JP2016006264A - Ground improvement pile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a ground improvement pile having further stable bearing capacity.SOLUTION: In a ground improvement pile 100 having a solidified improvement body 10 arranged in a drilling hole H which is vertical to the ground G, and a core material 20 embedded into the solidified improvement body 10, the core material 20 comprises: bar steel 24 which extends along an axial core of the solidified improvement body 10; a plurality of first reinforcements 21 which are wound around the bar steel 24 so as to hang out toward one direction (X-direction) which intersects with an extension direction of the bar steel 24, and in which points which line-contact with a part of a peripheral face of the bar steel 24 are welded; and a plurality of second reinforcements 22 which intersect with the extension direction of the bar steel 24, are wound around the surroundings of the bar steel 24 so as to hang out toward the other direction (Y-direction) which intersects with one direction, and welded to at least a part of the peripheral face of the bar steel 24. The first reinforcement 21 and the second reinforcements 22 are alternately arranged in the extension direction of the bar steel 24.

Description

  The present invention relates to a ground improved pile that enhances the bearing capacity of the pile.

Conventionally, it is formed by building a core material that has a structure in which reinforcing bars are wrapped around steel bars in an improved body made of soil cement formed by mixing earth and sand and cement milk in a drilling hole drilled vertically in the ground. There is an invention related to a ground improvement pile (see, for example, Patent Document 1).
In this invention, the reinforcing bar wound spirally around the steel bar is provided in order to increase the adhesion between the steel bar and the improved body, and to enhance the supporting force of the ground improvement pile.

JP-A-6-116947

However, in the case of the above-mentioned Patent Document 1, since the steel bar and the reinforcing bar are in point contact and only a portion where the contact area is small is welded, the core material is inserted so as to be embedded in the improved body. In this case, there is a problem that the welded portion is easily broken.
And, for example, when the joint strength of the welded part has not been secured, if breakage occurs at many of the welded parts, the adhesion between the core material and the improved body is reduced, and the ground improvement pile is supported. There was a risk that the power would decrease.

  An object of the present invention is to provide a ground improvement pile having a more stable supporting force.

In order to achieve the above object, the present invention provides:
A ground improvement pile having a solidified improvement body provided in a drilling hole formed in a vertical direction on the ground, and a core material embedded in the solidification improvement body,
The core material is
A steel bar extending along the axis of the solidified body,
A plurality of first reinforcing bars wound around the steel bar so as to project in one direction intersecting with the extending direction of the steel bar, and welded at at least a part of the circumferential surface of the steel bar to be in line contact; ,
A plurality of second reinforcing bars that are wound around at least a part of the circumferential surface of the steel bar and are wound around the steel bar so as to extend in a direction crossing the extending direction of the steel bar and crossing the one direction. When,
With
The first reinforcing bar and the second reinforcing bar are respectively arranged at an arbitrary interval in the extending direction of the steel bar.

According to such a configuration, a plurality of first rebars welded so as to project in one direction and a plurality of second rebars welded so as to project in the other direction are formed on the core of the core material of the ground improvement pile. Reinforcing bars are provided, and the first reinforcing bar and the second reinforcing bar are arranged, for example, alternately at an arbitrary interval in the extending direction of the bar steel, so that the core material embedded in the solidified improvement body is solidified. It is easy to integrate with the improved body.
In other words, the ground improvement pile having such a configuration can improve the adhesion between the core material and the solidified improvement body, stabilize the integrated structure of the core material and the solidification improvement body, and has a more stable support force. The function as an improved pile can be demonstrated.
In particular, the first rebar and the second rebar, which are arranged to cross each other, are welded at a location where the first rebar is in line contact with a part of the peripheral surface of the bar steel and fixed to the bar steel relatively firmly. Since all the rebars welded to (1st rebar, 2nd rebar) are not broken, at least the first rebar is kept fixed to the peripheral surface of the steel bar. The integrated structure of the solidified improvement body can be stabilized.

Also, preferably
The first reinforcing bar and the second reinforcing bar are provided at a narrower distance toward the lower end side of the strip.
The ground improvement pile having a core material provided with more first and second reinforcing bars on the lower end side of the steel bar functions as a support structure having a strong tip supporting force.

