JP4961604B2 - Pile foundation structure and pile head treatment method - Google Patents

Description

  The present invention relates to a pile foundation structure without a foundation beam used for a structure such as a building, and a pile head processing method applied to the pile foundation structure, and a building, factory, garage, and warehouse straddling a track and a platform. It is applied to pile foundations such as buildings such as buildings, steel towers and buildings on slopes.

  For example, a building that straddles a railroad station track and a platform (hereinafter referred to as a building above the railroad) has a structure in which there is no underground beam extending in the horizontal direction at the foundation. Conventionally, the basic structure of such a building is generally embedded in a single cast-in-place concrete pile with one steel column, or the steel column base is wound with concrete through footing or exposed fixed column base. (Hereinafter referred to as one pillar-one pile structure).

  However, in the construction work on the building over the railway, the working space is restricted and the working time is limited to nighttime, so it is required to shorten the working time and construction man-hours. Reduction is also required.

  As prior art documents related to the present invention, there are, for example, Patent Documents 1 and 2. As shown in FIG. 10, these are semi-fixed direct foundation structures composed of unreinforced concrete 116 that can expect only its own weight and compression resistance against the stress transmitted from the steel column 122 that supports the load of the building. It is arranged in the root cutting part 117 excavated.

JP 2002-146800 A JP 2002-121747 A

  When cast-in-place concrete piles are used as in the past, plant facilities that circulate large-scale mud water are necessary, and there is a risk that adjacent tracks will be deformed by excavation. In addition, industrial waste such as muddy water and excavated soil is also generated.

  In addition, when the foundation structure of the building above the track is a one-column / one-pile structure, since the bending moment, shearing force and axial force received by the column are directly borne on the pile, the one-column / one-pile structure when the pile yields There is a risk that buildings over the tracks supported by will collapse.

  In addition, since a large bending moment is transmitted from a pillar to a pile with one pillar and one pile structure, a large pile diameter (for example, 1800 mm or more) is set to increase bending rigidity to support the building above the railway. Therefore, the foundation structure may be enlarged.

  On the other hand, in the semi-fixed direct foundation structure described in Patent Document 1, as shown in FIG. 10, the bending moment received by the steel column 122 is transmitted to the first foundation steel beam 126, and further the PHC pile 124 via the support metal 125. However, since the joint between the PHC pile 124 and the first foundation steel beam 126 cannot resist the tensile force, if the bending moment received by the steel column 122 increases to some extent, it acts on one PHC pile 124. It becomes impossible to resist the pulling force and a lift occurs. Therefore, in order to suppress the lifting, it is necessary to place the unreinforced concrete 116 in the root cutting portion 117 integrally with the support devices 125, 125.

  In addition, this method has a problem that the residual soil discharged when the root cutting part 117 is excavated becomes industrial waste as it is.

  In order to solve the above-described problems, the present invention provides a plurality of horizontal beams which are joined to a column base of a steel column supporting a structure such as a building and extend horizontally from the column base in the radial direction, and tip portions of the horizontal beams. A pile foundation structure without foundation beams, characterized in that the pile foundation structure is composed of a plurality of piles having a pull-out resistance mechanism by protrusions, which are tightly coupled to each other and extending downward. That is, the present invention transmits bending moment, shearing force and axial force acting on a steel column to a plurality of piles having a pull-out resistance mechanism via a plurality of horizontal beams arranged radially from the column base of the column. To do.

  The number of the horizontal beams is three or more, and it is preferable that the piles having the pull-out resistance mechanism are fastened to all the horizontal beam front ends.

  It is preferable that the horizontal line connecting the column base of the steel column and the core of the pile having the pull-out resistance mechanism is arranged so that the member axis of the horizontal beam coincides.

  The adjacent tips of the plurality of horizontal beams are preferably connected by a stiffening beam.

  It is preferable that a top plate is horizontally attached to the head of the pile by welding or the like, and the tip of the horizontal beam is joined to the top plate by welding or bolts.

  In the pile foundation structure of the present invention, in the cutting process of the steel pipe pile head after burial, the temporary support hardware is fixed inside the steel pipe near the pile head and is supported by the support hardware so that the cutting machine travels to the top of the pile head. It is preferable to cut the steel pipe pile head by holding the plate horizontally and running the cutting machine along a guide rail provided on the cutting machine running plate.

