JP6752416B2 - Ground reinforcement method - Google Patents

Description

The present invention relates to a ground reinforcement method in which a casing steel pipe is rotationally penetrated into the ground, a cement-based injection material for piles such as concrete is injected, and then the casing steel pipe is pulled out to construct a concrete columnar reinforcing body.

As a ground reinforcement method of this type, there is a pile burying method described in Patent Document 1. Explaining by using the reference numerals in the cited document 1, in this method, the tip head 1 having the wing body 3 extending outward is detachably attached to the lower end portion of the tubular casing 10, and the casing is attached. And, while rotating the tip head, it is embedded in the ground, then a reinforcing member (reinforcing bar cage R) is inserted inside the casing, and then concrete before hardening (ready-mixed concrete C) is put inside the casing. After that, the casing is pulled out from the ground in a state where the tip head is dismounted.
This construction method is a construction method in which reinforcing bars are inserted into a casing embedded in the ground and concrete is injected, and a reinforced concrete pile is constructed.
Further, the tip head 1 has a simple flat disk (bottom wall 2a) welded and fixed to the lower end surface of the tubular main body 2, and a wing body 3 formed of two divided plates 3a and 3b is attached to the outer peripheral surface of the main body 2. It is a structure fixed by welding.

JP 2006-77388

As described above, the construction method of Patent Document 1 is a construction method of constructing a reinforced concrete pile, and the tip head 1 to be used is a mere flat disk (bottom wall 2a) whose lower end surface is the lower end surface of the tubular main body 2. ), And the wing body 3 is fixed as a separate member to the outer peripheral surface of the tubular main body 2.
The construction method of Patent Document 1 is intended to obtain a foundation pile capable of exerting a strong bearing capacity, but it is a complicated construction method and is a relatively large scale because it involves inserting a reinforcing bar cage R. It can be said that it is assumed that foundation piles will be constructed.

An object of the present invention is to assume a small-scale foundation pile and to obtain a ground reinforcement method capable of constructing a concrete columnar reinforcing body capable of efficiently obtaining a large bearing capacity by simple construction.

In the ground reinforcement method of the invention according to claim 1, which solves the above-mentioned problems, the diameter D ₀ is 1.5 to 3.2 times the diameter d of the casing steel pipe on the tip surface of the casing steel pipe, and the central portion thereof.
The collar portion protruding from the outside the recess an end face plate having a recess formed in a circular contour of diameter D ₁ slightly concaved pile head side when viewed from below, cutout toward the center from the end surface plate periphery The end face plate is provided on both sides in the circumferential direction of the end face plate of the notch portion, in which inclined surface portions inclined in the opposite directions to each other are formed .
The engaging structure for detachably attaching the end face plate to the casing steel pipe has a protruding portion fixed to the outer peripheral surface of the lower end portion of the casing steel pipe in the longitudinal direction of the pipe and an arc plate portion along the outer peripheral surface of the casing steel pipe. It is composed of a joint member fixed to the upper surface of the end face plate, and the arc plate portion of the joint member enables the hook portion for engaging the protruding portion on the casing steel pipe side and the protruding portion from coming out. It has an opening to form a vacant space with an opening for accommodating the protruding portion, and the protruding portion engages with the vacant space with the opening by the hook portion when rotating in the rotational direction when the casing steel pipe is penetrated. , It is configured so that it can be pulled out from the vacant space with an opening at the opening in the reverse rotation.
The end face plate ,
The casing steel pipes mounted on the end face plates are rotationally penetrated into the ground and then into the casing steel pipes by engaging with each other in the rotational direction when the casing steel pipes are penetrated and detaching from each other in the opposite rotational direction. A concrete columnar reinforcing body is constructed by injecting a cement-based injection material for a pile body, then rotating the casing steel pipe in a direction opposite to the rotation direction at the time of penetration, and pulling out the casing steel pipe while leaving the end face plate. It is a feature.

A second aspect of the present invention is the ground reinforcement method of the first aspect, wherein an elongated member extending from the center side thereof toward the vicinity of the notch portion is welded and fixed to the concave portion of the end face plate.

According to a third aspect of the present invention, in the ground reinforcement method according to the first or second aspect, the end face plate is welded and fixed to the lower surface thereof, and is welded and fixed to the side end surface on the center side of the end face plate in the downwardly inclined inclined surface portion. It is characterized by having an inclined surface portion reinforcing member.