Also, preferably
The first reinforcing bar and the second reinforcing bar are arranged in contact with each other, and the first reinforcing bar is disposed on the upper side of the second reinforcing bar.
The first rebar is welded at a point in line contact with at least a part of the peripheral surface of the bar steel, and is stronger than the second rebar where, for example, a point contact is welded to at least a part of the peripheral surface of the bar steel. Since the first rebar and the second rebar are in contact with each other and the first rebar is positioned on the upper side, the first rebar is inserted into the solidified improved body. The rebar can support the second rebar, and the breakage of the welded portion of the second rebar can be reduced.

Also, preferably
A reinforcing member welded to the peripheral surface of the bar steel is provided at a location where the first reinforcing bar is welded to the peripheral surface of the bar steel and arranged in contact with the upper side of the first reinforcing bar.
The first reinforcing bar can be reinforced by the reinforcing member welded to the circumferential surface of the bar steel so as to be in contact with the first reinforcing bar. And the fracture | rupture of the welding part of a steel bar, a 1st reinforcing bar, and a 2nd reinforcing bar can further be reduced by this reinforcement member.

Also, preferably
The core material is provided inside the excavation hole so that the solidified improvement body is interposed around the core material and between the bottom portion of the excavation hole and the lower end portion of the bar steel. To.
In this way, the solidified improved body is interposed between the bottom of the excavation hole and the lower end of the steel bar, so that even if the lower layer of the ground is weak, the core material of the ground improved pile will be lowered. Such a situation can be prevented, and the integrated structure of the core material and the solidified improved body becomes stable.

  According to the present invention, a ground improvement pile having a more stable supporting force can be obtained.

It is explanatory drawing (a) which looked at the ground improvement pile of this embodiment from the side, and explanatory drawing (b) which looked at the ground improvement pile of the direction from the top. It is explanatory drawing (a) which looked at the ground improvement pile of this embodiment from the other side, and explanatory drawing (b) which looked at the ground improvement pile of the direction from the top. It is a perspective view for demonstrating the direction of the 1st reinforcing bar and the 2nd reinforcing bar in the core material of a ground improvement pile. It is a side view which shows an example of the core material of a ground improvement pile. It is explanatory drawing regarding the construction method of a ground improvement pile, and has shown the solidification improvement body formation process (a), the core material embedding process (b), and the curing process (c). It is explanatory drawing regarding the test for confirming the adhesive force of the core material and solidification improvement body in a ground improvement pile, the test body (a) of "CASE-I", the test body (b) of "CASE-II" , "CASE-III" specimen (c). It is a diagram which shows the measurement result of the adhesion confirmation test of the core material and solidification improvement body in a ground improvement pile. It is a diagram which shows the measurement result of the vertical loading test done with respect to the ground improvement pile. It is a perspective view which shows the modification of the core material of a ground improvement pile.

  Hereinafter, an embodiment of a ground improvement pile according to the present invention will be described in detail with reference to the drawings. However, the embodiments described below are given various technically preferable limitations for carrying out the present invention, but the scope of the present invention is not limited to the following embodiments and illustrated examples.

Fig.1 (a) is explanatory drawing which looked at the ground improvement pile 100 from the side, and FIG.1 (b) is explanatory drawing which looked at the ground improvement pile 100 of the direction from the top. FIG. 2A is an explanatory view of the ground improvement pile 100 viewed from the other side, and FIG. 2B is an explanatory view of the ground improvement pile 100 in the direction as viewed from above.
As shown in FIG. 1 and FIG. 2, the ground improvement pile 100 includes a solidified improvement body 10 provided in an excavation hole H oriented in a direction perpendicular to the ground G, and a core material 20 embedded in the solidification improvement body 10. ,have. The ground improvement pile 100 is a support constructed to support the construction girder in a construction site requiring a construction girder, for example, when a structure is newly installed under a railway track.
In addition, in the figure, in order to make the arrangement | positioning of the core material 20 in the ground improvement pile 100 easy to visually recognize, it has illustrated in the state which saw through the solidification improvement body 10. FIG.