  Further, in the pile foundation structure of the present invention, in the installation of the adjustment part for connecting the horizontal beam and the steel pipe pile head, the adjustment part is supported by a temporary support hardware fixed inside the steel pipe near the pile head. It is preferable that the adjustment plate and the steel pipe pile head are welded to each other by holding a top plate attached in advance horizontally and providing a guide rail on the top plate to run the welding machine.

  According to the present invention, bending moment, shearing force and axial force acting on a steel column are transmitted from a column base of the column to a plurality of piles having a pulling resistance mechanism via a plurality of horizontal beams arranged in a radial direction. Therefore, there are the following effects.

(1) In the case of the conventional one-column / one-pile structure, the bending moment, which is a heavy load, is converted into axial force and transmitted to the pile in the present invention, so that the bending moment to the pile can be reduced and the pile diameter can be reduced. Can be thin.
(2) Since a pile having a pull-out resistance mechanism is used, this acts as an anchor, can resist a pulling force up to a certain amount, and can resist a large bending moment. It is possible to eliminate the unreinforced concrete at the root cutting portion for suppressing the conventional lifting.
(3) If a steel pipe pile with a blade that rotates and penetrates is used as a pile having a pulling resistance mechanism, industrial waste such as muddy water and discharged residual soil can be greatly reduced as compared with a conventional cast-in-place concrete pile.
(4) A pile that rotates and penetrates is beneficial for environmental measures because it has less noise and vibration.
(5) Since there is no excavation for cast-in-place concrete piles, the risk of deformation of adjacent tracks is greatly reduced.

(6) Since the root cutting is backfilled after the foundation structure of the present invention is constructed, the amount of off-site disposal of the root cutting can be greatly reduced.
(7) Large-scale mud circulation plant facilities are not required.
(8) Since the work period of the field work can be shortened, the present invention is extremely useful as the basic structure of the building over the railway with severe time constraints.
(9) Cost reduction can be expected while maintaining the strength of the foundation structure equal to or higher than the conventional one-column / one-pile structure.
(10) In the present invention, since the foundation structure is self-supporting, the stay required in the conventional one-column / one-pile structure is not required, and labor saving is achieved in the steel frame construction.

  Examples of the present invention are shown below.

  FIG. 1 is a perspective view for explaining the configuration of the first embodiment of the present invention. A plurality of horizontal beams 2, 2... Are joined to the column base 1a of the steel column 1 supporting the building so as to extend horizontally from the column base 1a in the radial direction. The pile heads of the steel pipe piles 3 are fastened to the lower surfaces of the material end portions of the horizontal beams 2, 2. When a winged steel pipe pile is used as a pile having a pulling resistance mechanism, the steel pipe pile 3 extending vertically downward is normally composed of an upper steel pipe 34a, a middle steel pipe 34b, and a lower steel pipe 34c as shown in FIG. At the lowermost end of 34c, a propulsion blade 61 and an excavation claw 62 for rotating and inserting the steel pipe pile 3 are provided. Since the length of the steel pipe pile 3 varies depending on the depth of the support layer of the ground, the length of the steel pipe pile 3 may be sufficient if only the lower steel pipe 34c is used. The upper steel pipe 34a, middle steel pipe 34b, and lower steel pipe 34c are joined to each other by on-site welding and mechanical joints such as screws and couplers.

  Thus, since the steel pipe pile 3 provided with the propulsion blade 61 and the excavation claw 62 is rotated and penetrated, the discharged residual soil accompanying the pile construction is greatly reduced, and noise and vibration are also small, which is beneficial for environmental measures.

  1, 4 and 4 are stiffening beams that connect the ends of adjacent horizontal beams 2, 2,..., And are joined to the horizontal beams 2, 2,.

  The top plate 37 is attached to the steel pipe pile 3 by first cutting the tops of the plurality of steel pipe piles 3, 3,. After adjusting the height and level of 37, 37..., The welding is performed on-site to the tops of the steel pipe piles 3, 3.