In the ground reinforcement method of the present invention, a cast-in-place concrete columnar reinforcing body is constructed by rotating a casing steel pipe into the ground, injecting a cement-based injection material for piles such as concrete, and then pulling out the casing steel pipe. It is a thing. Then, the end face plate detachably attached to the tip surface of the casing steel pipe is left in the ground when the casing steel pipe is pulled out after rotating through the casing steel pipe and injecting concrete or the like, and the lower end of the concrete columnar reinforcing body. Integrate as a part.
Since the diameter D ₀ of the end face plate in the present invention is significantly larger than the diameter d of the casing steel pipe, the concrete columnar reinforcing body constructed by this wide area end face plate integrated as the lower end portion of the concrete columnar reinforcing body. Can increase the bearing capacity of.
Further, since the end face plate of the present invention is a concave end face plate having a concave portion formed on the pile head side when viewed from the lower surface side, the contact surface with the ground works effectively when the soil is clogged in the concave portion. The bearing capacity of the constructed concrete columnar reinforcing body is higher than that of the case where the end face plate is a simple disk having a diameter.
As described above, the ground bearing capacity of the concrete columnar reinforcing body can be efficiently increased with a simple structure.
Further, since the concave end face plate is dented toward the pile head side when viewed from the lower surface side, the bending rigidity against the resistance received from the soil when penetrating into the ground becomes remarkably large. In the present invention, since the outer diameter of the end face plate is considerably large, if it is a flat plate, it may bend unless it is a sufficiently thick plate, but since the bending rigidity is large, it is necessary to unnecessarily increase the plate thickness. Absent.
Further, the protruding portion on the casing steel pipe side that engages with the open space of the joint member on the end face plate side is long in the longitudinal direction of the pipe, and the portion that receives the protruding portion is the arc plate portion of the joint member fixed to the end face plate. Therefore, it can receive a large force in the direction of rotation.
Further, with a simple structure, it is possible to obtain an engaging structure in which the distinction between the case where the casing steel pipe and the end face plate are brought into the engaged state and the case where the casing steel pipe is brought into the disengaged state becomes clear.

In claim 2, by welding and fixing an elongated member extending from the center side toward the vicinity of the notch portion in the recess on the back surface of the end face plate, it is possible to suppress an increase in resistance to excavation propulsion of the steel pipe pile. ..
That is, during rotational penetration, the downwardly inclined surface portion acts to enclose the excavated soil in the recess and push it in, but the recess on the back surface of the end face plate has an elongated member extending from the center side toward the vicinity of the notch. Since it exists as an excavation propulsion auxiliary bar, this elongated member acts to discharge the soil that is enclosed in the recess and pushed in from the notch. Therefore, it is suppressed that the soil is clogged too much in the recess during excavation propulsion, the resistance to the rotation of the downwardly inclined surface portion from the soil stuck in the recess is reduced, and the increase in the vertical resistance is also reduced.

Since the downward inclined surface portion receives a large resistance to the action of excavating the soil, the downward inclined surface portion may be deformed due to the large resistance. However, according to claim 3, the downward inclined surface portion ends via the inclined surface portion reinforcing member. Since it is connected to the face plate, the downward inclined surface portion is prevented from being deformed.

It is a front view of the casing steel pipe with an end face plate which is the state which the end face plate used in the ground reinforcement method of one Example of this invention is attached to the tip of the casing steel pipe. (A) is a plan view of the end face plate (end face plate with a joint member) in FIG. 1, and (b) is a front view of (a). 2A is a cross-sectional view taken along the line AA of FIG. 2A. It is a bottom view of the end face plate of FIG. 2 (a). (A) is an enlarged view of the main part seen from the direction of the arrow B in FIG. 2, and (b) is a view for explaining the joint portion (sand hatched portion) of the inclined surface portion reinforcing member in (a) with the downwardly inclined surface portion. .. In the process of manufacturing the end face plate, a state in which a notch is made in order to form an inclined surface portion in the disk is shown, and is a bottom view (a view corresponding to FIG. 4) of the disk. The joint portion for joining with the casing steel pipe in the end face plate of FIG. 2 is shown independently, and (a) is a front view of the joint portion (however, the hook portion on the back side is omitted). (B) is a cross-sectional view taken along the line CC of (a). The structure of the engagement between the casing steel pipe and the end face plate joint is explained. (A) is a front view of the engagement portion between the casing steel pipe and the end plate joint, and (b) is D- of (a). It is a D sectional view. Another embodiment of the joint portion of the end face plate with respect to the casing steel pipe is shown, (a) is a plan view of the end face plate with a joint member, and (b) is a front view of (a). Two joint members for joining with the casing steel pipe in the end face plate of FIG. 9 are shown independently, (a) is a front view of the joint member on the back side, and (b) is a plan view of (a). (C) is a front view of the joint member on the front side, and (d) is a plan view of (c). It is a figure explaining the construction procedure of the ground reinforcement construction method of this invention. It is a figure explaining an example of the aspect of constructing the foundation pile of a house by using the ground reinforcement method of this invention.