The solidified improvement body 10 is a columnar body obtained by mixing earth and sand from which the ground G has been cut and a solidified material such as cement slurry in the ground to solidify it, and is embedded in the ground G in a vertical direction. .
For example, the solidification improving body 10 is formed so that the solidification material is injected into the excavation hole H while excavating the ground G, and the range in which the earth and sand and the solidification material are mixed and stirred is expanded in the vertical direction. In this embodiment, the columnar solidification improving body 10 having a diameter of 800 mm is formed and used.

The core material 20 includes a steel bar 24 extending along the axis of the solidified improved body 10, a first reinforcing bar 21 provided so as to project in one direction orthogonal to the extending direction of the steel bar 24, and a steel bar 24. And a second rebar 22 provided so as to project in the other direction perpendicular to the extending direction and intersecting one direction.
The core member 20 is provided with a plurality of first reinforcing bars 21 and a plurality of second reinforcing bars 22, and the first reinforcing bars 21 and the second reinforcing bars 22 are alternately arranged in the extending direction of the steel bar 24. Yes. Further, the first reinforcing bar 21 and the second reinforcing bar 22 are disposed so as to protrude from the bar steel 24 in directions orthogonal to each other.
The first rebar 21 and the second rebar 22 are provided at a high density at a narrower distance toward the lower end side of the bar 24.

The steel bar 24 is, for example, an H-section steel, and in the present embodiment, an “H-350 × 350 × 12 × 19” H-section steel is used. The bar 24 protrudes from the solidified improvement body 10 on the upper end side of the ground improvement pile 100 and is provided in an exposed state.
The long bar 24 can be formed to a desired length by connecting a plurality of H-shaped steels via a joint T (see FIG. 4).

The first reinforcing bar 21 and the second reinforcing bar 22 are substantially rectangular frame-like members formed by bending a reinforcing bar “D13” and welding both ends, for example.
As shown in FIG. 3, when the extending direction (vertical direction) of the bar 24 is the Z-axis direction, the first reinforcing bar 21 has both sides of the first reinforcing bar 21 extending from the bar 24 to the X-axis direction (one direction). A reinforcing bar “D13” is wound around the bar 24 so as to project. And the location where the 1st rebar 21 was in line contact with at least a part of the peripheral surface of the bar steel 24, here, the location where the line contact was made on the outer surface of the flange of the H section steel, was welded, and the 1st rebar 21 was fixed to the bar 24 Has been.
As shown in FIG. 3, when the extending direction (vertical direction) of the steel bar 24 is the Z-axis direction, the second reinforcing bar 22 has both sides of the second steel bar 22 extending from the steel bar 24 to the Y-axis direction (other directions). A reinforcing bar “D13” is wound around the bar 24 so as to project. And the location where the 2nd reinforcement 22 contacted at least one part of the surrounding surface of the bar steel 24, the point contacted to the edge part of the flange of H-section steel here is welded, and the 2nd reinforcement 22 is fixed to the bar 24 Has been.

In particular, the first reinforcing bar 21 and the second reinforcing bar 22 are arranged so as to contact each other, and the first reinforcing bar 21 is disposed above the second reinforcing bar 22.
Here, the first rebar 21 is welded at the point where line contact is made with the outer surface of the flange of the H-shaped steel which is the bar 24, and is welded at the point where point contact is made with the end of the flange of the H-shaped steel. Since the first reinforcing bar 21 and the second reinforcing bar 22 are in contact with each other, the first reinforcing bar 21 can support the second reinforcing bar 22 because the first reinforcing bar 21 and the second reinforcing bar 22 are in contact with each other. To.
In the present embodiment, since the first rebar 21 is disposed above the second rebar 22, for example, when the core material 20 is embedded in the solidified improvement body 10, the second rebar 22 is raised by the first rebar 21. Can be prevented, and breakage of the welded portion of the second rebar 22 can be reduced.

