Method for constructing bundle foundation pile structure

Abstract

To ensure a sufficient interval between adjacent prefabricated piles to ensure a larger bearing capacity according to large diameter pile holes.SOLUTION: A structure of pile hole 40 and vertically connected prefabricated piles 10A... is determined in advance based on required bearing capacity, etc., and imaginary division line 15a... is set in the pile hole 40 to form four pile holding sections 17A.... The pile hole 40 is excavated with a pile hole excavation rod 1 (a) (b), and the pile hole excavation rod 1 is pulled up. A pile insertion rod 20 forming the four pile holding sections 17A... is inserted into the pile hole 40 (d). Prefabricated piles 9 are lowered while connecting them into the first pile holding section 17A to form the vertically connected prefabricated piles 10A (e). Similarly, vertically connected prefabricated piles 10B... are installed in each pile holding section 17B... (f) (g). The pile insertion rod 20 is returned to the ground 38 and filled with cement milk (g). Horizontal load-bearing members 30 are inserted into a cement milk layer 44 to form a bundled pile foundation structure 50 (i).SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] This invention relates to a method for constructing a bundled foundation pile structure in which vertically connected precast piles, which are precast piles connected vertically, are buried in pile retaining sections that divide a pile hole into multiple sections when viewed in a plane. [Background technology]

[0002] Many construction methods have been proposed in which multiple prefabricated piles are erected in one pile hole with gaps between them, and the gaps are filled with cement milk or the like (Patent Documents 1 to 3). In Patent Document 1, the outer diameter of the precast piles was assumed to be about 300 mm, and the precast piles were installed with a distance between them. In particular, there was no effort to maintain the distance between each precast pile. In addition, Patent Document 2 proposes, for example, an example in which 12 prefabricated concrete piles with a diameter of 300 mm or 5 prefabricated piles with a diameter of 900 mm are buried in a pile hole with a diameter of 3000 mm, and the required number of prefabricated piles are bundled with a spacer at the heads to maintain a predetermined distance. Also, in order to bury the bundled prefabricated piles together in a pile hole filled with cement milk, a buoyancy adjustment device is provided at the bottom end of the prefabricated piles. In addition, although Patent Document 3 does not state any specific anticipated diameter, it proposes a construction method in which multiple prefabricated piles are bundled together by gluing them or some other method, forming them into a single unit, and then buried together in a simple manner. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Unexamined Patent Publication No. 63-19340 [Patent Document 2] Japanese Patent Application Publication No. 11-6147 [Patent Document 3] JP 2004-162348 A Summary of the Invention [Problem to be solved by the invention]

[0004] In Patent Document 1, there is no description of a means for maintaining the interval between each precast pile or a means for injecting cement milk into the tip, making actual construction difficult. In particular, it could not be applied when the supporting layer was deep and the precast piles had to be buried by connecting them vertically. In addition, in Patent Document 2, the heads of the precast piles are kept at a predetermined interval by using spacers, and the entire bundle of precast piles is buried in a pile hole, so some means was needed to confirm that the predetermined interval was maintained at the bottom ends of the bundle of precast piles. Also, although there is a description that the bundle of precast piles can be buried one by one or two or three at a time, rather than buried together, no specific proposal has been made. Also, when driving precast piles vertically, the entire bundle of precast piles must be supported on the ground, requiring a special jig. In addition, in Patent Document 3, although simple connection by adhesion is possible, the outer peripheries of the bundled prefabricated piles are in contact with each other, so that when driving the piles vertically, connection work using welding or jigs is not possible. [Means for solving the problem]

[0005] This invention solves the above-mentioned problems by dividing a pile hole into a number of pile-retaining compartments by partition lines when viewed in a horizontal plane, inserting a pile insertion rod equipped with a pile-retaining compartment dividing means along the partition lines into the pile hole, and inserting a prefabricated pile into each pile-retaining compartment.

[0006] That is, the basic invention is a method for constructing a bundled foundation pile structure, characterized in that a plurality of prefabricated piles are buried in pile holes filled with a hydraulic material as described below. (1) The pile hole including the supporting ground at its lower end is excavated from the ground using an excavation means. (2) When viewed in a plan view, the horizontal cross section of the pile hole is divided into multiple sections by imaginary partition lines to form pile holding sections, and the pile holding sections are set vertically from the ground to near the bottom of the pile hole. (3) forming a pile insertion rod having a pile-retaining compartment dividing means disposed along the compartment line, and inserting the pile insertion rod into the pile hole; (4) Within each pile-holding area, lowering a precast pile from the ground into the pile hole. (5) Next, the pile insertion rod is pulled up from within the pile hole to the ground. (6) before, during or after the insertion of the pile insertion rod into the pile hole; or Before or after lowering the precast pile, or Before, during or after the pile insertion rod is pulled out of the pile hole, A hydraulic material is injected into the pile hole. (7) Once the hydraulic material has solidified, a bundled foundation pile structure is formed in which the vertically connected prefabricated piles are placed within each pile-retaining compartment of the pile hole.

[0007] In the basic invention, the process of lowering prefabricated piles into each pile holding section is In each pile holding section, the lowermost prefabricated pile is lowered from the ground into the pile hole, while the required number of prefabricated piles from the lowermost prefabricated pile to the uppermost prefabricated pile are lowered while connecting them by conventional means, to form a vertically connected prefabricated pile by connecting the required number of prefabricated piles, and the vertically connected prefabricated piles are buried in the pile hole. This is a method for constructing a bundled foundation pile structure, characterized by the above.

[0008] In addition, in the basic invention, a horizontal load-bearing member is formed having a plate steel material having a height that can be placed along the partition line and at the upper end of the pile hole, After the pile insertion rod is raised above ground, before the hydraulic material hardens, This is a method for constructing a bundled foundation pile structure, characterized in that the horizontal load-bearing member is inserted into the pile hole.

[0009] In addition, in the basic invention, the pile insertion rod is configured by radially connecting a base located in the axial direction of the pile hole to a compartment forming means made of rod-shaped material arranged along the compartment line, and the compartment forming means is arranged at multiple locations in the vertical direction, thereby providing a method for constructing a bundled foundation pile structure.

[0010] The present invention also provides a method for constructing a bundled foundation pile structure, characterized in that the bundled foundation pile structure is constructed as follows. (1) The body of the pile insertion rod is hollow, and an inlet for injecting hydraulic material is formed at its upper end and an outlet for discharging hydraulic material is formed at its lower end. (2) While the pile insertion rod is positioned in the pile hole or while the pile insertion rod is being raised above ground, a hydraulic material is injected into the pile hole from the outlet.

[0011] The above also relates to a method for constructing a bundled foundation pile structure, characterized in that a pile insertion rod is configured as follows. (1) Form an "upper compartment forming means" at a predetermined height and form a "lower compartment forming means" located below it; (2) The rod-shaped material of the "upper compartment forming means" and the rod-shaped material of the "lower compartment forming means" are arranged at approximately the same position in a plan view, (3) Each rod-shaped material of the "upper compartment forming means" is connected to each corresponding rod-shaped member of the "lower compartment forming means" directly below by a vertical guide means. (4) Each of the guide means has its side edges disposed within each of the pile-holding compartments adjacent to each other on either side.

[0012] The present invention also provides a method for constructing a bundled foundation pile structure, characterized in that the pile insertion rod is configured as follows. (1) The guide means is in the form of a plate arranged in a direction perpendicular to the longitudinal direction of the rod-shaped material, and both vertical edges of the plate protrude into each of the adjacent pile-retaining sections. (2) The side edges of the guide means are formed into guide slopes whose width increases from the upper end toward the lower end.

[0013] The present invention also provides a method for constructing a bundled foundation pile structure, characterized in that the pile insertion rod is configured as follows. (1) Arrange the guide slopes of the guide means to be placed in each pile-retaining section in a predetermined shape and position with precast piles placed in each pile-retaining section; (2) The predetermined shape and position are such that the precast pile does not come into contact with the rod-shaped material, And the outer circumference of the prefabricated pile guided by the guide slope does not protrude from the pile hole. The composition was as follows.

[0014] The present invention also provides a method for constructing a bundled foundation pile structure, characterized in that the pile insertion rod is configured as follows. (1) Arrange the guide slopes of the guide means to be placed in each pile-retaining section in a predetermined shape and position with precast piles placed in each pile-retaining section; (2) The specified shape and position are configured so that when the guide slope guides the descent of the precast pile and lowers the precast pile, the lower end of the precast pile does not rest on the rod-shaped material located below.

[0015] The present invention also provides a method for constructing a bundled foundation pile structure, characterized in that the bundled foundation pile structure is constructed as follows. (1) A discharge port is formed at the lower end of the pile insertion rod, and while the discharge port is at the lower end of the pile hole, a normal hydraulic material with a normal hardening strength is first discharged from the discharge port of the main body, and then a high-strength hydraulic material with a high hardening strength is injected; (2) A high-strength hydraulic material layer is formed at the bottom of the pile hole, and a normal-strength hydraulic material layer is formed continuously above the high-strength hydraulic material layer. (3) The pile insertion rod is then retrieved to the ground.