Hereinafter, a mode for carrying out the ground reinforcement method of the present invention will be described with reference to the drawings.

FIG. 1 is a front view of a casing steel pipe 11 with an end face plate in which the end face plate 3 used in the ground reinforcement method of one embodiment of the present invention is attached to the tip of the casing steel pipe 2, and FIG. 2 (a) is an end in FIG. A plan view of the face plate 3, FIG. 2 (b) is a front view of (a), FIG. 3 is a sectional view taken along the line AA of FIG. 2 (a), and FIG. 4 is a bottom view of the end face plate of FIG. 2 (a). ..
The end face plate 3 integrally fixes a joint member 12, which will be described in detail later, and is detachably attached to the tip of the casing steel pipe 2 via the joint member 12. The end plate 3, the ratio _D 0 / d of the diameter _{D 0} and the diameter d of the casing steel pipe 2 is 1.5 to 3.2, and preferably a _D 0 _/d=1.8~2.5, and the central portion, the recess 8 of the circular contour of diameter D ₁ slightly concaved pile head side as viewed from the lower surface side is formed.
The recess 8 in the illustrated example has a mortar shape. The circular contour of the recess 8 is shown by S in FIG. The outer portion (upper surface portion) of the recess 8 is indicated by 8'. The circular contour seen from above the outer portion 8'of the recess 8 is indicated by S'.
The flange portion 4 projecting outward from the recess 8 in the end face plate 3 has notches 5 extending from the peripheral edge of the end face plate 3 toward the center, and the notch portions 5 are provided on both sides of the end face plate in the circumferential direction. Inclined surface portions 6 and 7 (upward inclined surface portion 6 and downward inclined surface portion 7) inclined in the up-down direction are formed.
An elongated member 10 that functions as an excavation propulsion auxiliary bar extending from the center side of the recess 8 toward the vicinity of the notch 5 is welded and fixed to the recess 8. The elongated member 10 of the embodiment is a square bar (square member) having a square cross section of 18 mm in length and width and a length of 130 mm.

In this embodiment, an inclined surface portion reinforcing member 21 for reinforcing the downward inclined surface portion 7 is further welded and fixed to the lower surface of the end face plate 3.
The inclined surface portion reinforcing member 21 of the illustrated example is a square bar having a square cross section of 18 mm in length and width and a length of 40 mm, and as shown in FIG. 5 (a), the lower end thereof is the end face plate 3 and the end face plate in the downward inclined surface portion 7. It is welded and fixed so as to be in contact with the side end surface on the center side, and the upper side surface is welded and fixed to the side end surface on the end face plate center side of the downward inclined surface portion 7. The portion shown by the sand hatching in FIG. 5B is a region where the inclined surface portion reinforcing member 21 and the side end surface of the downward inclined surface portion 7 on the center side of the end face plate are joined. Welding is done around the area. In FIG. 2, the welded portion is indicated by Q.
The position where the inclined surface portion reinforcing member 21 of the illustrated example is fixed to the end face plate 3 is a flat portion between the circular contour S of the recess 8 and the arc-shaped notch m (see FIG. 6).
When the diameter of the end face plate 3 is small, the position of the inclined surface portion reinforcing member 21 may be the inclined surface of the recess 8, but in that case, the lower end surface of the inclined surface portion reinforcing member 21 is set to the inclined surface.

Regarding the dimensions of each part of the embodiment, the casing steel pipe 2 has a diameter d of 216.3 mm, a plate thickness of 5.3 mm or 8.2 mm, and a material STK400.
The end face plate 3 has a plate thickness T of 9 mm or 12 mm, a diameter D of 400 mm or 500 mm, and a recess 8 having a height H of 45 mm. The material is SS400 or SS490. The diameter of the circular contour S of the concave outer portion 8'is approximately 220 mm.