Furthermore, the reinforcement which was welded to the peripheral surface (the outer surface of the flange of H-section steel) of the bar steel 24 by the arrangement | positioning which contacts the upper side of the 1st reinforcing bar 21 in the location where the 1st reinforcing bar 21 was welded to the peripheral surface of the bar steel 24 A member 23 is provided. The reinforcing member 23 is a plate-like member in which, for example, an iron plate or a steel plate is formed in a predetermined size.
For example, the first reinforcing bar 21 welded to the peripheral surface of the bar 24 can be reinforced by welding the pair of left and right reinforcing members 23 to the peripheral surface of the bar 24. By this reinforcement, breakage of the welded portion of the first reinforcing bar 21 and the second reinforcing bar 22 can be further reduced.

And in the ground improvement pile 100 of this embodiment, the reinforcement reinforcing-bar assembly 30 comprised by the 1st reinforcing bar 21, the 2nd reinforcing bar 22, and the reinforcing member 23 welded to the strip 24 can be grasped | ascertained as one structure. .
The core material 20 of the ground improvement pile 100 shown in FIGS. 1 and 2 is provided with five steps (five sets) of reinforcing bar assemblies 30 on the lower end side of the steel bar 24, and two steps ( 2 sets) of reinforcing steel bar assemblies 30 are provided.
The length of the ground improvement pile 100 and the number of steps of the reinforcing reinforcing bar assembly 30 are arbitrary. For example, as shown in FIG. 4, five reinforcing reinforcing bar assemblies 30 are provided at intervals of 200 mm on the lower end side of the bar 24, The ground improvement pile 100 having a desired length can be created by assembling the core material 20 so as to provide the two-stage reinforcing bar assembly 30 at intervals of 500 mm every 1000 mm above the strip 24.

Moreover, the ground improvement pile 100 of this embodiment is provided with the solidification improvement body 10 so that the circumference | surroundings of the core material 20 may be covered, and it is especially solidified between the bottom part of the excavation hole H, and the lower end part of the bar 24. The core material 20 is disposed with the improved body 10 interposed.
By interposing the solidified improvement body 10 between the bottom part of the excavation hole H and the lower end part of the bar steel 24, it is possible to prevent the core material 20 of the ground improvement pile 100 from being lowered. 20 and the solidification improving body 10 are improved in adhesion, and the integral structure of the core material 20 and the solidification improving body 10 becomes stable.
For example, when the lower end of the bar 24 is exposed or protrudes from the lower surface of the solidified improved body 10, the load such as the weight of the construction beam supported by the bar 24 on the upper end of the ground improvement pile 100 is compared. It is easy to move so as to concentrate on the narrow bar 24 and the bar 24 enters the ground G. If the steel bar 24 moves so as to enter the ground G, the integrated structure of the core material 20 and the solidified improved body 10 may be broken, and the strength of the ground improved pile 100 may be reduced. Therefore, the solidification improvement body 10 is interposed between the bottom part of the excavation hole H and the lower end part of the steel bar 24 to restrict the movement of only the core material 20, and the load applied to the steel bar 24 is improved by a relatively wide solidification. The lower surface of the body 10 is transmitted to the ground G.

  Next, the construction method of the ground improvement pile 100 is demonstrated based on FIG.

First, the columnar solidified improvement body 10 is formed in the ground by a well-known mechanical stirring / high pressure injection combined method (mechano jet method) or the like.
Specifically, the injection pipe 1 of the solidifying material pump (not shown) installed on the ground G is rotated and the ground G is cut by the excavation bit 2 provided at the tip of the injection pipe 1 while the injection pipe 1 is cut. Is inserted vertically into the ground. In addition, since the solidification material pump is the same as a well-known thing, it does not elaborate here.
After the excavation bit 2 reaches a predetermined depth and forms an excavation hole H oriented in the vertical direction on the ground G, the injection pipe 1 is gradually pulled up while being reversely rotated, as shown in FIG. At that time, the solidified material is supplied from the injection port of the excavation bit 2 by supplying the solidified material through the injection pipe 1, and the solidification material and earth and sand are excavated by the stirring blades provided in the injection pipe 1 and the excavation bit 2. Mix and stir in H. In this way, the solidified improvement body 10 is formed vertically from the bottom to the top. Instead of releasing the solidifying material when the injection tube 1 is pulled up from the ground, the solidifying material may be discharged when the injection tube 1 is inserted into the ground.