[0016] The present invention also provides a method for constructing a bundled foundation pile structure, characterized in that the bundled foundation pile structure is constructed as follows. (1) forming a discharge port at the lower end of the pile insertion rod, and while the discharge port is at the lower end of the pile hole, first discharging a hydraulic material having high solidification strength from the discharge port of the main body to form a high-strength hydraulic material layer; (2) Next, while pulling up the pile insertion rod, a normal strength hydraulic material is injected from the outlet from above the high strength hydraulic material layer, and the pile insertion rod is retrieved to the ground. (3) A high-strength hydraulic material layer is formed at the bottom of the pile hole, and a normal-strength hydraulic material layer is formed continuously above the high-strength hydraulic material layer.

[0017] In addition, in the basic invention, there is provided a method for constructing a bundled foundation pile structure as follows. (1) While discharging excavated soil to the ground using an excavation means for the on-site construction pile, the pile hole shaft is excavated, and the excavation means for the on-site construction pile is recovered to the ground. (2) Following the pile hole shaft portion, the lower end of the pile hole including the supporting ground is excavated using an excavation means for the precast pile construction method. (3) Next, the excavation means for the precast pile method is withdrawn to the ground while discharging hydraulic material from the excavation means for the precast pile method into the pile hole. (4) Insert a pile insertion rod into the pile hole filled with the hydraulic material.

[0018] In the basic invention, before or during the excavation of the pile hole, a casing is inserted along the inner wall surface of the pile head of the pile hole, and the upper end of the casing is positioned near the ground. This is a method for constructing a bundled foundation pile structure, characterized in that a lateral engagement member attached to the upper end of a pile insertion rod is engaged and held at the upper end of the casing.

[0019] In addition, the number of vertically connected precast piles that make up the bundled foundation piles can be any number (at least two) (Figure 6). Usually, four piles are assumed.

[0020] In addition, the hydraulic material mentioned above is usually cement milk, but other cement-based materials (such as concrete) can also be used as long as they are capable of exerting a specified bearing capacity together with the prefabricated piles when filled between the prefabricated piles in the pile holes and solidified.

[0021] In addition, the injection of cement milk or the like into the pile hole can be performed using a drilling rod or a pile insertion rod, or a separate injection pipe (such as a so-called tremie pipe) can be used. Effect of the Invention

[0022] In this invention, a pile hole is divided into a number of pile retaining sections by dividing lines when viewed in a horizontal plane, a pile insertion rod equipped with a pile retaining section dividing means along the dividing lines is inserted into the pile hole, prefabricated piles are inserted into each pile retaining section, and then the pile insertion rod is pulled up from the pile hole to the ground, thereby ensuring spacing between adjacent prefabricated piles and allowing the prefabricated piles to be reliably buried in predetermined positions, thereby reliably exerting greater bearing capacity corresponding to the larger diameter pile hole. In addition, since the pile insertion rod can be positioned close to the bottom of the pile hole, multiple prefabricated piles can be easily and efficiently buried to a relatively deep position where the prefabricated piles are connected vertically. This reduces the number of pile holes to be excavated, and ensures a large bearing capacity that could not be achieved by conventional construction methods using prefabricated piles. [Brief description of the drawings]

[0023] [Figure 1] 1A to 1I are schematic vertical cross-sectional views illustrating a first construction method of embodiment A of the present invention, and corresponding horizontal cross-sectional views are shown at the bottom ends of 1D to 1I. [Diagram 2] 1A to 1I are schematic vertical cross-sectional views illustrating a second construction method of embodiment A of the present invention, and corresponding horizontal cross-sectional views are shown at the bottom ends of 1D to 1I. [Diagram 3] 10(a) to 10(g) are schematic vertical cross-sectional views illustrating the first half of the steps of the third construction method according to embodiment A of the present invention. [Figure 4] 13(a) to 13(g) are schematic vertical cross-sectional views illustrating the latter steps of the third construction method according to embodiment A of the present invention. [Diagram 5] (a) is a plan view of a bundle pile insertion tool used to implement embodiment A of this invention, (b) a front view of the same bundle pile insertion tool, (c) a front view of a bundle pile insertion tool of a different configuration, and (d) an oblique view of a horizontal load-bearing member used to implement this invention. [Figure 6]FIG. 1(a) shows a plan view of a pile insertion rod for four vertically connected precast piles used to implement embodiment A of this invention, FIG. 1(b) shows a horizontal cross-sectional view of a bundled foundation pile using four vertically connected precast piles, FIG. 1(c) shows a horizontal cross-sectional view of a bundled foundation pile using three vertically connected precast piles, and FIG. 1(d) shows a horizontal cross-sectional view of a bundled foundation pile using five vertically connected precast piles. [Figure 7] FIG. 1 shows a pile insertion rod used in carrying out embodiment I of the present invention, (a) being a front view and (b) being an M-sectional view. [Figure 8] FIG. 11 is a front view of another pile insertion rod used in carrying out embodiment I of the present invention. [Figure 9] 8(a) is a cross-sectional view taken along line N in FIG. 8, and FIG. 8(b) is a cross-sectional view taken along line P in FIG. [Figure 10] FIG. 11 shows another pile insertion rod used in carrying out embodiment A of the present invention, (a) being a side view and (b) being a front view. [Figure 11] (a) is the R cross section of Figure 10(b), (b) is the S cross section of Figure 10(b), and (c) is the Q cross section of Figure 8 and the T cross section of Figure 10(b) with the precast piles in place. [Figure 12] 1A to 1J are schematic vertical cross-sectional views illustrating one method of constructing embodiment 1 of the present invention, and corresponding horizontal cross-sectional views are shown at the bottom ends of 1E to 1J. [Figure 13] 13(a) to 13(j) are schematic vertical cross-sectional views illustrating a second construction method of embodiment A of the present invention, and corresponding horizontal cross-sectional views are shown at the lower ends of 13(e) to 13(j). [Figure 14] 1(a) to 1(i) are schematic vertical cross-sectional views illustrating the first half of the steps of a third construction method according to embodiment A of the present invention. [Figure 15] 1A to 1G are schematic vertical cross-sectional views illustrating the latter steps of the third construction method of embodiment A of the present invention, and corresponding horizontal cross-sectional views are shown at the lower ends of 1B to 1G. [Figure 16] 1(a) to 1(c) are vertical sectional views showing a pile insertion rod with a casing placed in a pile hole according to embodiment I of the present invention. [Figure 17]1(a) and 1(b) are plan views showing the relationship between a pile insertion rod and a precast pile in embodiment I of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] [A] An embodiment using the first pile insertion rod 20

[0025] A1. Materials used in the implementation of the invention

[0026] A-1-1. Pile hole drilling rod 1

[0027] (1) The pile hole drilling rod 1 is composed of a rod body supported on the ground 38 and a drilling head 2 connected to the lower end of the rod body. The pile hole drilling rod 1 (including the rod body) and the drilling head 2 may have any configuration. In this embodiment, a pile hole drilling rod 1A equipped with a drilling head 2A used for on-site pile construction (a construction method in which a reinforcing bar cage and concrete are poured into a pile hole to construct a foundation pile; Earthdris construction method) is used (Figures 1(a), 2(a), and 3(a)). In this case, the drilling head 2A stores the excavated soil inside, and excavation is carried out while pulling the accumulated excavated soil up to the ground 38 each time. Therefore, in the case of this drilling rod 1A, a pipe from a cement milk plant installed on the ground 38 can be connected to a connection port (not shown) at the upper end of the rod body located on the ground 38, so that the supplied cement milk can be supplied into the pile hole 40 from a discharge port (not shown). Also, a drilling rod 1B equipped with a drilling head 2B, which is usually used to dig a pile hole when burying a prefabricated pile, can be used in combination (Fig. 3(c)). For example, the rod body of this drilling rod 1B is made hollow, and the drilling head 2B is configured with swinging drilling arms on both sides of the head body, and a cement milk outlet 3B is provided at the bottom end of the head body. With this drilling rod 1B, the excavated soil can also be discharged to the ground 38 by a spiral or the like (not shown) provided on the rod body.

[0028] A-1-2. Prefabricated pile 9

[0029] (1) The precast pile 9 is made of hollow concrete and has donut-shaped steel end plates at the top and bottom, with structural materials such as PC steel bars and reinforcing bars buried in the concrete between the top and bottom end plates. Here, a vertically connected prefabricated pile 10 is assumed in which multiple prefabricated piles (unit prefabricated piles) 9 are connected vertically by overlapping end plates, rather than a single prefabricated pile. Furthermore, the structure of the prefabricated pile 9 is not limited to that described above. For example, a hollow concrete pile with a steel pipe wrapped around all or part of its periphery may also be used.

[0030] A-1-3. Pile insertion rod 20

[0031] (1) Here, in the horizontal cross section of one pile hole 40, four roughly fan-shaped pile holding sections 17 (17A, 17B, 17C, 17D) are formed by four radial partition lines 15 (15a, 15b, 15c, 15d) in a plan view (Figures 6(a) and 5(a)), and a total of four vertically connected prefabricated piles 10A, 10B, 10C, 10D are inserted into each of the pile holding sections 17A, 17B, 17C, 17D (Figure 6(b)). The pile insertion rod 20 used in this case will be described.