The method for producing the end face plate 3 is not particularly limited, but the inclined surface portions 6 and 7 may be formed after forming the recess 8 in the flat disk of the steel plate, or the inclined surface portions 6 and 7 may be formed in the flat disk. The recess 8 may be formed at the stage where a notch is made to form the recess 8. It is also conceivable to form a recess in a flat disk after making a notch and forming an inclined surface portion.
In FIG. 6, which is shown as a bottom view corresponding to FIG. 4, the case where the inclined surface portion is formed after the recess 8 is formed in the disk 9 is shown. In the figure, the end face plate at the stage before the inclined surface portion is formed is indicated by 3', and the portions to be the inclined surface portions 6 and 7 are indicated by 6'and 7'.
In the illustrated example, an arc-shaped cut m is made at a position slightly radially outside the circular contour S of the recess 8, and a cut n extending radially outward from the center position of the arc-shaped cut m is made, and then the cut is made. Both sides of n in the circumferential direction are inclined in the up-down directions to form inclined surface portions 6 and 7 in the up-down directions as shown in FIGS. 1, 2 (b) and 5. In FIG. 6, which is a bottom view, the valley fold portion when forming the inclined surface portions 6 and 7 is shown by a one-dot chain line, and the mountain fold portion is shown by a two-dot chain line.
Although it is related to the dimensional difference between the diameter D ₀ of the end face plate 3 and the diameter D ₁ of the circular contour S of the recess 8, the inclined surface portion reinforcing member is located between the arc-shaped notch m and the circular contour S. It is desirable to secure a flat space for welding and fixing the lower end of 21 to the end face plate 3.

The engagement structure for detachably attaching the end face plate 3 to the casing steel pipe 2 is also shown in FIGS. 1, 2 (b) and 3, but as shown in detail in FIGS. 7 and 8, the casing A tubular shape having a long protruding portion 14 in the longitudinal direction of the pipe fixed on both sides of the outer peripheral surface of the lower end portion of the steel pipe 2 in the radial direction and an arc plate portion 12a along the outer peripheral surface of the casing steel pipe and welded and fixed to the upper surface of the end face plate 3. The arc plate portion 12a of the joint member 12 comprises a hook portion 12c for engaging the protruding portion 14 on the casing steel pipe 2 side and an opening that allows the protruding portion 14 to come out. It is formed by forming an open space 12b having 14d. The end face plate with a joint member in which the engaging member 12 is welded and fixed to the end face plate 3 is indicated by reference numeral 15. In the case of the end face plate 3, the end face plate 15 with a joint member to which the joint member 12 is fixed and the end face plate 3 itself may be simply referred to as an end face plate.
As a result, the protruding portion 14 long in the longitudinal direction of the casing steel pipe 2 side is opened by the hook portion 12c in the rotation in the rotation direction (counterclockwise rotation in FIG. 8B) when the casing steel pipe is penetrated. Engage with the location 12b (protruding portion 14'in FIG. 8 (a) shown by the two-point chain line), and in the reverse rotation (clockwise rotation in FIG. 8 (b)), the solid line in FIG. 8 (a). At the position of the protruding portion 14 shown, the opening 12d can be pulled out from the open space 12b.
According to this structure, the protruding portion 14 on the casing steel pipe 2 side that engages with the open space 12b of the joint member 12 on the end face plate 3 side is long in the longitudinal direction of the pipe, and the portion that receives the protruding portion 14 is the end face plate. Since it is located on the arc plate portion 12a of the joint member 12 fixed to 3, it can receive a large force in the rotational direction.
Further, since the protruding portion 14 hits the wall surface 12f on the opening 12d side of the vacant space 12b with an opening when rotated in the clockwise direction, it is clear to distinguish between the case of engaging and the case of being able to pull out. As described above, with a simple structure, it is possible to obtain an engaging structure in which the case where the casing steel pipe 2 and the end face plate 3 are in the engaged state and the case where the casing steel pipe 3 is in the disengaged state are clearly distinguished.

11 (a) to 11 (d) are views for explaining the construction procedure of the ground reinforcement method according to the embodiment of the present invention, which is carried out using the above-mentioned casing steel pipe 2 and the end face plate 15 with a joint member.
The end face plate 3 (end face plate 15 with a joint member) is engaged with the lower end of the casing steel pipe 2 to form a casing steel pipe 11 with an end face plate as shown in FIG.
A rotary press-fitting drive unit 22 such as a pile driver is attached to the head of the casing steel pipe 11 with an end face plate as shown in FIG. 11 (a), and an end face plate is attached by the rotary press-fitting drive unit 22 as shown in FIG. The casing steel pipe 11 with a casing is rotationally penetrated into the ground to a predetermined depth.
Next, after removing the rotary press-fitting drive unit 22, a cement-based injection material for piles such as concrete, mortar, and aggregate-mixed cement milk, for example, concrete 23, is placed in the casing steel pipe 2 as shown in FIG. inject.
Next, the rotary press-fitting drive unit is attached to the head of the casing steel pipe 11 with an end face plate again, and the casing steel pipe 2 is pulled out as shown in FIG.
As a result, the concrete columnar reinforcing body 1 in which the end face plate 15 with a joint member is integrated with the lower end of the concrete column 23'is obtained.