  Next, as shown in FIG. 5 (b), while the solidified improvement body 10 formed in the excavation hole H has fluidity, the first rebar 21, the second rebar 22, and the reinforcing member are added to the bar steel 24. The core material 20 assembled by welding 23 is embedded in the solidified improved body 10 in the vertical direction.

Next, as shown in FIG. 5 (c), curing is performed such that the solidification improving body 10 is interposed between the bottom of the excavation hole H and the lower end of the steel bar 24 of the core member 20 for a predetermined time. The solidification improving body 10 which is a mixture of the solidification material and earth and sand is solidified (cured). The solidified improvement body 10 cured by this curing has rigidity, and a ground improvement pile 100 embedded in the ground in the vertical direction is created.
In addition, the thickness of the solidification improvement body 10 interposed between the bottom part of the excavation hole H and the lower end part of the bar steel 24 of the core material 20 is arbitrary, and depends on the length of the ground improvement pile 100, the strength of the ground G, or the like. What is necessary is just to adjust suitably.

  Next, the test performed in order to confirm the adhesive force of the core material 20 and the solidification improvement body 10 in the ground improvement pile 100 of this embodiment is demonstrated.

As shown in FIG. 6, the test body of the ground improvement pile 100 was installed on the iron plate P of 30 mm in thickness and 900 mm square mounted on the test stand, and the adhesive force confirmation test was done. The iron plate P is formed with a substantially H-shaped through hole Q into which the H-shaped steel of the test body can be inserted.
FIG. 6A shows a test body of the test “CASE-I”. The “CASE-I” test body is a test body for a comparative test in which a bar 1400 mm in length is embedded in a solidified improved body 10 having a diameter of 800 mm and a height of 1000 mm.
FIG. 6B shows a test body of the test “CASE-II”. The “CASE-II” test specimen is embedded in a solidified improved body 10 having a diameter of 800 mm and a height of 1000 mm, and a core material 20 in which a five-stage reinforcing bar assembly 30 is provided below a 1400 mm long steel bar 24. This is a test body.
FIG. 6C shows a test body of the test “CASE-III”. The “CASE-III” test body is embedded in the solidified improved body 10 having a diameter of 800 mm and a height of 1000 mm, in which a core material 20 in which a three-stage reinforcing bar assembly 30 is provided at the bottom of a 1400 mm long bar 24 This is a test body.
In addition, the solidification improvement body 10 of this test body mixes solidification material "Mjet-2" with washing sand with the addition amount 600 [kg / m < ³ >], and a water cement ratio (W / C) 80 [%]. It is adjusted. Further, the H-shaped steel of “H−350 × 350 × 12 × 19” was used for the bar 24, and the first reinforcing bar 21 and the second reinforcing bar 22 of the reinforcing reinforcing bar assembly 30 were made of “D13” reinforcing bars.

A test is performed in which the jack J (in this case, 7000 kN jack) is pressed against the upper end of the core 20 (strip 24) of the test body as described above, and loaded in a stepwise manner in the vertical direction. ) And the load of the jack J were obtained. The test results are shown in FIG. 7, the measurement results of CASE-I are shown by the broken line L1 in FIG. 7, the measurement results of CASE-II are shown by the broken line L2 in FIG. 7, and the measurement results of CASE-III are shown by the broken line L3 in FIG.
As shown in FIG. 7, the maximum load on the CASE-I specimen (without the reinforcing reinforcing bar assembly 30 and the unreinforced steel bar 24) is 1207 [kN], whereas the CASE-II specimen ( The maximum load of the reinforcing steel bar assembly 30 (5 steps / m) was 6506 [kN], and the maximum load of the CASE-III specimen (reinforcing steel bar assembly 30; 3 steps / m) was 2874 [kN]. In addition, the measurement with respect to the test body of CASE-II was completed when the maximum loadable load was reached.
Thus, since the maximum load of CASE-II and CASE-III is larger than CASE-I, the adhesion strength between the core material 20 and the solidified improvement body 10 is increased by the reinforcing reinforcing bar assembly 30. I understand. Moreover, since the value of CASE-II is larger than CASE-III, it turns out that the number of steps of the reinforcing steel bar assembly 30 contributes to an increase in adhesion.