[0032] (2) The pile insertion rod 20 divides the pile hole 40 into pile retaining sections 17A, 17B, 17C, and 17D. The pile insertion rod 20 is composed of a base 21 located approximately at the center 41 of the pile hole 40 in a plan view, and a plurality of section forming members 25a, 25b, 25c, and 25d arranged radially from the outer periphery of the base 21. The base 21 is hollow and tubular, and is formed to a length such that the upper end can be supported on the ground 38 and the lower end can be positioned near the lower end of the pile hole 40 to be formed. Here, since a pile hole 40 as deep as about 10 m to 100 m is assumed, the pile insertion rod 20 is formed by connecting unit pile insertion rods. Of course, the pile insertion rod 20 can also be formed by a single rod without connecting them. Also, with the pile insertion rod 20 having a predetermined length, a connection port (not shown) is formed at the upper end on the ground 38, and a discharge port 23 is formed at the lower end. A pipe from a cement milk plant installed on the ground 38 is connected to the connection port so that the supplied cement milk can be supplied from the discharge port 23 into the pile hole. However, when a separate device is used to inject the cement milk, the discharge port 23 is unnecessary.

[0033] (3) Here, a rod-shaped material is used for the partition forming member 25. In order to hold the vertical connection precast pile 10 (precast pile 9) in each pile holding section 17, it is necessary to have a certain degree of rigidity, and a rod shape is preferred. Also, a triangle (arranged convex upward) or a circle is preferred so that the lower end of the vertical connection precast pile 10 (precast pile 9) coming down from above is difficult to lock (difficult to ride on), but other cross-sectional shapes are also possible. Also, the partition forming member 25 is not limited to a rod-shaped material, and other structures are possible as long as the pile holding section 17 can be formed. For example, a plate-shaped material arranged vertically can also be used (not shown). Also, the partition forming member 25 has its base end fixed to the outer periphery of the base 21, and the length L1 from the axis of the base 21 (that is, the center 41 of the pile hole 40) to the tip is formed to be about one-fourth of the diameter D0 of the pile hole 40 to be formed (Fig. 5(a)). Here, the length L1 of the partition forming member 25 of the pile insertion rod 20 is minimized to a length that can restrict the vertical connection precast pile 10 (or unit precast pile 9) from moving to other pile holding sections 17, and is maximized to a length that does not damage the pile hole wall when inserting and pulling out the pile hole 40. More specifically, One-eighth of the pile hole 40 diameter D0 < length L1 < one-half of D0 It is formed to be about this extent (Fig. 5(a)).

[0034] (4) Here, since the pile hole 40 is partitioned into four (forming four pile holding sections 17A, 17B, 17C, 17D), in a plan view, two partition forming members 25a, 25c are formed of a rod-shaped material in the diameter direction of the pile hole 40. Therefore, in a plan view, the partition forming members 25a, 25c are arranged in the diameter direction, and 25b, 25d are arranged in the diameter direction in a direction perpendicular to this. Furthermore, the compartment forming members 25a that form one compartment line 15a of the same pile holding compartment 17 (e.g., 17a) are formed at multiple locations (multiple height positions) at predetermined intervals H1 in the longitudinal direction of the base 21 (depth direction of the pile hole 40) (Figure 5(b)). For example, in the case of a pile hole 40 (outer diameter D0 = 2000 mm) and a prefabricated pile 9 (outer diameter D1 = 700 mm) are used to divide the pile into four sections, the vertical interval H1 of the partition forming member 25 is as follows: H1=about 50~1000mm In this case, according to the above-mentioned preferable range, the length L1 of the partition forming member 25 is L1=250~1000mm approx. is preferred.

[0035] A-1-4. Horizontal load-bearing member 30

[0036] The horizontal load-bearing member 30 is constructed by arranging four plate materials 31 (31a, 31b, 31c, 31d) along the demarcation lines 15a, 15b, 15c, 15d in a plan view (Fig. 5(d)). The construction method can be any method, such as arranging four radial plates together at the center in a plan view, arranging one plate in the diameter direction and two radial plates in a plan view, or arranging two L-shaped plates by joining the corners of the two plates. Moreover, the horizontal resistance members 30 are placed near the ground 38, usually at about "0 m to 10 m" above the ground 38. The range in which the horizontal resistance members 30 act most effectively is thought to be about "0 m to 5 m" above the ground 38.

[0037] A-2. First method of constructing bundled foundation piles (Fig. 1)

[0038] (1) Based on the required bearing capacity, etc., the diameter and depth of the pile holes 40 and the diameter, structure and number of the required vertically connected precast piles 10A, 10B, 10C and 10D are determined, and the pile holes 40 are set along imaginary partition lines 15a, 15b, 15c and 15d, and four pile-retaining partitions 17A, 17B, 17C and 17D are formed between these imaginary partition lines 15 (Figure 6(a)).

[0039] (2) Using the pile hole drilling rod 1 with an earth drill as the drilling head 2, a pile hole 40 is excavated to a predetermined depth in the usual manner while removing the excavated soil (FIGS. 1(a)(b)). When the excavation is completed, the pile hole drilling rod 1 (earth drill) is raised to the ground 38.

[0040] (3) The pile insertion rod 20 is inserted into the pile hole 40, aligning the center 41 of the pile hole 40 with the center of the base 21. At this time, the pile insertion rod 20 is appropriately connected depending on the depth of the pile hole 40, and is positioned so that the lower end of the pile insertion rod 20 reaches near the bottom 42 of the pile hole 40. The upper end of the pile insertion rod 20 is held immovably on the ground 38 by a conventional method. The sections 17A, 17B, 17C, and 17D of the pile insertion rod 20 are arranged along the imaginary partition lines 15a, 15b, 15c, and 15d of the pile hole 40 in a plan view, so that a total of four pile retaining sections 17A, 17B, 17C, and 17D are formed between adjacent compartment forming members 25a, 25b, 25c, and 25d in a plan view and compartment forming members 25a, 25b, 25c, and 25d (Figures 1(d), 6(a), and 5(a)).

[0041] (4) Next, the lowest precast pile 9 is lowered from the ground 38 into the first pile holding section 17A, and while holding its upper end on the ground, the next precast pile 9 is connected to the lowest precast pile 9, and both precast piles 9, 9 are lowered, and so on up to the topmost precast pile 9 to form a vertically connected precast pile 10A, completing the installation of the vertically connected precast piles 10A into the pile hole 40 (inside the pile holding section 17A) (Figure 1(e)). Similarly, the lowest precast pile 9 is lowered from ground level 38 into the second pile holding section 17B, and while its upper end is held at ground level 38, the next precast pile 9 is connected to the lowest precast pile 9, and both precast piles 9, 9 are lowered, and the rest are connected in the same manner up to the topmost precast pile 9 to form a vertically connected precast pile 10B, and the installation of the vertically connected precast pile 10B into the pile hole 40 of the vertically connected precast pile 10B (inside the second pile holding section 17B) is completed (Figure 1(f)). Similarly, vertically connected prefabricated piles 10C, 10D, which are made by connecting prefabricated piles 9, 9 vertically, are installed in the third pile holding section 17C and the fourth pile holding section 17D (FIG. 1(g)). In the above, after the vertically connected precast pile 10 is installed in the pile holding section 17, construction is performed in the next pile holding section 17, but it is also possible to form the vertically connected precast piles 10 by lowering the precast piles 9, 9 while connecting them in a plurality of pile holding sections 17, 17 in parallel, or in parallel in all pile holding sections 17, 17 (not shown). For example, this is a method in which the precast piles 9, 9 are lowered while connecting them in the pile holding section 17A, while the precast piles 9, 9 are buried while connecting them in the pile holding section 17B, and the vertically connected precast piles 10A, 10B are installed in the pile holding sections 17A, 17B simultaneously or at a slightly different time.

[0042] (5) Next, when the installation of the vertically connected prefabricated piles 10A, 10B, 10C, and 10D has been completed in all pile-holding sections 17A, 17B, 17C, and 17D, a pipe is connected from the cement milk plant to the connection port of the pile insertion rod 20, and while the pile insertion rod 20 is being pulled up to the ground 38, cement milk is discharged from the discharge port 23 at the lower end of the pile insertion rod 20 into the pile hole 40 (FIG. 1(g)). Note that an appropriate amount of cement milk is injected, taking into consideration the insertion of the horizontal load-bearing member 30 in the subsequent process.

[0043] (6) Once the pile insertion rod 20 has been retrieved above ground 38, the horizontal load-bearing member 30 is inserted from above ground 38 into the cement milk layer 44 (inside the pile hole 40 filled with cement milk). Each plate 31a, 31b, 31c, 31d of the horizontal load-bearing member 30 is lowered along the imaginary compartment lines 15a, 15b, 15c, 15d. In practice, the plate is lowered into the gap between each of the vertically connected precast piles 10A, 10B, 10C, 10D so as not to come into contact with each of the vertically connected precast piles 10A, 10B, 10C, 10D. The horizontal load-bearing member 30 is supported on the ground 38 by ordinary means (FIG. 1(i)).

