIG. 8B is compared, the settlement reduction pile placed under the inner pillar whose sharing area does not change (Pile Nos. 5, 8, and 11) have almost no change (the median average value increased by 107%), and settlement settlement piles (pile Nos. 1, 3, 7, 9, 13, and 15) arranged on the outer periphery. ), It was confirmed that the load axial force increased by 120% on the outer periphery average value.
Although the load axial force of the model foundation of Example 4 is not equal, the reason is that there are complicated factors such as different load ratios flowing to the raft depending on the pile placement position (corner or center) in the shared area area. Conceivable.
However, from the actual measurement results, the conventional pile arrangement (see FIG. 8A) in a small-scale structure represented by a typical detached house so far has a small axial load on the outer peripheral portion, so that the total number of piles is useless. Although it was increased, it was confirmed that the load axial force can be made more uniform by the rationalized pile arrangement of the present invention in consideration of the shared area (see FIG. 8B).
That is, the settlement reduction pile (pile No. 1, 3, 7, 9, 13, and 15) provided below the outer peripheral column 4 according to the present invention pile arrangement is below the side column 4 according to the conventional pile arrangement. It is thought that the load which the provided subsidence reduction piles (pile No. 2, 4, 6, 10, 12, and 14) bear (almost equally) is shared.
Moreover, although the allowable value of the subsidence amount is usually about 30 mm as a guideline, according to the pile arrangement of the present invention (see FIG. 8B), a load as much as 1.4 times the assumed load (total load 1068 kN) is loaded. Nevertheless, it was confirmed that the amount of settlement was about 15 mm.

(Discussion)
From the above experimental results, regarding the variation arrangement of Example 4, the applicants have a total number of pillars 4 of the small-scale structure (detached house) 40 being 15, whereas the piled raft foundation structure 3 I was convinced that even if the total number of subsidence reduction piles 2 was nine, it could be implemented sufficiently. Moreover, it was convinced that the piled raft foundation structure 3 which maintained the soundness was fully realizable from the viewpoint of the whole structure (measured value of total pile head load, relationship between building load and total pile head load, etc.). By reducing the number of piles soundly, we were convinced that pile design (structural design) that maximizes the resistance of the ground directly on the bottom of the foundation could be realized.
Furthermore, in consideration of the fact that the amount of subsidence is about 15 mm in spite of having loaded a load that is 1.4 times the assumed load for Example 4, other implementations except Example 4 are taken into consideration. Also about Examples 1-7, the present applicants were convinced that the piled raft foundation structure 3 which maintained the soundness of the whole structure was fully realizable.

<Supplementary explanation>
The said Example 4, 6, and 7 differ from the said Examples 1-3, 5 and has arrange | positioned and implemented the subsidence reduction pile 2 also below the one part side pillar 4. FIG. Hereinafter, this significance will be described.
When the present applicants conducted various simulation analyzes of the settlement reduction pile 2 provided below the number of pillars and the pillar arrangement of a small-scale structure that could be constructed, the present invention found that Judgment that the settlement subsidence pile 2 below the pillar 4 is the most rational for realizing a sound piled raft foundation structure 3 and that it is possible to simplify pile design and pile construction. did.
On the other hand, as the floor area of a small-scale structure increases, that is, the dimension in the beam-to-beam direction or the cross-beam direction, the soundness of the piled raft foundation structure 3 is reduced with respect to the side pillars 4 continuously provided in these directions. In order to realize, it was found that it is necessary to arrange the settlement reduction pile 4 below the one side column 4 among the three side columns 4. In other words, it has been found that when three or more side pillars 4 are arranged in the beam-to-beam direction or the column direction, it is necessary to arrange the settlement reduction piles 2 below at least one side pillar.
Therefore, when there are three or more side pillars 4 that are continuous in the beam-to-beam direction or the row direction, the side pillars are appropriately arranged so that the three side pillars 4 where the settlement reduction piles 2 are not arranged are not continued. The subsidence reduction piles 2 are arranged below 4.