Next, the vertical loading test performed with respect to the ground improvement pile 100 of this embodiment is demonstrated.
Here, test piles No. 1 with different penetration depths are used. 1 and test pile No. 1 2 was prepared and a vertical loading test was performed.
Test pile No. 1 is a “CASE-II” type ground improvement pile 100 having a core member 20 provided with a five-stage reinforcing bar assembly 30 on the lower end side of a steel bar 24 having a length of 9 m and a solidified improvement member 10 having a diameter of 800 mm. Yes, the reinforcing reinforcing bar assembly 30 part reaches the sandy soil layer in the ground.
Test pile No. 2 is a “CASE-II” type ground improvement pile having a core material 20 provided with a five-stage reinforcing bar assembly 30 on the lower end side of a 11.5 m long steel bar 24 and a solidified improvement body 10 having a diameter of 800 mm. 100, and the reinforcing reinforcing bar assembly 30 portion reaches the gravel layer in the ground.
In this test, the soil surface (0m) to 7.45m in the ground is a viscous soil layer, 7.45m to 10.15m is a sandy soil layer, 10.15m to 12.45m is a gravel layer. The test ground was constructed on the ground.
Further, the steel bar 24 of the ground improvement pile 100 uses an H-shaped steel of “H-350 × 350 × 12 × 19”, and the first reinforcing bar 21 and the second reinforcing bar 22 of the reinforcing reinforcing bar assembly 30 are reinforcing bars of “D13”. Was used.

The test piles (No.1, No.2) embedded in the ground as described above are subjected to a test in which the load is intermittently applied in the vertical direction, and the relationship between the pile head displacement of the test pile and the load, and the test pile The relationship between the pile tip displacement and the load was obtained.
The test results are shown in FIG. Test pile No. No. 1 pile head displacement amount and the load are correlated with the broken line Lt in FIG. The correlation between the pile tip displacement amount of 1 and the load is shown by a broken line Ld in FIG. In addition, test pile No. 2 shows the correlation between the pile head displacement and the load, with the broken line Lt in FIG. The correlation between the pile tip displacement amount and the load of No. 2 is shown by a broken line Ld in FIG.

As shown to Fig.8 (a), test pile No. which has the solidification improvement body 10 of diameter 800mm (= D). The second limit resistance force of 1 was 2837 [kN] at a point where the displacement amount was 0.1D (= 80 mm). On the other hand, the test pile No. based on the railway standard formula which is a predetermined calculation formula. The ultimate vertical supporting force L of 1 was 1462 [kN]. Thus, test pile No. 1 has a second limit resistance force (2837 [kN]) that is greater than the ultimate vertical support force (1462 [kN]) according to the railway standard formula, the peripheral support force (peripheral friction force) of the solidified improved body 10 Test pile No. It can be seen that this contributes favorably as the supporting force of 1.
Moreover, as shown in FIG.8 (b), test pile No. which has the solidification improvement body 10 of diameter 800mm (= D). The second limit resistance force No. 2 was 5500 [kN] at a point where the displacement amount was 0.1 D (= 80 mm). On the other hand, the test pile No. based on the railway standard formula which is a predetermined calculation formula. The ultimate vertical supporting force L of 2 was 3008 [kN]. Thus, test pile No. The second limit resistance force (5500 [kN]) of No. 2 is larger than the ultimate vertical support force (3008 [kN]) according to the railway standard formula, so the peripheral surface support force (peripheral friction force) of the solidified body 10 is improved. Test pile No. It can be seen that it contributes suitably as the support force of No. 2.
That is, as the adhesion force between the core material 20 and the solidified improved body 10 is increased by the reinforcing reinforcing bar assembly 30, the peripheral surface supporting force of the solidified improved body 10 preferably contributes as the supporting force of the ground improved pile 100. Thus, the ground improvement pile 100 can secure a supporting force according to the cross-sectional size of the solidified improvement body 10 including the bar steel 24.