[0044] (7) Once the cement milk has solidified, a bundled foundation pile structure 50 is constructed in which each vertically connected prefabricated pile 10A, 10B, 10C, and 10D is buried evenly (within pile holding sections 17A, 17B, 17C, and 17D) in the pile hole 40 (Figure 1(i) and Figure 6(b)).

[0045] (8) As described above, the number of vertically connected precast piles 10 in the pile hole 40 in plan view is arbitrary. For example, in the case of three vertically connected precast piles 10A, 10B, and 10C, imaginary partition lines 15a, 15b, and 15c are set in the pile hole 40 in plan view, and pile holding partitions 17A, 17B, and 17C are formed using a pile insertion rod 20 (not shown) equipped with three partition forming members. The horizontal strength member 30 is also configured to include each of the plate members 31a, 31b, and 31c. Then, the horizontal strength member 30 is lowered so that each of the plate members 31a, 31b, and 31c is aligned along the imaginary partition lines 15a, 15b, and 15c to form the bundled pile foundation structure 50 (FIG. 6(c)). In addition, when five vertically connected prefabricated piles 10A, 10B, 10C, 10D, and 10E are used, imaginary partition lines 15a, 15b, 15c, 15d, and 10e are set in the pile hole 40 in a plan view, and pile holding sections 17A, 17B, 17C, 17D, and 17E are formed using a pile insertion rod 20 (not shown) equipped with five partition forming members. The horizontal strength member 30 is also configured to include each of the plate members 31a, 31b, 31c, 31d, and 31e. Then, the horizontal strength member 30 is lowered so that each of the plate members 31a, 31b, 31c, 31d, and 31e is aligned along the imaginary partition lines 15a, 15b, 15c, 15d, and 15e to form a bundled pile foundation structure 50 (FIG. 6(d)). The same applies to the following construction methods.

[0046] (9) In the above embodiment, the length and number of precast piles 9 constituting each vertically connected precast pile 10 are also determined by the depth of the supporting ground, etc. Therefore, when the supporting ground is shallow, the precast piles 9 can be left unconnected and only one precast pile 9 can be positioned in each pile-holding section 17 (17a, 17b, ...) (not shown). Alternatively, when the supporting ground is deep but a predetermined supporting force can be exerted mainly by the frictional force of one precast pile 9, only one precast pile 9 can be used without being connected. The same applies to the second and third methods of constructing bundled foundation piles described below.

[0047] A-3. Second method of constructing bundled foundation piles (Fig. 2)

[0048] In this embodiment, the type and injection method of cement milk are different from those in the first construction method.

[0049] (1) As in the above construction method, four pile-retaining sections 17A, 17B, 17C, and 17D are formed within a pile hole 40 by imaginary partition lines 15a, 15b, 15c, and 15d (FIG. 6(a)).

[0050] (2) As in the above construction method, a pile hole drilling rod 1 using an earth drill as the drilling head 2 is used to excavate a pile hole 40 in the usual manner (Figures 2(a)(b)), and when the excavation is completed, the pile hole drilling rod 1 is pulled up to the ground 38. The pile insertion rod 20 is inserted into the pile hole 40 (Figures 2(c)(d)), and pile retaining sections 17A, 17B, 17C, 17D are formed between the rod-shaped materials 25a, 25b, 25c, 25d of the pile insertion rod 20 (Figures 2(e)-(f)).

[0051] (3) Next, when the installation of the vertically connected prefabricated piles 10A, 10B, 10C, and 10D is completed in all pile holding sections 17A, 17B, 17C, and 17D, a pipe is connected to the connection port of the pile insertion rod 20 from a cement milk plant (rich mix), and rich mix cement milk is discharged from the discharge port 23 at the lower end of the pile insertion rod 20 near the bottom 42 of the pile hole 40 to form a high-strength cement milk layer 44b at the lower end of the pile hole 40 (FIG. 2(g)). At this time, the pile insertion rod 20 can also be pulled up to near the top surface of the high-strength cement milk layer 44b to be formed.

[0052] (4) Next, the connection port of the pile insertion rod 20 is switched and connected to a pipe from the cement milk plant (lean mix), and while pulling up the pile insertion rod 20, the lean cement milk is pulled up from the discharge outlet 23 into the pile hole 40, forming a normal cement milk layer 40a on the upper surface of the high-strength cement milk layer 44b, and the pile insertion rod 20 is then pulled up to the ground 38 (Figure 2(g)). In addition, taking into consideration the insertion of the horizontal load-bearing member 30 in a later process, an appropriate amount of cement milk is usually injected into the cement milk layer 40a.

[0053] (5) After the pile insertion rod 20 is retrieved above ground 38, the horizontal load-bearing member 30 is inserted into the pile hole 40 filled with the ordinary cement milk layer 44a from above ground 38. The insertion of the horizontal load-bearing member 30 is the same as in the above-mentioned construction method. That is, each plate 31a, 31b, 31c, 31d of the horizontal load-bearing member 30 is lowered along the imaginary compartment lines 15a, 15b, 15c, 15d. In practice, the plate is lowered into the gaps between the vertically connected precast piles 10A, 10B, 10C, 10D so as not to come into contact with the vertically connected precast piles 10A, 10B, 10C, 10D. The horizontal load-bearing member 30 is held on the ground 38 by ordinary means (FIG. 2(i)).

[0054] (6) Once the cement milk has solidified, a bundled foundation pile structure 50 is constructed in which each vertically connected prefabricated pile 10A, 10B, 10C, and 10D is buried evenly (within pile holding sections 17A, 17B, 17C, and 17D) in the pile hole 40 (Figure 2(i) and Figure 6(b)).

[0055] A4. The third method of constructing the bundled foundation piles (Fig. 3, Fig. 4)

[0056] In this construction method, the method of excavating pile holes, the method of injecting cement milk, and the injection sequence are different from the first construction method.

[0057] (1) As in the above construction method, four pile-retaining sections 17A, 17B, 17C, and 17D are formed within a pile hole 40 by imaginary partition lines 15a, 15b, 15c, and 15d (FIG. 6(a)).

[0058] (2) Using a pile hole drilling rod 1A that uses an earth drill as the drilling head 2A, excavate the shaft portion (upper and middle portions, up to near the supporting ground) of the pile hole 40 in the usual manner (Figures 3(a)(b)). Once drilling is complete, the pile hole drilling rod 1A is pulled up to the ground 38. Next, the drilling rod 1B is inserted into the pile hole 40 by aligning the center 41 of the pile hole with the center of the drilling rod 1B (FIG. 3(c)), and the remaining lower part (down to the supporting ground) is excavated down to the bottom 42 (FIG. 3(d)).

[0059] (3) Next, the drilling rod 1B (drilling head 2B) is pulled up while discharging the rich-mixture cement milk from the discharge port 3B of the drilling rod 1B (drilling head 2B) near the bottom 42 of the pile hole 40 (FIGS. 3(e) and 3(f)). This forms a high-strength cement milk layer 44b at the bottom of the pile hole 40 (FIG. 3(f)).

[0060] (4) Next, the cement milk supplied to the drilling rod 1B at the ground level 38 is switched to lean cement milk, and the lean cement milk is discharged from the discharge outlet 3B of the drilling rod 1B into the pile hole 40 while the drilling rod 1B is continued to be pulled up to the ground level 38, forming a normal-strength cement milk layer 44a on top of the high-strength cement milk layer 44b (Figures 3(g) and 4(a)). In addition, taking into consideration the insertion of the horizontal load-bearing member 30 in a later process, an appropriate amount of cement milk is usually injected into the cement milk layer 40a.

[0061] (5) Next, the pile insertion rod 20 is inserted into the pile hole 40 in which the cement milk is injected and the normal strength cement milk layer 44a is formed on top of the high strength cement milk layer 44b (FIGS. 4(a)(b)), and the pile holding sections 17A, 17B, 17C, and 17D are formed between the rod-shaped materials 25a, 25b, 25c, and 25d of the pile insertion rod 20 (FIGS. 4(a)(b)). Here, the pile insertion rod 20 used does not need to have a function of injecting cement milk, and the base 21 can be solid (rod-shaped) instead of hollow.

[0062] (6) Next, once installation of the vertically connected prefabricated piles 10A, 10B, 10C, and 10D has been completed in all pile holding sections 17A, 17B, 17C, and 17D (Figures 4(c) to (e)), the pile insertion rod 20 is pulled up to the ground 38 (Figure 4(e)).

[0063] (7) Next, when the pile insertion rod 20 is retrieved above ground 38, the horizontal load-bearing member 30 is inserted from above ground 38 into the pile hole 40 filled with the ordinary cement milk layer 44a (FIG. 4(f)(g)). The insertion of the horizontal load-bearing member 30 is the same as the above-mentioned construction. That is, each plate 31a, 31b, 31c, 31d of the horizontal load-bearing member 30 is lowered along the imaginary compartment lines 15a, 15b, 15c, 15d. In practice, the plate is lowered into the gaps between the vertically connected precast piles 10A, 10B, 10C, 10D so as not to come into contact with the vertically connected precast piles 10A, 10B, 10C, 10D. The horizontal load-bearing member 30 is held on the ground 38 by ordinary means (FIG. 4(g)).

