Yamureme Wall Structure

Abstract

To provide an earth-retaining wall structure and a construction method of the earth-retaining wall structure allowing depth of a buttress improving body to be shortened and increase of an improving volume to be suppressed.SOLUTION: An earth-retaining wall structure 1 set around an excavation area B of a ground A is provided with: an earth-retaining wall 11 arranged on a boundary between the ground and the excavation areas; a buttress improving body 12 extending a direction generally orthogonal to the earth-retaining wall in the excavation area of the earth-retaining wall; and a batholith improving body 13 continuously installed on a lower end 12a of the buttress improving body.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention is a method for fabricating an earth retaining wall structure. To make Regarding. [Background technology]

[0002] In excavation work, earth retaining walls are generally installed to prevent ground collapse. Methods for suppressing displacement of earth retaining walls include increasing the rigidity of the wall and increasing the number of strut support stages. However, when the excavated ground is a thick, soft layer, the displacement of the earth retaining wall below the bottom of the excavation is large, and these measures alone are not sufficient to suppress displacement of the earth retaining wall. For this reason, in excavation work on soft ground, a method of improving the ground on the excavation side adjacent to the earth retaining wall into a buttress type (buttress type) has become widespread in order to suppress displacement of the earth retaining wall (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 7-127064 Summary of the Invention [Problem to be solved by the invention]

[0004] Buttress-type improved bodies often move and rotate almost like rigid bodies, so in order to achieve sufficient deformation prevention, it is necessary to drive the improved ground down to the hard ground to increase the bearing capacity of the bottom of the improved body and prevent rotation. However, when the thickness of the soft ground is large compared to the excavation depth, the ground improvement depth becomes very large, and because the bottom area of ​​a single row of buttress-type improved bodies is relatively small, in order to achieve sufficient deformation prevention, it is necessary to improve multiple rows, increasing the improved width and length considerably, which poses challenges such as an increase in the improved volume and the cost of the measure.

[0005] The present invention has been made in consideration of the above-mentioned problems, and provides a retaining wall structure that can shorten the depth of the buttress-type improved body and suppress the increase in the improved volume. Construction The purpose is to provide. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, the retaining wall structure of the present invention is characterized in that it is an earth retaining wall structure that is set up around an excavation area of ​​the ground, and comprises an earth retaining wall set up at the boundary between the ground and the excavation area, a buttress-type improvement body that extends on the excavation area side of the earth retaining wall in a direction approximately perpendicular to the earth retaining wall in a plan view, and a base improvement body that is connected to the lower end of the buttress-type improvement body.

[0007] According to this invention, by providing a base improvement body connected to the lower end of the buttress-type improved body, the same effect as increasing the bottom area of ​​the buttress-type improved body can be achieved. As a result, the reaction force at the bottom can be increased, which increases the effect of suppressing deformation of the retaining wall, making it possible to shorten the depth of the buttress-type improved body and suppress an increase in the improved volume.

[0008] In addition, in the retaining wall structure according to the present invention, the base improvement body may be formed in a circular shape or a shape consisting of a series of circles that encompasses the buttress-type improvement body in a plan view.

[0009] According to this invention, by improving the base improvement body to a position further away from the retaining wall than the buttress-type improvement body, the effect of preventing rotational deformation can be increased without increasing the area of ​​the base improvement body.

[0010] The construction method for an earth retaining wall structure according to the present invention is a construction method for an earth retaining wall structure installed around an excavation area in the ground, comprising the steps of: constructing an earth retaining wall installed at the boundary between the ground and the excavation area; constructing a buttress-type improvement body on the excavation area side of the earth retaining wall, the buttress-type improvement body extending in a direction approximately perpendicular to the earth retaining wall in a plan view; and constructing a base improvement body connected to the lower end of the buttress-type improvement body, wherein the base improvement body is constructed using a high-pressure jet mixing method.

[0011] According to this invention, the bottom area can be increased by providing a bottom improvement body constructed using the high-pressure jet mixing method at the tip depth of the buttress-type improvement body. As a result, the bottom reaction force can be increased, and a large bottom reaction force can be secured even in non-hard ground, making it possible to shorten the depth of the buttress-type improvement body and suppress the increase in the improvement volume. In addition, the bottom improvement body can be constructed efficiently using the high-pressure jet mixing method. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide an earth retaining wall structure that can shorten the depth of the buttress-type improved body and suppress the increase in the improved volume. Construction can be provided. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 2 is a side view of the retaining wall structure according to the present embodiment. [Figure 2] FIG. 2 is a plan view of the retaining wall structure according to the present embodiment. [Figure 3] FIG. 10 is a side view of a retaining wall structure according to a first modified example of the present embodiment. [Figure 4] FIG. 10 is a plan view of an earth retaining wall structure according to a first modified example of the present embodiment. [Figure 5] FIG. 10 is a side view of a retaining wall structure according to a second modified example of the present embodiment. [Figure 6] FIG. 10 is a plan view of an earth retaining wall structure according to a modified example 2 of the present embodiment. [Figure 7] FIG. 10 is a side view of another aspect of the retaining wall structure of this embodiment. [Figure 8] FIG. 10 is a plan view of another aspect of the retaining wall structure of this embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, an earth retaining wall structure and a construction method for an earth retaining wall structure according to an embodiment of the present invention will be described with reference to Figs.