  As shown in FIG. 3, the top plate 37 is attached to the steel pipe pile 3 by performing fillet welding 20 on the site with a plurality of ribs 38, 38. It is relatively easy. In this case, since the ribs 38, 38... Directly transmit the total stress from the upper part to the steel pipe pile 3, the rib 38 and the fillet weld 20 need to be sufficiently sized to transmit the total stress.

  Although the above-mentioned method by fillet welding is easy, since a human usually performs welding work, a work space of a certain level or more is required. In the foundation construction of the building over the railway, which is the main object of the present invention, since the root cutting must be minimized, it may not be possible to secure a space necessary for a person to work. In such a case, robot welding as shown in FIGS. 4 to 6 is effective.

  FIG. 4 is an explanatory view showing a method of cutting the steel pipe pile head after embedding, and FIG. 5 shows a view D in FIG. In the cutting process of the pile head after embedding, first, the disk-shaped support metal 32 is suspended so as to be substantially horizontal by using bolts 33a, 33a..., Nuts 33b, 33b. . At this time, the centers of the receiving hardware 31 and the supporting hardware 32 are set to be in a combined state. Then, the support hardware 32 is inserted into the steel pipe 34, and the receiving hardware 31 is temporarily placed on the upper end of the steel pipe 34.

  The diameter of the support metal 32 and the inner diameter of the steel pipe 34 are substantially the same, and the support metal 32 is fixed by fillet welding in a balanced manner at four or more locations in the circumferential direction of the inner peripheral surface of the steel pipe 34.

  Next, in order not to damage the fore end of the steel pipe 34, a cross-shaped position fixing metal 35 is stacked on the upper surface of the receiving metal 31 with bolts 33a, 33a penetrating the nuts 33b, 33b ... directly below the receiving metal 31. After securing the height and level of the receiving metal 31, it is temporarily attached to the contact portion between each arm 35 a, 35 a... Extending downward from the end of the position fixing metal 35 and the outer peripheral surface of the steel pipe 34. It welds and the position of the receiving metal 31 is fixed.

  Next, as shown in FIG. 4, a disk-shaped cutting machine traveling plate 36 having a diameter larger than the outer diameter of the steel pipe 34 is provided on the upper surface of the position fixing metal 35 with bolts 33a, 33a, and nuts 33b, 33b. Install with…. Therefore, since the cutting machine travel plate 36 is supported by the support hardware 32 via the bolts 33a, 33a, etc., the steel pipe 34 is not burdened.

  A guide rail 51a extending in the circumferential direction is provided at the edge of the cutting machine travel plate 36, and the nozzle driving device 51b travels along the guide rail 51a. The nozzle driving device 51b is provided with an arm 51c having a plurality of rotation driving units, and a cutting gas is discharged from an opening (not shown) formed at the tip of the nozzle 51d. Yes.

  The nozzle driving device 51b incorporates a control circuit (not shown) that generates control signals for executing operations related to cutting, such as the traveling speed of the nozzle driving device 51b and the rotation angle of the arm 51c.

  In cutting the steel pipe pile head, the tip of the nozzle 51d is positioned on the planned cutting portion 41 (member length 350 mm or more) of the steel pipe 34 indicated by a broken line, and the nozzle 51d is moved along the guide rail 51a while running the nozzle driving device 51b. Is driven, gas is released from the tip of the nozzle 51d, and the steel pipe 34 is automatically cut. After the cutting is completed, the cutting machine set and the cutting machine traveling plate 36 are removed, and the position fixing metal 35, the receiving metal 31, the bolts 33a, 33a, and the nuts 33b, 33b are removed together with the upper steel pipe 34a of the cut steel pipe 34. . In addition, the cut | disconnected upper steel pipe 34a is utilized as a part of below-mentioned adjustment part.

  The cut surface of the steel pipe 34 after cutting, that is, the middle steel pipe 34b, is finished by removing the mill scale using a grinder or the like so that scratches and dust do not adhere.

  An adjustment section (described later) that connects the horizontal beam 2 and the middle steel pipe 34b is welded and fixed to the middle steel pipe 34b. A method for manufacturing and attaching the adjusting portion will be described with reference to FIG.