[0064] (8) Once the cement milk has solidified, a bundled foundation pile structure 50 is constructed in which each vertically connected prefabricated pile 10A, 10B, 10C, and 10D is buried evenly (within pile holding sections 17A, 17B, 17C, and 17D) in the pile hole 40 (Figures 4(g) and 6(b)).

[0065] [A] An embodiment using the second pile insertion rod 60

[0066] E1. Materials used in the implementation of the invention

[0067] A-1-1. Pile hole drilling rod 1

[0068] The pile hole drilling rod 1 used in this embodiment is similar to that in the previous embodiment.

[0069] A-1-2. Prefabricated piles 9

[0070] The prefabricated pile 9 used in this embodiment is similar to that in the previous embodiment.

[0071] A-1-3. Pile insertion rod 60

[0072] (1) As in the case of the pile insertion rod 20, here, in the horizontal cross section of one pile hole 40, four roughly fan-shaped pile holding sections 17 (17A, 17B, 17C, 17D) are formed by four radial partition lines 15 (15a, 15b, 15c, 15d) in a plan view (see Figure 6(a) and Figure 5(a)), and a total of four vertically connected prefabricated piles 10A, 10B, 10C, 10D are inserted into each of the pile holding sections 17A, 17B, 17C, 17D (Figure 6(b)). In this case, a pile insertion rod 60 used in this embodiment A instead of the pile insertion rod 20 will be described.

[0073] (2) The pile insertion rod 60, which divides the inside of the pile hole 40 into pile retaining sections 17A, 17B, 17C, and 17D, is composed of a base 61 located approximately at the center 41 of the pile hole 40 in a plan view, and a plurality of section forming members 65a, 65b, 65c, and 65d arranged radially from the outer periphery of the base 61 (Figures 7 and 8). A group 65B of compartment forming members 65a, 65b, 65c, and 65d is arranged below a group 65A of compartment forming members 65a, 65b, 65c, and 65d formed at a single height so that the compartment forming members overlap each other vertically in a plan view (FIGS. 7 and 8). The interval H1 between the group 65A of compartment forming members and the group 65B of compartment forming members is, as in the above embodiment, for example, in the case of a pile hole 40 (outer diameter D0=2000 mm) and a prefabricated pile 9 (outer diameter D1=700 mm) is used to divide the area into four sections, H1=about 50~1000mm is formed.

[0074] (3) Similarly to the cross-sectional shape of the compartment forming member 25 in the above-described embodiment A, the cross-sectional shape of the compartment forming member 65 must have a certain degree of rigidity in order to hold the vertically connected prefabricated piles 10 (prefabricated piles 9) within each pile-holding compartment 17, and is preferably rod-shaped. Also, a triangular (arranged convex upward) or circular shape is preferable so that the lower ends of the vertically connected prefabricated piles 10 (prefabricated piles 9) coming down from above are difficult to catch (to ride on), but other cross-sectional shapes are also possible.

[0075] (4) Between the group of compartment forming members 65A and the group of compartment forming members 65B, the compartment forming members 65a, 65a located above and below are connected by the guide member 66a, the compartment forming members 65b, 65b are connected by the guide member 66b, the compartment forming members 65c, 65c are connected by the guide member 66c, and the compartment forming members 65d, 65d are connected by the guide member 66d. Therefore, the compartment forming member 65a of the group of compartment forming members 65A is located at the upper end of the guide member 66a, and the compartment forming member 65a of the group of compartment forming members 65B is located at the lower end of the guide member 66a. The same applies to the guide members 66b, 66c, 66d. The guide member 66a is plate-shaped, with a narrow upper end (horizontal length in a direction perpendicular to the axial direction of the compartment forming member 65) (similar to the width of each compartment forming member 66) and a wide lower end, and a guide slope 67a is formed on the vertical (up-down) side of the guide member 66a. The guide slopes 67a, 67a are arranged in the adjacent pile holding sections 17A, 17B, that is, facing the prefabricated pile 9 (vertically connected prefabricated pile 10) inserted into the pile holding sections 17A, 17B. The guide slopes 67b, 67c, 67d of each guide member 66b, 66c, 66d are the same. Note that one guide member slope 66 with a guide slope 67 is provided for each compartment forming member 65, but two or more can be provided (not shown). The installation position of the guide member 66a is such that the outer surface (or near its concentric circle) of the prefabricated pile 9 to be placed in the pile holding section 17 is located near the contact point 69 with each section forming member 65b, or slightly toward the base 61 than the contact point 69 (Figure 7(b)).

[0076] (5) The attachment position and size of the guide member 66a will now be described in more detail (FIG. 17). The guide member 66 has a function of stably holding the prefabricated pile 9 (vertical connection prefabricated pile 10) arranged in the pile holding section 17. Therefore, for example, in the pile holding section 17A, when the prefabricated pile 9 (vertical connection prefabricated pile 10) and the section forming members 65a, 65b are in contact with each other at the contact points 69, 69, the axial position and size of the section forming member 65b of the guide member 67 are determined so that both the guide slope 67 of the guide member 66 of the section forming member 65a and the guide member 67 of the section forming member 65b are in contact with the prefabricated pile 9 (vertical connection prefabricated pile 10) (FIG. 17(a)). In this state, naturally, the prefabricated pile 9 (vertical connection prefabricated pile 10) fits within the pile holding section 17 and does not protrude from the outer periphery of the pile hole 40. Furthermore, the guide member 66 also has the function of storing the prefabricated piles 9 (vertical connected prefabricated piles 10) in each pile holding section 17 in the pile hole 40. When the prefabricated piles 9 (vertical connected prefabricated piles 10) approach the section forming member 65, the lower end of the prefabricated piles 9 (vertical connected prefabricated piles 10) may be engaged with the section forming member 65 located below, which may prevent the prefabricated piles 9 (vertical connected prefabricated piles 10) from descending any further. In order to prevent this, it is preferable to guide the prefabricated piles 9 (vertical connected prefabricated piles 10) so that they are stored in a state somewhat away from the section forming member 65 (FIG. 17(b)). In this way, the "mounting position in the axial direction of the section forming member 65" and "size" (the protruding length from the surface of the section forming member 65 in a plan view) of the guide member 67 equipped with the guide slope 67 are determined so that the prefabricated piles 9 (vertical connected prefabricated piles 10) can be kept in position in the pile holding section 17 (FIG. 17(b)). In this state, naturally, the prefabricated pile 9 (vertical connected prefabricated pile 10) fits within the pile holding section 17 and does not protrude from the outer periphery of the pile hole 40. Incidentally, currently, the mounting position of the guide member 67 having the guide slope 67, i.e., the distance L1 (mounting position) from the base end of the compartment forming member 65, is set at a position that is approximately "half" the radius of the precast pile 9 (vertically connected precast pile 10) (Fig. 7(b)). From the viewpoint of keeping the "size" of the guide slope 67 of the guide member 67 as small as possible and maintaining the overall balance, the distance L1 (mounting position) of the base end of the compartment forming member 65 is set at a position that is approximately "one-fifth" to "four-fifths" of the radius of the precast pile 9 (vertically connected precast pile 10), but it is considered that, for the same purpose, it is preferable to set it at approximately "one-fifth" to "three-fourths".

[0077] (6) The base 61 is hollow and tubular, and is formed to a length such that the upper end can be supported on the ground 38 and the lower end can be positioned near the lower end of the pile hole 40 to be formed. Since a pile hole 40 as deep as 10 m to 100 m is assumed here, the pile insertion rod 60 is formed by connecting unit pile insertion rods. Of course, the pile insertion rod 60 can also be formed by a single rod without connecting them. Like the pile insertion rod 20, a discharge port 63 is formed at the lower end as required. When used in a connected state, the pile insertion rod 60 located in the middle has a connecting protrusion 63a at the upper end of the base 61 and a connecting recess 63b at the lower end, so that the connecting protrusion 62a and the connecting recess 62b can be connected to each other (FIG. 7(a)). In addition, the lower end of the base 61 has a discharge port 23 for cement milk or the like, similar to the pile insertion rod 20.

[0078] (7) In addition, in this embodiment, a casing (steel pipe for protecting the hole wall) 80 is used at the upper end of the pile hole 40, i.e., near the ground level 38. Therefore, the pile insertion rod 60 located at the top has a lateral locking member 71 attached to the casing 80 (i.e., the opening edge of the pile hole 40, near the ground level 38) slightly below the connecting protrusion 62a at the upper end (Figs. 8 and 10). In one embodiment, four horizontal locking members 71, 71 longer than the radius of the peg hole 40 are attached radially to the base 61 at the same height (at the same position in the length direction of the base 61) (FIG. 8). The material of the horizontal locking members 71, 71 is arbitrary. The lower surface of the lateral locking member 71 is formed with holding portions 72, 72 capable of sandwiching and holding the upper end portion of the casing 80.

