Construction method for temporary piles installed in the basement of existing structures

Abstract

To provide a construction method capable of safely and easily installing a temporary pile in a basement floor of an existing building through a through-hole of each basement floor.SOLUTION: The construction method for installing the temporary pile in the basement floor of the existing building comprises: (1) a step of providing through-holes in floor slabs B1FL-B3FL of the basement floor and a foundation batholith B4FL located below; (2) a step of forming a casing 2 and an earth auger 4 which is rotated and lifted in the casing 2 through the through-holes; (3) a step of drilling a pile hole A in the ground below the basement floor while rotating the earth auger 4 in the casing 2; (4) a step of removing the casing 2 and the earth auger 4 from the basement floor; and (5) a step of erecting the temporary pile in the basement floor through the floor slabs B1FL-B3FL and the foundation batholith B4FL, and erecting a lower end thereof in the pile hole A.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a construction method of temporary piles installed through the remaining basement floors during the reconstruction work of existing buildings. For example, it is used in the construction of earth retaining piles that support the structure of the remaining basement floors and the ground around the structure, and foundation piles that support the formwork floor used as a work yard during the demolition of the basement floors.

Background Art

[0002] When constructing earth retaining piles or foundation piles in geotechnical engineering, usually, steel plates are laid on the site, a pile driver is installed on top of them, and a pile hole is drilled by an earth auger equipped with the pile driver, and then an H-shaped steel is inserted. This is a common method.

[0003] In addition, in the reconstruction work of existing buildings where an existing building with a basement floor is demolished and a new building is constructed on the site, prior to the construction, earth retaining support work is installed to support the structure such as the walls and columns of the basement floor and the ground around the structure.

[0004] In addition, as the demolition of the basement floor progresses, the 1FL floor (the ceiling slab of the basement first floor) as a work yard disappears, so a work platform is installed as a substitute work yard. When the demolition progresses to the lowest floor, the ground below the lowest floor may be partially excavated.

[0005] In this series of construction work, earth retaining piles that support the structure such as the walls and columns of the basement floor and the ground around the structure, shelf piles that support the cross beams of the earth retaining support work, foundation piles that support the work platform, and partition piles are constructed around when partially excavating the ground.

[0006] In addition, these earth retaining piles may be installed through the remaining basement floors, especially when demolishing existing buildings that fill the entire site, because there is no empty space around.

[0007] Conventionally, as a method of installing these temporary piles through the remaining basement floors, for example, the method shown in FIG. 8 is known.

[0008] To briefly explain the construction method for the temporary piles shown in Figure 8, (1) After demolishing and removing the above-ground floor of the existing building, through holes 11 to 14 are made in the floor slab 1FL of the above-ground first floor (ceiling slab of the first basement floor), the floor slabs B1FL to B3FL of each basement floor located below the floor slab 1FL, and the foundation base slab (pressure-resistant slab in contact with the ground) B4FL located below them. (2) Next, the earth auger 4 is inserted between the floor slab 1FL of the first floor above ground and the floor slabs B3FL and foundation base B4FL of each basement floor located below the floor slab 1FL, passing through the through holes 11 to 14 of each floor, and the pile hole A is drilled by rotating and inserting the earth auger 4 into the ground below the foundation base B4FL.

[0009] (3) Next, a solidifying agent such as cement grout is injected into the pile hole A, and the earth auger 4 is pulled up and removed. (4) Then, through the through holes 11 to 14 on each floor, temporary piles (mainly H-shaped steel) are erected between the floor slabs B1FL to B3FL and the foundation base plate B4FL of each underground floor from the floor slab 1FL of the first floor above ground, and the lower end of the pile is erected into the pile hole A. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] Japanese Patent Publication No. 2020-125630 [Patent Document 2] Japanese Patent Publication No. 2019-31856 [Overview of the Initiative] [Problems that the invention aims to solve]

[0011] However, with this temporary pile construction method, the earth auger 4 is exposed to each floor of the basement, so there is a risk of accidental contact with it by workers in the basement. Therefore, it was necessary to install a safety fence 8 as a safety measure.

[0012] Furthermore, the earth auger 4 is usually extended by adding extensions in the axial direction, and the earth augers are connected to each other by pins. As a result, there is a large lateral sway when drilling pile holes, and therefore it is necessary to attach a brace 9 to the slab close to the drilling start position, which requires extra cost and effort for its manufacture and installation.

[0013] Furthermore, the excavated soil adhering to the Earth Auger 4 could scatter onto the floors of each level, potentially soiling them and interfering with other work on each level.