  Check the direction of the pillar core of the steel column 1 and the pile core of the pile 3 (including the flat state of the major and minor diameters of the steel pipe cross section), and the upper steel pipe 34a (member length 350 mm or more) cut on site as a steel pipe for the adjustment part Prepare using. Next, based on the actual measurement data (column core, pile core, horizontal beam axis core and bolt core direction) obtained in the field measurement, the top plate with the bolt hole 71a for the high strength bolt 71 in the upper steel pipe 34a. 37 and ribs 38, 38... Are assembled at the factory by welding.

  The adjustment part thus manufactured and the middle steel pipe 34b are connected as follows. A guide rail 61a extending in the circumferential direction of the top plate 37 is provided at the edge of the top plate 37, and the torch drive device 61b travels along the guide rail 61a.

  The torch driving device 61b is provided with an arm 61c having a plurality of rotation driving portions, and a welding torch 61d is provided at the tip of the arm 61c.

  The torch drive device 61b generates a control signal for performing operations related to welding with respect to the traveling speed of the torch drive device 61b, the rotation angle and groove angle of the arm 61c, the root gap, and the like (not shown). A control circuit is incorporated.

  Then, the backing metal 51 provided at the lower end of the adjusting portion is abutted against the upper surface of the support metal 32 welded to the inner peripheral surface of the middle steel pipe 34b, and after positioning the upper steel pipe 34a, the inside of the groove of the steel pipe Are fixed by assembly welding, the torch drive device 61b is driven, and the upper steel pipe 34a and the middle steel pipe 34b are connected by automatic welding.

  Next, the configuration of the horizontal beam 2 will be described in detail with reference to FIG. FIG. 7 is a plan view and a cross-sectional view of the foundation structure of the first embodiment. The steel column 1 is a square steel pipe, the horizontal beam 2 is an H-shaped steel, and the column base 1a of the steel column 1 and the horizontal beam 2 are joined to each other by connecting the web 2a of the horizontal beam 2 to the skin plate on the side surface of the steel column 1. The flange 2b of the horizontal beam 2 is welded to the diaphragm of the steel column 1 respectively. Of course, the steel column 1 may be a circular steel pipe or the like, and the horizontal beam 2 and the stiffening beam 4 may be a box-shaped cross-section member or the like.

  In the case of the first embodiment, the cores 94, 94 of the steel column 1 and the member axial cores 96 of the horizontal beams 2, 2,.

  At the position where the steel pipe pile 3 is joined at the front end side of the horizontal beam 2, ribs 2c are provided as reinforcing materials on both the left and right sides of the web 2a of the horizontal beam 2. The steel pipe pile 3 is bolted to the lower flange of the horizontal beam 2 via a top plate 37 integrated with the steel pipe pile 3. The bolts use high strength bolts 71, 71... And nuts 72, 72.

  The steel pipe pile 3 is rotationally inserted into the bottom surface of the concave root cutting part 5 formed on the ground. The top portion of the steel pipe pile 3 immediately after the completion of penetration is in a state of protruding from the bottom surface of the root cutting portion 5 so that a predetermined height can be secured.

  Since the excavated soil at the time of root cutting and the discharged residual soil at the time of rotation penetration of the steel pipe pile 3 are backfilled in the root cutting part 5, the discharged residual soil of the root cutting part 117 of Patent Documents 1 and 2 becomes industrial waste as it is. In comparison, it is clear that the present invention can greatly contribute to the reduction of industrial waste.

  Here, the column base 1a, the horizontal beams 2, 2,... And the reinforcing beams 4, 4,... Are buried in the backfill soil in the concave root cutting portion 5, and therefore, a corrosion prevention paint is applied as a rust prevention treatment. Prevents contact with the soil.

  Since this invention is the above structures, when external force, such as an earthquake, acts on a building structure, it will become the following stress transmission mechanisms.