[0015] As shown in Figures 1 and 2, the retaining wall structure 1 of this embodiment is provided in the ground A and comprises a retaining wall 11 provided at the boundary between the ground A and the excavation area B, a buttress-type improvement body 12 extending in a direction approximately perpendicular to the retaining wall 11 in a plan view on the excavation area B side of the retaining wall 11, and a base improvement body 13 connected to the lower end 12a of the buttress-type improvement body 12 and provided at a depth capable of stably supporting the buttress-type improvement body 12.

[0016] The earth retaining wall 11 was constructed using a conventionally known construction method, such as the soil cement column wall method, the steel pipe sheet pile method, the diaphragm wall method, the pier and horizontal sheet pile method, and the steel sheet pile method. The earth retaining wall 11 is provided around the entire boundary between the ground A and the excavation area B.

[0017] The buttress-type improvement body 12 is a plate-like member installed within excavation area B. The buttress-type improvement body 12 is formed, for example, by the soil cement column wall construction method. The buttress-type improvement body 12 may also be formed by a deep mixing method or a high-pressure jet mixing method that can also improve the ground into a plate shape. The buttress-type improvement body 12 is formed over a predetermined range in a direction approximately perpendicular to the retaining wall 11 in a plan view. The buttress-type improvement body 12 is constructed from near the surface of the ground A to a depth where, when excavation of excavation area B is completed, the buttress-type improvement with a base plate can be expected to be sufficiently effective in preventing displacement of the retaining wall.

[0018] The bottom improvement body 13 is provided connected to the lower end 12a of the buttress-type improvement body 12. The bottom improvement body 13 is formed in a substantially circular shape in plan view. As shown in Figures 7 and 8, the bottom improvement body 13 may be formed by connecting multiple bottom improvement bodies that are substantially circular in plan view. The top surface of the bottom improvement body 13 is arranged so that it faces vertically upward. The bottom improvement body 13 is also connected to the retaining wall 11. The bottom improvement body 13 is formed to a size that encompasses the buttress-type improvement body 12 in plan view. The bottom improvement body 13 is formed using a high-pressure jet mixing method.

[0019] The construction method of the buttress-type improved body 12 and the bedrock improved body 13 of this embodiment will be described below. Prior to the construction of the buttress-type improved body 12, the ground near the bottom depth of the planned buttress-type improved body 12 is improved (bedrock improvement) using a high-pressure jet mixing method with a diameter larger than the bottom width of the buttress-type improved body 12, and then the bedrock improved body 13 is constructed. After the bedrock improved body 13 is constructed, the buttress-type improved body 12 is constructed so that it is supported by the bedrock improved body 13.

[0020] The retaining wall structure 1 of this embodiment comprises a retaining wall 11 installed at the boundary between the ground A and the excavation area B, a buttress-type improvement body 12 extending in a direction approximately perpendicular to the retaining wall 11 in a plan view on the excavation area B side of the retaining wall 11, and a base improvement body 13 connected to the lower end 12a of the buttress-type improvement body 12.

[0021] In this way, by providing the base improvement body 13 at the lower end of the buttress-type improvement body 12, the bottom area can be increased. As a result, the bottom reaction force can be increased. By increasing the bottom area, a bottom reaction force similar to that of hard ground can be secured even in relatively soft ground, which makes it possible to shorten the depth of the buttress-type improvement body 12 and suppress an increase in the improvement volume.

[0022] In addition, the base improvement body 13 can increase the bottom support force of the buttress-type improvement body 12, preventing rotation, and the bottom friction of the base improvement body 13 is also expected to have an effect of preventing horizontal movement, so even in relatively soft ground or with a small number of rows of buttress-type improvement bodies 12, a significant effect can be achieved in preventing deformation of the retaining wall 11.

[0023] The size of the bottom improvement body 13 is calculated based on the ground conditions and the bottom bearing capacity required to prevent deformation. The thickness and strength of the bottom improvement body 13 are determined so as to ensure safety against the load acting on the bottom improvement body 13.

[0024] (Variation 1) 3 and 4 show a first modified example of the above embodiment. The first modified example differs from the above embodiment in the construction position of the bottom improvement body 13 in plan view.