[0014] This invention was made to solve the above problems, and aims to provide a method for constructing temporary piles that can be used as retaining piles or platform piles during the reconstruction of existing buildings, etc., in an extremely safe and efficient manner. [Means for solving the problem]

[0015] This invention relates to the construction of temporary piles installed in the basement of an existing structure, penetrating each floor of the basement. direction The law is characterized by including the following steps:

[0016] (1) The process of creating through holes in the floor slabs of each underground floor of the existing structure. (2) The step of installing the casing and the earth auger which rotates and moves up and down inside the casing by passing the through hole through the underground floor. (3) A step of drilling a pile hole in the ground below the basement floor by lowering the earth auger inside the casing while rotating it. (4) The step of removing the casing and the earth auger from the basement floor. (5) The basement floor each floor The aforementioned Floor slide B The process of inserting the temporary pile through the through hole and then inserting its lower end into the pile hole.

[0017] Charge the earth auger into the casing, and drive the casing and the earth auger into the basement together, and remove them from the basement, so that the operation of driving and removing the casing and the earth auger can be carried out very efficiently.

[0018] In addition, the casing is supported by a casing fixture on the floor slab of the basement, and the casing fixture is clamped between the floor slab of the basement and a leader to which the earth auger is attached and erected on the floor slab, so that the casing can be fixed very simply and firmly.

Effect of the Invention

[0019] According to the present invention, for example, temporary piles such as shoring piles that support the remaining basement structure and the ground around the structure, and formwork piles that support the formwork floor used as a work yard during basement demolition can be constructed very safely and efficiently.

[0020] In particular, since the entire length of the earth auger driven into the basement is completely covered by the casing, the safety of the workers working in the basement can be ensured.

[0021] In addition, the earth auger during drilling is guided by the casing, so that the lateral vibration of the casing is prevented, and the pile hole for driving the lower end of the temporary pile can be reliably drilled. In addition, there is no need to separately install a jig for preventing the earth auger from swaying in the basement. Furthermore, the excavated soil discharged by the excavation of the earth auger does not scatter into the basement.

Brief Description of the Drawings

[0022] [Figure 1] It is a partial longitudinal sectional view of the basement structure showing the construction method of the temporary pile installed in the basement of the existing building of the present invention. [Figure 2] It is an enlarged view of the portion having the through hole on the first basement floor in FIG. ①, FIG. (a) is an enlarged perspective view, and FIG. (b) is an enlarged longitudinal sectional view. [Figure 3] Figure (a) shows the construction procedure of the present invention, and Figure (b) shows a partial longitudinal cross-sectional view of the underground structure, illustrating the process of forming through-holes in the floor slabs of each underground floor, and the process of installing casings with earth augers embedded in them by passing them through the through-holes of each underground floor. [Figure 4] Figures (a) and (b) show the construction procedure of the present invention, and are partial longitudinal cross-sectional views of the underground structure showing the process of driving an earth auger to drill pile holes in the ground below the foundation base B4FL. [Figure 5] Figures (a) and (b) show the construction procedure of the present invention, and are partial longitudinal cross-sectional views of the underground floor structure showing the process of lifting and removing the casing containing the earth auger after drilling is complete. [Figure 6] This is a partial vertical cross-sectional view of the underground structure illustrating the construction procedure of the present invention, showing the process of erecting a casing containing an earth auger by passing it through the next penetration hole on each underground floor. [Figure 7] This is a side view of the casing and the upper end portion of the earth auger installed within the casing. [Figure 8] This is a partial vertical cross-sectional view of the basement structure, showing a conventional method for constructing temporary piles installed in the basement of an existing building. [Modes for carrying out the invention]

[0023] Figures 1 to 6 illustrate the method of driving temporary piles, such as retaining piles or platform piles, into the basement of an existing structure (hereinafter referred to as "existing building").

[0024] In the diagram, through-holes 11 to 14 are formed so as to overlap on the same vertical line in the floor slab of the first floor above ground (ceiling slab of the first basement floor) 1FL, the floor slabs B1FL to B3FL of each basement floor located below the floor slab 1FL of the first floor above ground, and the foundation base of the lowest floor located below them (pressure-resistant slab (base) in contact with the ground).

[0025] Furthermore, casing 2 is installed vertically through the through-holes 11, 12, and 13 in the floor slabs of each floor, between the floor slabs B1FL to B3FL and the foundation base slab B4FL of each basement floor located below the floor slab 1FL.

[0026] Furthermore, the leader 3 of the excavator (not shown in the figure) is erected vertically on the floor slab 1FL, close to the through hole 11, and a reduction gear (not shown in the figure) is installed on the leader 3 as a power source to drive (rotate) the earth auger 4, which will be described later. The reduction gear is installed to move up and down along the leader 3 with the earth auger 4 while rotating the earth auger 4.