Since the diameter D ₀ of the end face plate 3 in the concrete columnar reinforcing body 1 is significantly larger than the diameter d of the casing steel pipe, the end face plate 3 having a large area integrated as the lower end portion of the concrete columnar reinforcing body 1 is used. , The bearing capacity of the constructed concrete columnar reinforcing body 1 can be increased.
Further, since the end face plate 3 is a concave end face plate having a recess 8 formed on the pile head side when viewed from the lower surface side, the contact surface with the ground works effectively when the soil is clogged in the recess 8. The bearing capacity of the constructed concrete columnar reinforcing body 1 is higher than that of a simple end face plate of a disk having the same diameter.
As described above, the ground bearing capacity of the concrete columnar reinforcing body 1 can be efficiently increased with a simple structure.
Further, since the concave end face plate 3 is recessed toward the pile head side when viewed from the lower surface side, the bending rigidity against the resistance received from the soil when penetrating into the ground is remarkably large. Therefore, although the outer diameter of the end face plate 3 is considerably large and the resistance received from the soil is large, it is not necessary to unnecessarily increase the plate thickness.

Since the recess 8 is provided in the central portion of the end face plate 3, as described above, the contact surface with the ground works effectively because the recess 3 is clogged with soil when it penetrates the ground, and the bearing capacity can be reliably secured. However, in the case of rotary penetration, the resistance to excavation propulsion is a major factor because the soil is surrounded and pushed into the recess 8 especially at the downwardly inclined surface portion 7.
That is, if the soil is pushed too strongly into the recess 8 at the downwardly inclined surface portion 7 during the rotation penetration, the resistance to the rotation of the downwardly inclined surface portion 7 from the soil clogged in the recess 8 increases, and the resistance in the vertical direction also increases. Increase.
However, in the casing steel pipe 11 with the end face plate described above, since the elongated member 10 extending from the center side thereof toward the vicinity of the notch 5 is present in the recess 8 on the back surface of the end face plate 3, this elongated member 10 is present during excavation propulsion. The member 10 acts to discharge the soil that is enclosed in the recess 8 and pushed in. Therefore, it is suppressed that the soil is clogged too much in the recess 8, the resistance to the rotation of the downwardly inclined surface portion 7 from the soil clogged in the recess 8 is reduced, and the increase in the vertical resistance is also reduced. In this way, the elongated member 10 functions as an excavation propulsion auxiliary member.
The elongated member 10 of the embodiment is a square member having a square cross section, but is not limited to a square cross section but may be a rectangular cross section, and is not limited to a square member and may be a circular cross section or other cross section. Further, the member may have a plate-like shape having a height dimension significantly larger than a width dimension.
Further, the arrangement (position) of the elongated member 10 in the recess 8 is arranged and fixed so as to extend from the center side of the recess toward the vicinity of the notch 5, but when the end face plate 3 rotates and excavation is propelled. The behavior of the soil is complicated and is not strictly positioned. Therefore, it is possible to obtain an appropriate shape and arrangement of the elongated member by conducting experiments for various arrangements.

Further, since the downward inclined surface portion 7 receives a large resistance to the action of excavating the soil, the downward inclined surface portion 7 may be deformed due to the large resistance, but the downward inclined surface portion 7 passes through the inclined surface portion reinforcing member 21 and the end face plate 3 is used. Since it is connected to, the downward inclined surface portion 7 is prevented from being deformed.