  When an external force such as an earthquake acts on the steel column 1 to generate an axial force, a bending moment and a shearing force, the axial force and bending moment of the steel column 1 become the bending moment of the horizontal beam 2 and the shearing force becomes the bending force of the horizontal beam 2. It is transmitted as an axial force. Further, the bending moment of the horizontal beam 2 is transmitted to the steel pipe pile 3 through the top plate 37 connected to the lower surface of the tip of the horizontal beam 2 as a couple divided by the distance L between the pile cores shown in FIG. Then, it becomes a compression axial force or a tensile axial force and is transmitted from the steel pipe pile 3 to the ground. Further, the axial force of the horizontal beam 2 becomes a shearing force of the steel pipe pile 3 and is transmitted to the ground. In addition, although it is usual to design so that a tensile axial force may not arise as much as possible with a normal pile, the steel pipe pile 3 used for this invention has a drawing-out resistance mechanism, such as having a wing 61 at the lower end. Since it plays the role of an anchor and can resist a pulling force up to a certain amount, it can also resist a large bending moment.

  Thus, the foundation structure according to the present invention converts the bending moment generated in the steel column 1 into a couple and transmits it to the steel pipe pile 3 as an axial force. Therefore, since the bending moment which the steel pipe pile 3 receives can be reduced, a diameter can be made smaller than the pile of the conventional 1 pillar-1 pile structure, and a foundation structure can be made compact. Moreover, in the 1 pillar-1 pile structure, it is necessary to build the frame while supporting 3 to 4 columns and beams at the same time using a stay at the time of building the upper frame. Since it is self-supporting, there is no need for stays, and labor can be saved in the construction of steel frames, shortening the construction period and reducing construction costs.

  In the first embodiment, since the horizontal beams 2, 2,... Are connected by the reinforcing beams 4, 4,..., The rigidity of the horizontal beams 2, 2,. Since all the steel pipe piles 3, 3 ... behave integrally, a strong foundation structure can be formed.

  Example 2 will be described with reference to FIG. In the first embodiment, the cores 94, 94 of the steel column 1 and the member shaft cores 96 of the horizontal beams 2, 2,... Match, but the second embodiment is a case where they do not match. FIG. 8 is a plan view of the second embodiment. Due to construction errors, the pile cores 95, 95... Of the steel pipe piles 3, 3,. The state which made the member axial core 96 of the horizontal beams 2, 2, ... match with the line which connects the core 91 and the pile cores 95, 95 ... is shown. In this way, in a state where the pile core 95 is eccentric from the column core 94, a small torsional moment may be generated in the horizontal beams 2, 2... By the transmission stress from the steel column 1. Since the horizontal beams 2, 2 ... are connected to each other, the torsional moment can be suppressed, and a strong foundation structure can be provided.

  In the construction in the second embodiment, the positions of the pile cores 95, 95... Eccentric from the cores 94, 94 of the steel column 1 are actually measured, and the members are connected to the lines connecting the column core 91 and the pile cores 95, 95. The horizontal beams 2, 2... Are manufactured so that the shaft cores 96 coincide.

  In the above two embodiments, one steel column is supported by four piles, but if there are three or more piles, the foundation structure of the present invention is established. Further, the joint between the pile head and the horizontal beam may be a fixed joint, a pin joint, or a semi-rigid joint.

  The foundation structure according to the present invention can also be applied to structures other than buildings above the railway track, such as factories, garages, and warehouses.

  The analysis method of the whole structure supported by the pile foundation structure of this invention is demonstrated with reference to FIG. FIG. 9 is a flowchart showing the structure analysis procedure. In the structural analysis, proceed according to the following procedures in accordance with “Structure Standards for Buildings Over the Track (Low-rise) Structural Design 2002 (Railway Technical Research Institute)”.

(S101) From the ground information (N value, shear strength, etc.), the ground horizontal and vertical spring constants, the supporting force of the steel pipe pile 3 and the pulling strength are calculated.
(S102) Using the structural calculation program compliant with the above-mentioned “Building design over the railway (low-rise) structure design standard 2002”, for the analytical model, the steel column 1 and other members of the superstructure, horizontal beam 2, stiffening beam 4. Sectional performance (cross-sectional area, secondary moment of section, section modulus, etc.) is calculated for steel pipe pile 3, and virtual springs arranged at each node divided in the length direction of steel pipe pile 3 are calculated by (S101). The ground horizontal and vertical spring constants are input to the steel pipe pile 3 and the supporting force and pulling strength are input.
(S103) The above structural calculation program is executed, and the superstructure including the steel column 1, the horizontal beam 2, the stiffening beam 4, and the steel pipe pile 3 are continuously integrated, and the structural analysis is performed by the finite element method.