[0027] The upper end portion 2a of the casing 2 penetrates the through-hole 11 of the floor slab 1FL, rises up a predetermined length from the upper surface of the floor slab 1FL, and is guided by the casing fixing device 5 to prevent lateral movement within the through-hole 11 of the floor slab 1FL.

[0028] The casing fastener 5 is formed in the shape of a rectangular plate, with a circular through-hole 5a formed approximately in the center. The casing fastener 5 is installed on the floor slab 1FL, and the upper end portion 2a of the casing 2 passes through the through-hole 5a. The peripheral edge of the through-hole 5a is welded to the peripheral wall of the casing 2.

[0029] Furthermore, one end portion 5b of the casing fastener 5 in the long direction is sandwiched between the floor slab 1FL and the lower end portion 3a of the leader 3, thereby detachably fixing the casing fastener 5 to the floor slab 1FL.

[0030] Furthermore, if a guide rib (not shown in the figure) is formed on the upper surface of the casing fastener 5, extending in an annular shape along the outer circumferential surface of the lower end portion 3a of the leader 3, it is possible to prevent the lower end portion of the leader 3 from shifting laterally due to vibrations during drilling, and this allows the upper end portion of the casing 2 to be firmly and easily fixed onto the floor slab 1FL.

[0031] The lower end of the casing 2 is positioned slightly higher than the upper surface of the foundation slab B4FL, and the through-hole 14 formed in the foundation slab B4FL is open to the lowest floor of the foundation slab B4FL.

[0032] As a result, the excavated soil from the earth auger 4 is discharged onto the foundation base B4FL through the through-hole 14 in the foundation base B4FL.

[0033] The earth auger 4 is continuously installed between floor slab 1FL and floor slab 3FL, passing through the casing 2, and its upper end is detachably connected to a reduction gear (not shown) installed on the leader 3. The earth auger 4 rotates with the reduction gear and moves up and down within the casing 2, rotating along the leader 3 together with the reduction gear.

[0034] This allows for the drilling of pile holes A in the ground below the foundation slab B4FL, into which the lower ends of temporary piles, such as retaining piles or platform piles, will be driven.

[0035] Furthermore, after the casing 2 and earth auger 4 are removed, temporary piles, which will be used as retaining piles or platform piles, will be continuously inserted through the through holes 11, 12, 13, and 14 on each floor, with their lower ends being driven into the pile holes A. In addition, a solidifying agent is injected into the pile holes A, thereby fixing the lower ends of the temporary piles driven into the pile holes A within the pile holes A.

[0036] Next, we will explain the construction method for temporary piles, such as retaining piles or platform piles, that are installed by penetrating the remaining underground floors.

[0037] (1) First, through holes 11, 12, 13, and 14 are formed in the floor slab of the first floor above ground (ceiling slab of the first basement floor) 1FL of the existing building, and in the floor slabs B1FL to B3FL of each basement floor located below said floor slab 1FL, and in the foundation base slab B4FL located below them, respectively. The through-holes 11, 12, 13, and 14 on each floor are formed so that they overlap on the same vertical line on each floor, and their inner diameter is formed to a size that does not interfere when erecting the casing 2. It is preferable to form them as small in diameter as possible for supporting the casing 2.

[0038] (2) Next, the casing 2 is erected between the floor slab 1FL and the floor slabs B1FL to B3FL of each basement floor located below the floor slab 1FL, with the casing 2 passing vertically through the through holes 11, 12, and 13 of each floor. At this time, the casing 2 is lifted vertically into the through holes 11, 12, and 13 of each floor using the crane 6. In addition, the casing fixing device 5 is installed on the floor slab 1FL, and the upper end portion 2a of the casing 2 is passed through the through hole 5a of the casing fixing device 5.

[0039] (3) Next, the leader 3 of the excavator (not shown in the figure) is erected on the floor slab 1FL. At this time, the lower end 3a of the leader 3 is placed on the end 5b of the casing fixing device 5, thereby clamping the end 5b of the casing fixing device 5 between the floor slab 1FL and the lower end 3a of the leader 3. This allows the upper end 2a of the casing 2 to be fixed on the floor slab 1FL by the casing fixing device 5 so as not to sway laterally. Furthermore, guide ribs (not shown in the figure) are formed to rise in an annular shape along the outer circumference of the lower end of the leader 3, which prevents the lower end of the leader 3 from shifting laterally due to vibrations during drilling.