As mentioned above, the ground improvement pile 100 of this embodiment has the core material 20 provided with the 1st reinforcing bar 21 and the 2nd reinforcing bar 22 which were welded to the steel bar 24 by the arrangement | positioning which mutually contacted, The 1st Since the location where the 1 rebar 21 is in line contact with the bar 24 is welded, the first rebar 21 firmly fixed to the bar 24 can support the second rebar 22 so as to reinforce it.
That is, among the first rebar 21 and the second rebar 22 that are welded to the steel bar 24 in an arrangement in contact with each other, the first rebar 21 is welded and fixed firmly at a location where the first rebar 21 is in line contact with the steel bar 24. Further, it is possible to reduce the breakage of the welded portion of the steel bar 24, the first reinforcing bar 21, and the second reinforcing bar 22.
Further, the first reinforcing bar 21 can be reinforced by the reinforcing member 23 welded to the peripheral surface of the bar steel 24 so as to contact the first reinforcing bar 21, and the bar 24, the first reinforcing bar 21, and the second reinforcing bar can be reinforced by the reinforcing member 23. The breakage of the welded portion with 22 can be further reduced.

  Thus, if the 1st rebar 21 and the 2nd rebar 22 are the ground improvement pile 100 which has the core material 20 which is hard to fracture | rupture from the strip 24, the adhesive force of the core material 20 and the solidification improvement body 10 has a strong state. Since it can maintain, the ground improvement pile 100 which improved the durability can be functioned as a support body which has a more stable support force, and can be used conveniently.

The first reinforcing bar 21 and the second reinforcing bar 22 (or the reinforcing reinforcing bar assembly 30 including the first reinforcing bar 21 and the second reinforcing bar 22) increases the adhesion force between the core material 20 and the solidified improvement body 10, thereby solidifying. The peripheral surface supporting force of the improved body 10 preferably contributes as the supporting force of the ground improved pile 100, and the ground improved pile 100 has a supporting force corresponding to the cross-sectional size of the solidified improved body 10 including the bar steel 24. It is possible to secure.
Moreover, since the ground improvement pile 100 is equipped with many 1st reinforcing bars 21 and 2nd reinforcing bars 22 (or the reinforcement reinforcing bar assembly 30 containing the 1st reinforcing bar 21 and the 2nd reinforcing bar 22) by the lower end side of the bar 24, It can function as a support having a strong tip support force.
In other words, the ground improvement pile 100 including the core material 20 and the solidified improvement body 10 integrated with a strong adhesion force has both a peripheral surface support force and a tip support force, and a support body having a well increased support force. Therefore, for example, it is possible to shorten the pile length (rooting length) as compared with the case of constructing a support body that supports a construction girder using a steel pipe pile.

The present invention is not limited to the above embodiment.
In the ground improvement pile 100 of the said embodiment, although the 1st reinforcing bar 21 and the 2nd reinforcing bar 22 were welded to the steel bar 24 by the arrangement | positioning which mutually contacted, for example, as shown in FIG. The ground improvement pile 100 using the core material 20 in which the reinforcing bars 22 are separated and are welded to the bar 24 in an arrangement with an arbitrary interval in the extending direction of the bar 24 may be used.

  As shown in FIG. 9, the first rebar 21 protruding from the bar 24 in the X-axis direction is in contact with the peripheral surface of the bar 24 and welded to the upper side of the first rebar 21. A reinforcing member 25 having a size substantially the same as the width of the flange of the H-shaped steel may be welded to the peripheral surface of the bar steel 24 to reinforce the welded portion of the first rebar 21.

Further, as shown in FIG. 9, the second rebar 22 protruding from the bar 24 in the Y-axis direction is welded in a point contact with the bar 24, and is arranged in contact with the upper side of the second rebar 22. A reinforcing member 26 having a U-shape, which is attached in a line contact with the flange of the H-shaped steel by sandwiching the end of the flange of the shaped steel, is welded to the steel bar 24 to reinforce the welded portion of the second rebar 22. Also good.
Similarly, as shown in FIG. 9, the second rebar 22 protruding from the bar 24 in the Y-axis direction is welded in point contact with the bar 24 and the second rebar 22 is sandwiched between the flanges of the H-section steel. A reinforcing member 27 having a U shape that is attached in line contact with the outer surface of the steel bar may be welded to the steel bar 24 to reinforce the welded portion of the second rebar 22.
The U-shaped reinforcing member 26 and the reinforcing member 27 can be formed by bending a reinforcing bar “D13” into a U shape.