9 and 10 show the joint member 12'of another embodiment with respect to the casing steel pipe 2 of the end face plate 3. 9 (a) is a plan view of an end face plate (end face plate 15'with a joint member) provided with a joint member 12', and FIG. 9 (b) is a front view of (a). 10 is a front view of the joint member 12'on the back side of FIG. 9, (b) is a plan view of (a), (c) is a front view of the joint member 12'on the front side, and (d) is (c). It is a plan view of.
As shown in FIGS. 1 to 3, 7, 8 and the like, the joint member 12 in the above-described embodiment has a tubular shape that covers the outer periphery of the casing steel pipe 2, and is an arc plate along the outer peripheral surface of the casing steel pipe. Although the portions 12a are formed on both sides in the radial direction of the cylinder, the joint member 12'of this embodiment is the empty space 12b with two openings on both sides in the radial direction of the tubular joint member 12 described above. The vicinity (arc plate portion 12a) is welded and fixed to the end face plate 3 as separate joint members 12'.
That is, in the joint member 12'of this embodiment, the vicinity (arc plate portion 12a) of the two open spaces 12b in the joint member 12 of the above-described embodiment is a single joint member 12'. is there. The space 12b with an opening, the hook portion 12c, and the opening 12d of the joint member 12'are the same as those of the joint member 12 of the above-described embodiment.

FIG. 12 simply shows an example of constructing a concrete columnar reinforcing body 1 as a pile supporting the foundation concrete 20 of a building such as a house by the ground reinforcement method described with reference to FIG.
According to the concrete columnar reinforcing body 1 according to the present invention, the ground bearing capacity is improved, so that a desired bearing capacity can be secured with a smaller number of piles (concrete columnar reinforcing body 1) than before.
Further, when the casing steel pipe 11 with an end face plate is penetrated into the ground, as described above, the elongated member 10 fixed to the lower surface of the end face plate 3 reduces the resistance of the end face plate 3 to the excavation propulsion.

1 Concrete columnar reinforcing body 2 Casing steel pipe 3 End face plate 3'End face plate at the stage before the inclined surface portion is formed 4 Flange 5 Notch portion 6 Upward inclined surface portion 6'Upward inclined surface portion 7 Downward inclined surface portion 7 'Part that becomes a downwardly inclined surface part 8 Recess 8'Outer part of the recess 10 Elongated member (excavation propulsion auxiliary bar)
11 Casing steel pipe with end face plate 12. 12'Joint member 12a Arc plate part 12b Vacancy with opening 12c Hook part 12d Opening 14 Protruding part 15 End face plate with joint member 21 Inclined surface reinforcement member S Circular contour of recess S'Outside of recess Circular contour T (of end face plate) seen from above d Diameter of casing steel pipe D ₀ Diameter of end face plate D ₁ Diameter of circular contour of recess H Height of recess

Claims (3)

On the tip surface of the casing steel pipe, the diameter D ₀ is 1.5 to 3.2 times the diameter d of the casing steel pipe, and at the center.
The collar portion protruding from the outside the recess an end face plate having a recess formed in a circular contour of diameter D ₁ slightly concaved pile head side when viewed from below, cutout toward the center from the end surface plate periphery The end face plate is provided on both sides in the circumferential direction of the end face plate of the notch portion, in which inclined surface portions inclined in the opposite directions to each other are formed .
The engaging structure for detachably attaching the end face plate to the casing steel pipe has a protruding portion fixed to the outer peripheral surface of the lower end portion of the casing steel pipe in the longitudinal direction of the pipe and an arc plate portion along the outer peripheral surface of the casing steel pipe. It is composed of a joint member fixed to the upper surface of the end face plate, and the arc plate portion of the joint member enables a hook portion for engaging the protruding portion on the casing steel pipe side with the arc plate portion and the protruding portion from coming out. It has an opening to form a vacant space with an opening for accommodating the protruding portion, and the protruding portion engages with the vacant space with the opening by the hook portion when rotating in the rotational direction when the casing steel pipe is penetrated. , It is configured so that it can be pulled out from the vacant space with an opening at the opening in the reverse rotation.
The end face plate ,
The casing steel pipes mounted on the end face plates are rotationally penetrated into the ground and then into the casing steel pipes by engaging with each other in the rotational direction when the casing steel pipes are penetrated and detaching from each other in the opposite rotational direction. A concrete columnar reinforcing body is constructed by injecting a cement-based injection material for a pile body, then rotating the casing steel pipe in a direction opposite to the rotation direction at the time of penetration, and pulling out the casing steel pipe while leaving the end face plate. The characteristic ground reinforcement method. The ground reinforcement method according to claim 1, wherein an elongated member extending from the center side of the end face plate toward the vicinity of the notch portion is welded and fixed to the recess. Claim 1 or 2 is characterized in that the end face plate is welded and fixed to the lower surface thereof, and has an inclined surface portion reinforcing member welded and fixed to the side end surface on the end face plate center side in the downwardly inclined inclined surface portion. The described ground reinforcement method.

Images