[0040] (4) Next, the earth auger 4 is erected into the casing 2 using the crane 6, and the upper end of the earth auger 4 is connected to the reduction gear (not shown) installed on the leader 3. Furthermore, when installing casing 2, the earth auger 4 is placed inside casing 2 on the ground, and casing 2 and earth auger 4 are erected together using crane 6. This allows for simultaneous installation of casing 2 and earth auger 4, significantly improving work efficiency (see Figure 5(b)).

[0041] In this case, the casing 2 and the earth auger 4 can be easily temporarily fixed together to prevent them from separating by simply inserting a fixing pin (commonly known as a "hairpin groove") 7 into the side of the casing 2 so that it passes through the gaps between the blades of the earth auger 4 (see Figure 5). The fixing pin 7 is made of steel or similar material, and a pin hole 2b is formed in the side of the casing 2 through which the fixing pin 7 penetrates in a direction perpendicular to the pipe axis. By using steel material capable of sufficiently withstanding the weight of the falling earth auger 4 as the fixing pin 7, safety during the operation can be ensured.

[0042] (5) Next, the reduction gear (not shown in the diagram) is activated to rotate the earth auger 4 and lower it along the leader 3 inside the casing 2, thereby drilling a pile hole A in the ground below the foundation base B4FL. Furthermore, the excavated soil removed during drilling is discharged onto the foundation base B4FL through the through-hole 14 formed in the foundation base B4FL.

[0043] (6) Once drilling of pile hole A is complete, the reduction gear (not shown in the diagram) is activated to pull the earth auger 4 up along the leader 3 inside the casing 2 to the upper end of the casing 2. The upper end is then detached from the reduction gear, a wire is wrapped around the casing 2, and the earth auger 4 is removed from the leader 3 using the crane 6. Following the removal of the earth auger 4, the casing 2 is removed using the crane 6.

[0044] When removing the earth auger 4 and casing 2, the earth auger 4 is left inside the casing 2 and secured inside the casing 2 with fixing pins 7. Then, the earth auger 4 is detached from the gearbox, and the casing 2 and earth auger 4 are removed together using a crane 6, which is preferable as it allows for the simultaneous removal of the casing 2 and earth auger 4.

[0045] (7) Next, a solidifying agent is injected into the pile hole A, and temporary piles to be used as retaining piles or platform piles are driven through the through-holes 11, 12, 13, and 14 on each underground floor using the crane 6, and the lower end of the temporary pile is driven into the pile hole A to complete the installation of the temporary piles. [Industrial applicability]

[0046] This invention enables the extremely safe construction of temporary piles, such as retaining piles to support the remaining basement structure and the surrounding ground when rebuilding an existing building, and platform piles to support the platform floor used as a work yard during basement demolition. [Explanation of Symbols]

[0047] 11, 12, 13, 14 through holes 2 Casing 2a Upper end of casing 2b Pin hole 3 Leader 4 Earth Auger 5. Casing fasteners 5a through hole 5b One end side 6 Cranes 7 Fixing pins 1FL: Ground floor slab (basement ceiling slab) Floor slabs on each basement level from B1FL to B3FL B4FL Foundation base (pressure-resistant slab in contact with the ground) A pile hole

Claims

1. A method for constructing temporary piles to be installed in the basement of an existing structure, characterized by including the following steps. (1) The process of creating through holes in the floor slabs of each underground floor of the existing structure. (2) The step of installing the casing and the earth auger which rotates and moves up and down inside the casing by passing the through hole through the underground floor. (3) A step of drilling a pile hole in the ground below the basement floor by lowering the earth auger inside the casing while rotating it. (4) The step of removing the casing and the earth auger from the basement floor. (5) The step of inserting the temporary piles into the underground floors by passing them through the through holes in the floor slabs of each underground floor, and inserting the lower ends of the piles into the pile holes.

2. A method for constructing a temporary pile according to claim 1, characterized in that the earth auger is placed in the casing, the casing and the earth auger are erected together in the basement, and then removed from the basement.

3. A method for constructing temporary piles according to claim 1 or 2, characterized in that the casing is fixed to the floor slab of the underground floor by a casing fixing device.

4. A temporary pile construction device for installing temporary piles in the basement of an existing structure, comprising: a casing installed through the floor slabs of each floor of the existing structure; a casing fixing device for fixing the upper end of the casing to the floor slab; an earth auger erected inside the casing and rotating and moving up and down inside the casing to drill a pile hole for erecting the lower end of the temporary pile in the ground below the basement; and a leader erected on the floor slab and to which a reduction gear for driving the earth auger is attached.

5. The temporary pile construction device according to claim 4, wherein the casing fixing device has a through hole through which the casing passes, and is sandwiched between the floor slab of the underground floor and the leader.

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