  Further, as shown in FIG. 9, the welded portion of the first rebar 21 may be reinforced by using a reinforcing member 26 that sandwiches the end of the H-shaped steel flange and makes line contact with the H-shaped steel flange. .

  In the above embodiment, the first reinforcing bar 21 and the second reinforcing bar 22 are frame-shaped members having a substantially rectangular shape, but the present invention is not limited to this, for example, The first rebar 21 and the second rebar 22 having a substantially oval shape composed of a semicircle and a straight line may be used, and the shape of the portion where the first rebar 21 and the second rebar 22 project from the bar steel 24 is arbitrary. is there.

In the above embodiment, the first rebar 21 and the second rebar 22 are arranged so that they are in contact with each other, and the first rebar 21 is disposed above the second rebar 22. It is not limited to this, You may arrange | position so that the 1st reinforcing bar 21 and the 2nd reinforcing bar 22 may contact each other, and the 2nd reinforcing bar 22 may be located above the 1st reinforcing bar 21. FIG.
In addition, the reinforcing member 23 is fixed to the arrangement in contact with the lower side of the first reinforcing bar 21 without being limited to welding and fixing the reinforcing member 23 to the peripheral surface of the bar 24 in the arrangement in contact with the upper side of the first reinforcing bar 21. You may make it do.
The upper and lower positional relationship of the first reinforcing bar 21, the second reinforcing bar 22, and the reinforcing member 23 depends on the effect and purpose of reinforcing each other, the direction of the load acting on the first reinforcing bar 21 and the second reinforcing bar 22, and the like. What is necessary is just to change suitably.

  Further, in the above embodiment, the H-section steel is used as the strip 24, but the present invention is not limited to this, and for example, the cross-section T-section, the cross-section L-section, Any steel bar can be used as long as it is capable of welding the first rebar 21 in line contact, such as a U-shaped steel bar.

  In addition, it is needless to say that other specific detailed structures can be appropriately changed.

DESCRIPTION OF SYMBOLS 10 Solidification improved body 20 Core material 21 1st reinforcement 22 2nd reinforcement 23 Reinforcement member 24 Steel bar 30 Reinforcement reinforcement assembly 100 Ground improvement pile G Ground H Drilling hole

Claims (5)

A ground improvement pile having a solidified improvement body provided in a drilling hole formed in a vertical direction on the ground, and a core material embedded in the solidification improvement body,
The core material is
A steel bar extending along the axis of the solidified body,
A plurality of first reinforcing bars wound around the steel bar so as to project in one direction intersecting with the extending direction of the steel bar, and welded at at least a part of the circumferential surface of the steel bar to be in line contact; ,
A plurality of second reinforcing bars that are wound around at least a part of the circumferential surface of the steel bar and are wound around the steel bar so as to extend in a direction crossing the extending direction of the steel bar and crossing the one direction. When,
With
The first reinforcing bar and the second reinforcing bar are respectively disposed at an arbitrary interval in the extending direction of the bar steel, and the ground improvement pile is characterized by the above.   2. The ground improvement pile according to claim 1, wherein the first reinforcing bar and the second reinforcing bar are provided at a narrower interval toward a lower end side of the steel bar.   The arrangement according to claim 1 or 2, wherein the first reinforcing bar and the second reinforcing bar are arranged so that they are in contact with each other, and the first reinforcing bar is positioned above the second reinforcing bar. Ground improvement pile.   A reinforcing member welded to the peripheral surface of the bar steel is provided at a location where the first reinforcing bar is welded to the peripheral surface of the bar steel and arranged in contact with the upper side of the first reinforcing bar. Item 3. Ground improvement pile according to item 3.   The core material is provided inside the excavation hole so that the solidified improvement body is interposed around the core material and between the bottom of the excavation hole and the lower end portion of the bar steel. The ground improvement pile according to any one of claims 1 to 4, wherein the pile is improved.

Images