Expressing the above consideration with a simple formula,
Number of divided areas> number of inner pillars × number of areas to be shared (ie, 4) + number of four corner pillars (ie, 4) × number of areas that can be shared (usually 4, 5 considering allowance for settlement)
It becomes.
When this condition is satisfied, it can be determined that it is preferable to dispose the settlement reduction piles 2 on a part of the side pillars 4 as an approximate guide.
For example, in the case of Example 1 and Example 2 (see FIGS. 1 and 2), the left side is 16 pieces. The right side is 1 × 4 + 4 × 4 = 20. That is, in this case, since the quantity on the right side is large and the above formula is not satisfied, it can be determined that the soundness of the piled raft foundation structure is maintained even if the settlement reduction pile is not arranged under the side column.
Next, in the case of the said Example 3 (refer FIG. 3), the left side is 24 pieces. The right side is 2 × 4 + 4 × 4 = 24. That is, in this case as well, since the left side and the right side are the same number and do not satisfy the above formula, it can be determined that the soundness of the piled raft foundation structure is maintained even if the settlement reduction pile is not arranged under the side column.
Similarly, in the case of the said Example 4 (refer FIG. 4), the left side is 32 pieces. The right side is 3 × 4 + 4 × 4 = 28. That is, in this case, the above formula is satisfied. Therefore, in terms of simple calculation, it can be determined that if one or two (see FIG. 4) side settlement pillars are placed under the side pillars, the pile raft foundation structure is more sound when considering the balance. However, if the number of areas that can be shared by the four corner pillars is 5, the left side and the right side will be the same number (32), so depending on the ground properties, it is possible to implement without placing subsidence reduction piles on the side pillars. It can be judged.

Similarly, in the case of the said Example 5 (refer FIG. 5), the left side is 36 pieces. The right side is 4 × 4 + 4 × 4 = 32. That is, in this case, the above formula is satisfied. However, in Example 5, assuming that the number of areas that can be shared by the four corner pillars is 5, the left side and the right side are the same number (36), so a structure in which no settlement reduction piles are arranged on the side pillars was selected.
Similarly, in the case of Example 6 (see FIG. 6), the left side is 60 pieces. The right side is 8 × 4 + 4 × 4 = 48. That is, in this case, the above formula is satisfied. Therefore, in terms of simple calculation, considering the balance, it can be determined that placing the settlement subsidence piles under the four side pillars (see FIG. 6) maintains the soundness of the piled raft foundation structure. In this case, even if the number of areas that can be shared by the four corner pillars is five, the right side is 52 and less than the left side (60). You can see that the basic structure should be built.
Similarly, in the case of Example 7 (see FIG. 7), the left side is 64 pieces. The right side is 9 × 4 + 4 × 4 = 52. That is, in this case, the above formula is satisfied. Therefore, it can be judged that the soundness of the piled raft foundation structure is maintained by arranging three settlement reduction piles under the side pillars in consideration of balance or four (see FIG. 7) in simple calculation. In this case, even if the number of areas that can be shared by the four corner pillars is five, the right side is 56 and less than the left side (64). You can see that the basic structure should be built.

As described above, the first to seventh embodiments have been described with reference to the drawings. However, the present invention is not limited to the illustrated examples, and variations of design changes and application that are usually performed by those skilled in the art within the scope not departing from the technical idea thereof. Note that it includes the range.
For example, the small-scale structure 10 according to the present embodiment has been described centering on a structure whose outer shape is rectangular in plan view and whose columns are regularly arranged vertically and horizontally, but is not limited thereto.

1 direct foundation (solid foundation)
2 Subsidence reduction pile 3 Piled raft foundation structure 4 Pillar 10, 20, 30, 40, 50, 60, 70 Small structure

Claims (8)