[0079] (8) In one embodiment, four lateral locking members 71, 71 longer than the radius of the pile hole 40 can be attached diametrically to the base 61 at the same height (at the same position in the longitudinal direction of the base 61) (FIG. 9). The lateral locking members 71, 71 use H-shaped steel as described above, but any material can be used as long as the structure can hold the pile insertion rods 40, 40 on the ground. In this case, compartment forming members 65, 65 can be provided diametrically at the same height (same position in the longitudinal direction of the base 61) so as to be perpendicular to the diametrically provided horizontal engaging members 71, 71 (FIG. 10).

[0080] (9) In the above, the compartment forming member 55 uses a rod-shaped material similar to the pile insertion rod 20, but the structure is arbitrary as long as it can form the pile holding compartment 17. In addition, the partition forming member 55 has its base end fixed to the outer periphery of the base 51, and the length L1 from the axis of the base 51 (i.e., the center 41 of the pile hole 40) to its tip is the same as that of the pile insertion rod 20 (see Figure 5(a)).

[0081] (10) Also, in the same manner as in the pile insertion rod 20, in the case where the pile hole 40 is partitioned into four (four pile holding sections 17A, 17B, 17C, 17D are formed), two partition forming members 55a, 55c are formed from rod-shaped materials in the diametric direction of the pile hole 40 in a plan view. Therefore, the partition forming members 55a, 55c are arranged in the diametric direction in a plan view, and the members 55b, 55d are arranged in the diametric direction at a right angle to the partition forming members 55a, 55c in a plan view. Furthermore, similar to the pile insertion rod 20, the compartment forming members 55a forming one compartment line 15a of the same pile holding compartment 17 (e.g., 17a) are formed at multiple locations (multiple height positions) at predetermined intervals H1 in the longitudinal direction of the base 21 (depth direction of the pile hole 40) (see Figures 7 and 5(b)). For example, in the case of a pile hole 40 (outer diameter D0 = 2000 mm) and a prefabricated pile 9 (outer diameter D1 = 700 mm) are used to divide the pile into four sections, the vertical interval H1 of the partition forming member 25 is as follows: H1=about 50~1000mm In this case, according to the above-mentioned preferable range, the length L1 of the partition forming member 25 is L1=250~1000mm approx. is preferred.

[0082] (11) Also, a plurality of compartment forming member groups 65A, 66B with guide members 66 can be arranged over the entire length of the base 61 (FIG. 16(a)). In this case, they are usually formed at equal intervals in the axial direction (height direction) of the base 61. Also, a group of compartment forming members 65A, 66B with guide members 66 are arranged on the topmost stage of the base 61 (near the ground 38), and compartment forming members 25, 25 without guide members 66 can be used axially below the base 61 (Figs. 16(b)(c)). The compartment forming members 25, 25 without guide members 66 can be plate-shaped (Fig. 16(b)) or rod-shaped (Fig. 16(c)).

[0083] A-1-4. Horizontal load-bearing member 30

[0084] The prefabricated pile 9 used in this embodiment is similar to that in the previous embodiment.

[0085] A-2. Method for constructing a bundled foundation pile using a second insertion rod 60 (Figure 12. Corresponding to Figure 1)

[0086] (1) Based on the required bearing capacity, etc., the diameter and depth of the pile holes 40, and the diameter, structure and number of the required vertically connected precast piles 10A, 10B, 10C and 10D are determined, and the pile holes 40 are set along imaginary partition lines 15a, 15b, 15c and 15d, and four pile-retaining partitions 17A, 17B, 17C and 17D are formed between these imaginary partition lines 15 (see Figure 6(a)).

[0087] (2) A casing 80 is installed at the planned location for forming a pile hole 40 (FIG. 12(a)). Using a pile hole drilling rod 1 with an earth drill as a drilling head 2, a pile hole 40 is excavated to a predetermined depth in a normal manner while removing the excavated soil (FIGS. 12(b)(c)). When excavation is completed, the pile hole drilling rod 1 (earth drill) is raised above ground 38.

[0088] (3) The pile insertion rod 60 is inserted into the pile hole 40, aligning the center 41 of the pile hole 40 with the center of the base 21. At this time, the pile insertion rod 60 is appropriately connected according to the depth of the pile hole 40, and positioned so that the lower end of the pile insertion rod 60 reaches near the bottom 42 of the pile hole 40. The holding parts of the horizontal locking members 71, 71 at the upper end of the pile insertion rod 60 clamp the upper edge of the casing 80, so that the pile insertion rod 60 is held immovably on the ground 38. The sections 17A, 17B, 17C, and 17D of the pile insertion rod 60 are arranged along the imaginary partition lines 15a, 15b, 15c, and 15d of the pile hole 40 in a plan view, so that a total of four pile retaining sections 17A, 17B, 17C, and 17D are formed between adjacent partition forming members 65a, 65b, 65c, and 65d in a plan view (see Figures 12(e), 6(a), and 5(a)).

[0089] (4) Next, the lowest precast pile 9 is lowered from the ground 38 into the first pile holding section 17A, and while holding its upper end on the ground, the next precast pile 9 is connected to the lowest precast pile 9, and both precast piles 9, 9 are lowered, and so on until the topmost precast pile 9 is connected to form a vertically connected precast pile 10A, completing the installation of the vertically connected precast piles 10A into the pile hole 40 (inside the pile holding section 17A) (Figures 12(f)(g)). Similarly, the lowest prefabricated pile 9 is lowered from the ground 38 into the second pile holding section 17B, and while holding the upper end at the ground 38, the next prefabricated pile 9 is connected to the lowest prefabricated pile 9, and both prefabricated piles 9, 9 are lowered, and so on until the top prefabricated pile 9 is connected to form a vertically connected prefabricated pile 10B, and the installation of the vertically connected prefabricated piles 10B into the pile holes 40 (in the second pile holding section 17B) is completed (FIG. 12(g)). At this time, when the prefabricated piles 9 are inserted into each pile holding section 17, they are guided by the guide members 66 (particularly the guide slopes 67) of the pile insertion rod 60, and are inserted into the predetermined positions in each pile holding section 17. Similarly, vertically connected precast piles 10C, 10D, which are made by connecting precast piles 9, 9 vertically, are installed in the third pile holding section 17C and the fourth pile holding section 17D (Figures 12(g)(h)). In the above, after the vertically connected precast pile 10 is installed in the pile holding section 17, construction is performed in the next pile holding section 17, but it is also possible to form the vertically connected precast piles 10 by lowering the precast piles 9, 9 while connecting them in a plurality of pile holding sections 17, 17 in parallel, or in parallel in all pile holding sections 17, 17 (not shown). For example, this is a method in which the precast piles 9, 9 are lowered while connecting them in the pile holding section 17A, while the precast piles 9, 9 are buried while connecting them in the pile holding section 17B, and the vertically connected precast piles 10A, 10B are installed in the pile holding sections 17A, 17B simultaneously or at a slightly different time.

[0090] (5) Next, when the installation of the vertically connected prefabricated piles 10A, 10B, 10C, and 10D has been completed in all pile-holding sections 17A, 17B, 17C, and 17D, a pipe is connected from the cement milk plant to the connection port of the pile insertion rod 20, and while the pile insertion rod 20 is being pulled up to the ground 38, cement milk is discharged from the discharge port 23 at the lower end of the pile insertion rod 20 into the pile hole 40 (FIG. 12(h)). Note that an appropriate amount of cement milk is injected, taking into consideration the insertion of the horizontal load-bearing member 30 in the subsequent process.

[0091] (6) Once the pile insertion rod 60 has been retrieved above ground 38, the horizontal load-bearing member 30 is inserted from above ground 38 into the cement milk layer 44 (inside the pile hole 40 filled with cement milk) (FIG. 12(i)). Each plate 31a, 31b, 31c, 31d of the horizontal load-bearing member 30 is lowered along the imaginary compartment lines 15a, 15b, 15c, 15d. In practice, the plate is lowered into the gaps between the vertically connected precast piles 10A, 10B, 10C, 10D so as not to come into contact with the vertically connected precast piles 10A, 10B, 10C, 10D. The horizontal load-bearing member 30 is supported on the ground 38 by ordinary means (FIG. 1(j)).

[0092] (7) Once the cement milk has solidified, the bundled foundation pile structure 50 is constructed with the vertically connected prefabricated piles 10A, 10B, 10C, and 10D evenly buried (in the pile holding sections 17A, 17B, 17C, and 17D) in the pile holes 40 (see Fig. 1(j) and Fig. 6(b)). At this time, the casing 80 is left as it is, but it may be pulled out to the ground 38 before or after the horizontal load-bearing member 30 is inserted.