  Based on the analysis results obtained as described above, various structural provisions, retained horizontal proof stress, deformation performance, and the like are confirmed in accordance with the above-mentioned “Building design over skyline (low-rise) structure design standard 2002”. (Details omitted)

It is a perspective view of the pile foundation structure of Example 1 of the present invention. It is a side view which shows the general view of the steel pipe pile used by this invention. An example of the pile top plate used by this invention is shown, (a) is a vertical sectional view, (b) is a horizontal sectional view. The automatic cutting method of the pile head of this invention is shown, (a) is a top view, (b) is a vertical sectional view. FIG. 5 is a cross-sectional view taken along the line D in FIG. 4. It is a vertical sectional view which shows the adjustment part automatic welding method to the pile head of this invention. (A) of the pile foundation structure of Example 1 is a top view, (b), (c) is a vertical sectional view. It is a top view which shows the pile foundation structure of Example 2 of this invention. It is the flowchart which showed the structure analysis procedure of this invention. It is a vertical sectional view showing a semi-fixed direct foundation structure of a conventional example.

Explanation of symbols

1: Steel column 1a: Column base 2: Horizontal beam 2a: Web 2b: Flange 2c: Rib 3: Steel pipe pile 4: Stiffening beam 5: Root cut part 20: Fillet weld 31: Receiving metal 32: Supporting metal 33a: Bolt 33b: Nut 34: Steel pipe 34a: Upper steel pipe 34b: Medium steel pipe 34c: Lower steel pipe 35: Position fixing hardware 35a: Arm part 36: Cutting machine travel plate 37: Top plate 41: Planned cutting part 51: Backing metal 51a: Guide rail 51b: Nozzle drive device 51c: Arm 51d: Nozzle 61: Propeller blade 61a: Guide rail 61b: Torch drive device 61c: Arm 61d: Torch 62: Excavation claw 71: High strength bolt 71a: Bolt hole 72: Nut 91: Column core 94: Street core 95: Pile core 96: Horizontal beam member core L: Distance between pile cores 116: Unreinforced concrete 117: Root cutting part 122: Steel column 124: PHC pile 125: Support device 126: First foundation steel frame

Claims (7)

Connected to the column base of a steel column that supports the structure, and has a plurality of horizontal beams that extend radially from the column base in a radial direction, and a pull-out resistance mechanism with protrusions that is tightly connected to the tip of these horizontal beams and extends downward It is composed of a plurality of piles, and a bending moment, shearing force and axial force acting on the steel column are provided via a plurality of horizontal beams arranged radially from the column base of the steel column. A pile foundation structure without foundation beams, which is transmitted to a plurality of piles .
  The pile foundation structure without a foundation beam according to claim 1, wherein the number of the horizontal beams is three or more, and piles having the pulling-out resistance mechanism are tightly connected to the tip portions of all the horizontal beams.   The horizontal line connecting the column base of the steel column and the core of the pile having the pull-out resistance mechanism is arranged so that the member axis of the horizontal beam coincides. Item 3. The pile foundation structure according to any one of items 2 to 3.   The pile foundation structure according to any one of claims 1 to 3, wherein adjacent ends of the plurality of horizontal beams are connected by a stiffening beam.   The top plate is horizontally attached to the head of the pile, and the tip of the horizontal beam is joined to the top plate by welding or bolts. Pile foundation structure as described in   In the cutting process of the steel pipe pile head after burial, the temporary support hardware is fixed inside the steel pipe near the pile head, and supported by the support hardware, the cutting machine traveling plate is held horizontally at the top of the pile head, A pile head treatment method for a steel pipe pile, wherein the head of the steel pipe pile is cut by running the cutting machine along a guide rail provided on the cutting machine travel plate.   In the installation of the adjustment part to connect the horizontal beam and the steel pipe pile head, the top plate pre-attached to the adjustment part is held horizontally by supporting it with a temporary support hardware fixed inside the steel pipe near the pile head. And a steel pipe pile head treatment method characterized by welding the adjustment part and the steel pipe pile head by providing a guide rail on the top plate and running the welding machine.

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