A piled raft foundation structure for a small-scale structure having a structure in which the weight of the small-scale structure is directly borne by the foundation and a plurality of settlement reduction piles,
Each of the plurality of settlement reduction piles has an equivalent supporting force,
The plurality of settlement reduction piles are arranged in an outer peripheral part of the small-scale structure and an inner part inside the outer peripheral part,
Compared with the case where one subsidence reduction pile is arranged under each pillar of the small-scale structure, the number of subsidence reduction piles arranged on the outer peripheral part is reduced, and the subsidence reduction piles are arranged on the outer peripheral part of the small-scale structure. the floor space subsidence reduction piles share, said by subsidence reduced pile placed inside portion to expand so as to approach the floor area to be shared, one by one subsidence reduced pile under each pillar of the small structure characterized by being configured to support the spread foundation with settlement reducing piles of smaller quantities than the case of disposing, piled raft foundation structure for small-scale structures. A piled raft foundation structure for a small-scale structure having a structure in which the weight of the small-scale structure is directly borne by the foundation and a plurality of settlement reduction piles,
Each of the plurality of settlement reduction piles has an equivalent supporting force,
The pillars of small structures, and the outer columns disposed in the outer peripheral portion is divided into an inner pillar other than the outer peripheral pole, if the ratio of the arranged one by one subsidence reduced pile under each pillar of small structures The subsidence reduction pile is arranged under or near one outer peripheral column, and arranged in the outer peripheral part in a configuration in which no other subsidence pile is arranged in the other outer peripheral column adjacent to the one outer peripheral column. the floor space subsidence reduced pile to place the outer peripheral portion of the small-scale structure by reducing the number of reduction piles are shared, subsidence reduction piles placed under said pillars to expand so as to approach the floor area to share it is characterized in that it has a structure for supporting the spread foundation with settlement reducing piles of smaller quantities than the case of disposing one by one subsidence reduced pile under each pillar of the small structure, small structures Piled raft foundation structure for goods. A piled raft foundation structure for a small-scale structure having a structure in which the weight of the small-scale structure is directly borne by the foundation and a plurality of settlement reduction piles,
Each of the plurality of settlement reduction piles has an equivalent supporting force,
The pillars of the small-scale structure are arranged at predetermined intervals in the vertical and horizontal directions when viewed from the plane direction.
Divide the floor area of a small-scale structure into multiple divided areas of almost the same shape and size with virtual lines crossing the center between columns that are adjacent vertically and horizontally, and one subsidence reduction pile under each column Assuming that
The pillars of small structures, and the outer columns disposed in the outer peripheral portion is divided into an inner pillar other than the outer peripheral pole, one of four divided areas around the one of the inner pillars under the inner pillar as a reference to subsidence reduced piles sharing, the floor area of a single settlement reducing pile beneath or near the one outer peripheral pillars are shared, the other outer peripheral columns adjacent to the one outer peripheral pillars of By reducing the number of settlement-reducing piles placed on the outer periphery in a configuration without placing settlement-reducing piles, the floor area corresponding to the four divided areas shared by one settlement-reducing pile under the inner pillar is expanded. be to, characterized in that a structure for supporting the spread foundation with settlement reducing piles of smaller quantities than the case of disposing one by one subsidence reduced pile under each pillar of the small structure, small Piled raft foundation for structures. A piled raft foundation structure for a small-scale structure having a structure in which the weight of the small-scale structure is directly borne by the foundation and a plurality of settlement reduction piles,
Each of the plurality of settlement reduction piles has an equivalent supporting force,
The pillars of the small-scale structure are arranged at predetermined intervals in the vertical and horizontal directions when viewed from the plane direction.
Assuming that one subsidence-reducing pile is placed under each pillar of the small-scale structure, it is placed on the four side edges excluding the four corners among the outer-circular pillars placed on the outer circumference of the small-scale structure. For the outer peripheral column, by reducing the number of subsidence reduction piles arranged in the outer peripheral part in a configuration in which no subsidence reduction piles are arranged under at least one outer peripheral column with respect to one side part, by subsidence reduced pile arranged in the vicinity thereof to enlarge the floor area to be shared, the direct sinking reduce pile quantities less than if the arranging one by one subsidence reduced pile under each pillar of small structures A piled raft foundation for small-scale structures, characterized in that it is configured to support the foundation.   5. The small portion according to claim 2, wherein the vicinity of the outer peripheral column on which the settlement reduction pile is disposed is a central portion between the adjacent outer peripheral column and the outer peripheral column. Piled raft foundation for large scale structures.   The piled raft foundation structure for a small-scale structure according to any one of claims 2 to 4, wherein the outer peripheral column on which the settlement reduction pile is disposed is a four-corner column.   The piled raft foundation structure for a small-scale structure according to any one of claims 1 to 6, wherein each of the subsidence reduction piles has substantially the same pile diameter and pile length.   The piled raft foundation structure for a small-scale structure according to any one of claims 1 to 7, wherein the small-scale structure is a unit type detached house.

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