[0093] (8) As in the case of using the first pile insertion rod 20 (FIG. 1), the number of vertically connected precast piles 10 in the pile hole 40 in plan view is arbitrary. For example, in the case of three vertically connected precast piles 10A, 10B, and 10C, imaginary partition lines 15a, 15b, and 15c are set in the pile hole 40 in plan view, and pile holding partitions 17A, 17B, and 17C are formed using a pile insertion rod 20 (not shown) equipped with three partition forming members. The horizontal strength member 30 is also configured to include each plate material 31a, 31b, and 31c. Then, the horizontal strength member 30 is lowered so that each plate material 31a, 31b, and 31c is aligned along the imaginary partition lines 15a, 15b, and 15c to form a bundled pile foundation structure 50 (FIG. 6(c)). In addition, when five vertically connected prefabricated piles 10A, 10B, 10C, 10D, and 10E are used, imaginary partition lines 15a, 15b, 15c, 15d, and 10e are set in the pile hole 40 in a plan view, and pile holding sections 17A, 17B, 17C, 17D, and 17E are formed using a pile insertion rod 20 (not shown) equipped with five partition forming members. The horizontal strength member 30 is also configured to include each plate material 31a, 31b, 31c, 31d, and 31e. Then, the horizontal strength member 30 is lowered so that each plate material 31a, 31b, 31c, 31d, and 31e is aligned along the imaginary partition lines 15a, 15b, 15c, 15d, and 15e to form a bundled pile foundation structure 50 (FIG. 6(d)). The same applies to the following construction methods.

[0094] (9) In the above embodiment, the length and number of precast piles 9 constituting each vertically connected precast pile 10 are also determined by the depth of the supporting ground, etc. Therefore, when the supporting ground is shallow, the precast piles 9 can be not connected and only one precast pile 9 can be positioned in each pile holding section 17 (17a, 17b, ...) (not shown). Alternatively, when the supporting ground is deep but a predetermined supporting force can be exerted mainly by the frictional force of one precast pile 9, only one precast pile 9 can be used without being connected. The same applies to the second and third construction methods of bundled foundation piles described below.

[0095] A-3. Method for constructing a bundled foundation pile using a second pile insertion rod 60 (corresponding to Figures 13 and 2)

[0096] In this embodiment, the type and injection method of cement milk are different from those in the first construction method.

[0097] (1) As in the above construction method, four pile-retaining sections 17A, 17B, 17C, and 17D are formed within a pile hole 40 by imaginary partition lines 15a, 15b, 15c, and 15d (FIG. 6(a)).

[0098] (2) As in the above construction method, a casing 80 is installed at the planned position for forming a pile hole 40 (FIG. 13(a)), and then a pile hole drilling rod 1 using an earth drill as a drilling head 2 is used to excavate the pile hole 40 in a normal construction method (FIGS. 13(b)(c)). Once drilling is complete, the pile hole drilling rod 1 is raised above ground level 38. The pile insertion rod 60 is inserted into the pile hole 40 (Figures 13(d)(e)) and the horizontal engagement members 71, 71 are engaged with the upper edge of the casing 80, forming pile retaining sections 17A, 17B, 17C, 17D between the rod-shaped materials 65a, 65b, 65c, 65d of the pile insertion rod 60 (Figures 13(e)-(h)).

[0099] (3) Next, the installation of the vertically connected precast piles 10A, 10B, 10C, and 10D is completed in all pile holding sections 17A, 17B, 17C, and 17D. At this time, when the precast piles 9 are inserted into each pile holding section 17, they are guided by the guide members 66 (particularly the guide slopes 67) of the pile insertion rod 60, and are inserted into the predetermined positions in each pile holding section 17. After that, a pipe is connected to the connection port of the pile insertion rod 60 from a cement milk plant (rich mix), and rich mix cement milk is discharged from the discharge port 23 at the lower end of the pile insertion rod 60 near the bottom 42 of the pile hole 40 to form a high-strength cement milk layer 44b at the lower end of the pile hole 40 (Figure 13(h)). At this time, the pile insertion rod 60 can also be pulled up to near the upper surface of the high-strength cement milk layer 44b to be formed.

[0100] (4) Next, the connection port of the pile insertion rod 60 is switched and connected to a pipe from the cement milk plant (lean mix), and while pulling up the pile insertion rod 60, the lean mix cement milk is pulled up from the discharge outlet 23 into the pile hole 40, forming a normal cement milk layer 40a on the upper surface of the high-strength cement milk layer 44b, and the pile insertion rod 60 is then pulled up to the ground 38 (Figure 13(h)). In addition, taking into consideration the insertion of the horizontal load-bearing member 30 in a later process, an appropriate amount of cement milk is usually injected into the cement milk layer 40a.

[0101] (5) After the pile insertion rod 60 is retrieved above ground 38, the horizontal load-bearing member 30 is inserted into the pile hole 40 filled with the ordinary cement milk layer 44a from above ground 38. The insertion of the horizontal load-bearing member 30 is the same as in the above-mentioned construction method. That is, each plate 31a, 31b, 31c, 31d of the horizontal load-bearing member 30 is lowered along the imaginary compartment lines 15a, 15b, 15c, 15d. In practice, the plate is lowered into the gaps between the vertically connected precast piles 10A, 10B, 10C, 10D so as not to come into contact with the vertically connected precast piles 10A, 10B, 10C, 10D. The horizontal load-bearing member 30 is held on the ground 38 by ordinary means (FIG. 2(i)). In this case, the casing 80 is left as it is, but may be pulled out to the ground 38 before or after the horizontal load-bearing member 30 is inserted.

[0102] (6) Once the cement milk has solidified, a bundled foundation pile structure 50 is constructed in which each vertically connected prefabricated pile 10A, 10B, 10C, and 10D is buried evenly (within pile holding sections 17A, 17B, 17C, and 17D) in the pile hole 40 (Figure 2(i) and Figure 6(b)).

[0103] A-4. Construction method of the third bundled foundation pile using the second pile insertion rod 60 (Figures 14 and 15)

[0104] In this construction method, the method of excavating pile holes, the method of injecting cement milk, and the injection sequence are different from the first construction method.

[0105] (1) As in the above construction method, four pile-retaining sections 17A, 17B, 17C, and 17D are formed within a pile hole 40 by imaginary partition lines 15a, 15b, 15c, and 15d (FIG. 6(a)).

[0106] (2) A casing 80 is installed at the intended location for forming the pile hole 40 (Figure 14(a)), and a pile hole drilling rod 1A using an earth drill as the drilling head 2A is used to excavate the shaft portion (upper and middle portions, up to the vicinity of the supporting ground) of the pile hole 40 in a normal manner (Figures 14(b)(c)). Once drilling is complete, the pile hole drilling rod 1A is pulled up to the ground 38. Next, the drilling rod 1B is inserted into the pile hole 40 by aligning the center 41 of the pile hole with the center of the drilling rod 1B (Figure 14(d)), and the remaining lower part (down to the supporting ground) is excavated down to the bottom 42 (Figure 14(e)).

[0107] (3) Next, the drilling rod 1B (drilling head 2B) discharges rich-mix cement milk from the discharge port 3B of the drilling rod 1B (drilling head 2B) near the bottom 42 of the pile hole 40 (Figure 14(f)), while pulling up the drilling rod 1B. This forms a high-strength cement milk layer 44b at the bottom of the pile hole 40 (Figure 14(g)).

[0108] (4) Next, the cement milk supplied to the drilling rod 1B at ground level 38 is switched to lean cement milk, and the lean cement milk is discharged from the discharge outlet 3B of the drilling rod 1B into the pile hole 40 (Figure 14(h)). The drilling rod 1B is then pulled back to the ground level 38, forming a normal-strength cement milk layer 44a on top of the high-strength cement milk layer 44b (Figures 14(i), 15(a)). In addition, taking into consideration the insertion of the horizontal load-bearing member 30 in a later process, an appropriate amount of cement milk is usually injected into the cement milk layer 40a.

[0109] (5) Next, the pile insertion rod 60 is inserted into the pile hole 40 in which the cement milk is injected and the normal strength cement milk layer 44a is formed on top of the high strength cement milk layer 44b (FIGS. 15(b)(c)), and the pile holding compartments 17A, 17B, 17C, 17D are formed between the rod-shaped compartment forming members 55a, 55b, 55c, 55d of the pile insertion rod 60 (FIGS. 4(a)(b)). Here, the pile insertion rod 60 used does not need to have a function of injecting cement milk, and the base 61 can be solid (rod-shaped) instead of hollow.

[0110] (6) Next, once installation of the vertically connected precast piles 10A, 10B, 10C, and 10D has been completed in all pile holding sections 17A, 17B, 17C, and 17D (Figures 15(c) to (e)), the pile insertion rod 60 is pulled up to the ground 38 (Figure 15(e)).

[0111] (7) Next, when the pile insertion rod 60 is retrieved above ground 38, the horizontal load-bearing member 30 is inserted from above ground 38 into the pile hole 40 filled with the ordinary cement milk layer 44a (FIG. 15(f)(g)). The insertion of the horizontal load-bearing member 30 is the same as the above-mentioned construction. That is, each plate 31a, 31b, 31c, 31d of the horizontal load-bearing member 30 is lowered along the imaginary compartment lines 15a, 15b, 15c, 15d. In practice, the plate is lowered into the gaps between the vertically connected precast piles 10A, 10B, 10C, 10D so as not to come into contact with the vertically connected precast piles 10A, 10B, 10C, 10D. The horizontal load-bearing member 30 is held on the ground 38 by ordinary means (FIG. 4(g)). At this time, the casing 80 is left as it is, but it may be pulled out to the ground 38 before or after the horizontal load-bearing member 30 is inserted.

[0112] (8) Once the cement milk has solidified, a bundled foundation pile structure 50 is constructed in which each vertically connected prefabricated pile 10A, 10B, 10C, and 10D is buried evenly (within pile holding sections 17A, 17B, 17C, and 17D) in the pile hole 40 (Figures 4(g) and 6(b)). [Explanation of symbols]

[0113] 1, 1A, 1B Pile hole drilling rod 2, 2A, 2B Drilling Head 3B Cement milk outlet of pile hole drilling rod 1B 9 Prefabricated piles 10, 10A, 10B, 10C, 10D, 10E Vertically connected prefabricated piles 15, 15a, 15b, 15c, 15d, 15e Lotteries (imaginary) 17, 17A, 17B, 17C, 17D, 17E Pile-retaining sections 20 Pile Insertion Rod 21 Base of pile insertion rod (rod body) 23 Pile insertion rod outlet 25, 25a, 25b, 25c, 25d, 25e Compartment forming members (rod-shaped materials) 30 Horizontal load-bearing members 31, 31a, 31b, 31c, 31d, 31e Plates for horizontal load-bearing members 38 Ground 40 Pile hole 41 Center of the Pile Hole 42 Bottom of the Pile Hole 44 Cement Milk 44a Normal strength cement milk layer 44b High-strength cement milk layer 50 Bundled foundation pile structure 60 Pile Insertion Rod 61 Base of pile insertion rod (rod body) 62a Base connecting protrusion 62b Connection recess at base 65A, 65B Compartment forming members 65, 65a, 65b, 65c, 65d Compartment forming members 66, 66a, 66b, 66c, 66d Guide members 67 Guide bevel of guide member 67a Upper end of guide slope 67b Lower end of guide slope 69 Near the contact point (with prefabricated pile) of the partition forming member 71 Lateral retaining member for pile insertion rod 72 Retaining portion of horizontal locking member 80 Casing

Claims

1. A method for constructing a bundled foundation pile structure, comprising burying a plurality of prefabricated piles in a pile hole filled with a hydraulic material as follows. (1) The pile hole including the supporting ground at its lower end is excavated from the ground using an excavation means. (2) When viewed in a plan view, the horizontal cross section of the pile hole is divided into multiple sections by imaginary partition lines to form pile holding sections, and the pile holding sections are set vertically from the ground to near the bottom of the pile hole. (3) forming a pile insertion rod having a pile-retaining compartment dividing means disposed along the compartment line, and inserting the pile insertion rod into the pile hole; (4) Within each pile-holding area, lowering a precast pile from the ground into the pile hole. (5) Next, the pile insertion rod is pulled up from within the pile hole to the ground. (6) before, during or after the insertion of the pile insertion rod into the pile hole; or Before or after lowering the precast pile, or Before, during or after the pile insertion rod is pulled out of the pile hole, A hydraulic material is injected into the pile hole. (7) Once the hydraulic material has solidified, a bundled foundation pile structure is formed in which the vertically connected prefabricated piles are placed within each pile-retaining compartment of the pile hole.

2. A process of lowering a prefabricated pile into each pile-holding compartment, In each pile holding section, the lowermost prefabricated pile is lowered from the ground into the pile hole, while the required number of prefabricated piles from the lowermost prefabricated pile to the uppermost prefabricated pile are lowered while connecting them by conventional means, to form a vertically connected prefabricated pile by connecting the required number of prefabricated piles, and the vertically connected prefabricated piles are buried in the pile hole. A method for constructing a bundled foundation pile structure according to claim 1.

3. Form a horizontal load-bearing member having a plate steel material of a height that can be placed along the lot line and at the upper end of the pile hole, After the pile insertion rod is raised above ground, before the hydraulic material hardens, The method for constructing a bundled foundation pile structure according to claim 1, further comprising inserting the horizontal load-bearing member into the pile hole.

4. A method for constructing a bundled foundation pile structure as described in claim 1, wherein the pile insertion rod is constructed by radially connecting a base located in the axial direction of the pile hole and a compartment forming means made of rod-shaped material arranged along the compartment line to the base, and the compartment forming means is arranged at multiple locations in the vertical direction.

5. A method for constructing a bundled foundation pile structure according to claim 4, characterized in that the bundled foundation pile structure is constructed as follows. (1) The body of the pile insertion rod is hollow, and an inlet for injecting hydraulic material is formed at its upper end and an outlet for discharging hydraulic material is formed at its lower end. (2) While the pile insertion rod is positioned in the pile hole or while the pile insertion rod is being raised above ground, a hydraulic material is injected into the pile hole from the outlet.

6. The method for constructing a bundled foundation pile structure according to claim 4, characterized in that the pile insertion rod is constructed as follows. (1) Form an "upper compartment forming means" at a predetermined height and form a "lower compartment forming means" located below it; (2) The rod-shaped material of the "upper compartment forming means" and the rod-shaped material of the "lower compartment forming means" are arranged at approximately the same position in a plan view, (3) Each rod-shaped material of the "upper compartment forming means" is connected to each corresponding rod-shaped member of the "lower compartment forming means" directly below by a vertical guide means. (4) Each of the guide means has its side edges disposed within each of the pile-holding compartments adjacent to each other on either side.

7. The method for constructing a bundled foundation pile structure according to claim 6, characterized in that the pile insertion rod is constructed as follows. (1) The guide means is in the form of a plate arranged in a direction perpendicular to the longitudinal direction of the rod-shaped material, and both vertical edges of the plate protrude into each of the adjacent pile-retaining sections. (2) The side edges of the guide means are formed into guide slopes whose width increases from the upper end toward the lower end.

8. The method for constructing a bundled foundation pile structure according to claim 6, characterized in that the pile insertion rod is constructed as follows. (1) Arrange the guide slopes of the guide means to be placed in each pile-retaining section in a predetermined shape and position with precast piles placed in each pile-retaining section; (2) The predetermined shape and position are such that the precast pile does not come into contact with the rod-shaped material, And the outer circumference of the prefabricated pile guided by the guide slope does not protrude from the pile hole. The composition was as follows.

9. The method for constructing a bundled foundation pile structure according to claim 6, characterized in that the pile insertion rod is constructed as follows. (1) Arrange the guide slopes of the guide means to be placed in each pile-retaining section in a predetermined shape and position with precast piles placed in each pile-retaining section; (2) The specified shape and position are configured so that when the guide slope guides the descent of the precast pile and lowers the precast pile, the lower end of the precast pile does not rest on the rod-shaped material located below.

10. A method for constructing a bundled foundation pile structure according to claim 5, characterized in that the structure is constructed as follows. (1) A discharge port is formed at the lower end of the pile insertion rod, and while the discharge port is at the lower end of the pile hole, a normal hydraulic material with a normal hardening strength is first discharged from the discharge port of the main body, and then a high-strength hydraulic material with a high hardening strength is injected; (2) A high-strength hydraulic material layer is formed at the bottom of the pile hole, and a normal-strength hydraulic material layer is formed continuously above the high-strength hydraulic material layer. (3) The pile insertion rod is then retrieved to the ground.

11. A method for constructing a bundled foundation pile structure according to claim 5, characterized in that the structure is constructed as follows. (1) forming a discharge port at the lower end of the pile insertion rod, and while the discharge port is at the lower end of the pile hole, first discharging a hydraulic material having high solidification strength from the discharge port of the main body to form a high-strength hydraulic material layer; (2) Next, while pulling up the pile insertion rod, a normal strength hydraulic material is injected from the outlet from above the high strength hydraulic material layer, and the pile insertion rod is retrieved to the ground. (3) A high-strength hydraulic material layer is formed at the bottom of the pile hole, and a normal-strength hydraulic material layer is formed continuously above the high-strength hydraulic material layer.

12. A method for constructing the bundled foundation pile structure according to claim 1, which is configured as follows. (1) While discharging excavated soil to the ground using an excavation means for the on-site construction pile, the pile hole shaft is excavated, and the excavation means for the on-site construction pile is recovered to the ground. (2) Following the pile hole shaft portion, the lower end of the pile hole including the supporting ground is excavated using an excavation means for the precast pile construction method. (3) Next, the excavation means for the precast pile method is withdrawn to the ground while discharging hydraulic material from the excavation means for the precast pile method into the pile hole. (4) Insert a pile insertion rod into the pile hole filled with the hydraulic material.

13. Before or during the excavation of the pile hole by the excavation means, a casing is inserted along the inner wall surface of the pile head of the pile hole, and the upper end of the casing is positioned near the ground; A method for constructing a bundled foundation pile structure as described in claim 1, characterized in that a lateral locking member attached to the upper end of the pile insertion rod is locked and held at the upper end of the casing.

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