[0025] The bottom improvement body 13A of variant 1 is provided connected to the lower end 12a of the buttress-type improvement body 12. The bottom improvement body 13A is formed in a substantially circular shape in plan view. The top surface of the bottom improvement body 13 is arranged so that it faces vertically upward. The bottom improvement body 13 is provided at a distance from the retaining wall 11. The bottom improvement body 13 is formed to a size that encompasses the end 12b of the buttress-type improvement body 12 opposite the retaining wall 11 in plan view. The bottom improvement body 13 is formed by a high-pressure jet mixing method. Note that the bottom improvement body 13A may also be formed by connecting multiple bottom improvement bodies that are substantially circular in plan view.

[0026] According to the configuration of variant example 1, the base improvement body 13A is located away from the retaining wall 11 and encompasses the end 12b of the buttress-type improvement body 12, thereby more efficiently exerting the rotation prevention effect of the buttress-type improvement body 12.

[0027] (Variation 2) 5 and 6 show Modification 2 of the above embodiment. Modification 2 differs from Modification 1 above in the configuration of the buttress-type improved body 12.

[0028] The buttress-type improved body 12A of Variation 2 is composed of multiple plate-shaped members installed within the excavation area B. The buttress-type improved body 12A is formed, for example, by the soil cement column wall construction method. The buttress-type improved body 12 is formed over a predetermined range in a direction approximately perpendicular to the retaining wall 11 in a plan view. As shown in Figure 6, the buttress-type improved body 12A is composed of three plate-shaped members. The middle buttress-type improved body 21 is formed with a longer improved length than the buttress-type improved bodies 22 and 23 on either side. In other words, the improved length from the retaining wall 11 to the end 12b of the middle buttress-type improved body 21 is longer than the improved length from the retaining wall 11 to the end 12b of the buttress-type improved bodies 22 and 23 on either side. The buttress-type improved bodies 22 and 23 on both sides are formed with approximately the same improved length. The buttress-type improved body 12 is constructed from near the surface of the ground A to a depth at which the buttress-type improved body 12A can be maintained in a stable state without collapsing when excavation of the excavation area B is completed.

[0029] The bottom improvement body 13A is provided adjacent to the lower end 12a of the buttress-type improvement body 12A. The bottom improvement body 13A is formed in a substantially circular shape in plan view. The top surface of the bottom improvement body 13 is arranged so that it faces vertically upward. The bottom improvement body 13 is provided at a distance from the retaining wall 11. The bottom improvement body 13 is formed to a size that encompasses all of the end portions 12b of the buttress-type improvement bodies 21, 22, and 23 on the side opposite the retaining wall 11 in plan view. The bottom improvement body 13 is formed using a high-pressure jet mixing method.

[0030] According to the configuration of variant example 2, the load applied to the base improvement body 13A is greatest at the end 12b of the buttress-type improvement body. Therefore, by changing the width (length) of the buttress-type improvement bodies 21, 22, and 23, the load applied from the buttress-type improvement body 12A to the base improvement body 13A can be distributed, making it more difficult for the base improvement body 13A to rotate, thereby further enhancing the effect.

[0031] The above describes embodiments of the earth retaining wall structure and construction method for the earth retaining wall structure according to the present invention, but the present invention is not limited to the above embodiments and can be modified as appropriate within the scope of the gist of the present invention.

[0032] For example, the arrangement of the bottom improvement bodies 13, 13A in the above embodiment is merely an example, and the size and position of the bottom improvement bodies that have the highest deformation suppression effect can be determined depending on the conditions.

[0033] Furthermore, in the above embodiment, the buttress-type improvement body 12 was described as being constructed using the same mechanically mixed soil cement column wall method as the retaining wall 11, but the base improvement body 13 and the buttress-type improvement body 12 may also be constructed (ground improvement) consecutively using, for example, a high-pressure injection mixing method that can be used to improve the ground into a wall shape.

[0034] Furthermore, in the above embodiment, the bottom improvement body 13 is described as being formed in a circular shape when viewed from above, but the shape when viewed from above may be other than a circular shape. [Explanation of symbols]

[0035] 1…Mountain retaining wall structure 11...Retaining wall 12, 12A...Improved buttress type 12a…lower end 13,13A…Bottom board improvement body 21, 22, 23...Improved buttress type A...Ground B: Excavation area

Claims

1. In a retaining wall structure installed around an excavation area of ​​the ground, A retaining wall provided at the boundary between the ground and the excavation area; a buttress-type improvement body extending in a direction substantially perpendicular to the retaining wall in a plan view on the excavation area side of the retaining wall; a bottom improvement body connected to the lower end of the buttress-type improvement body, A retaining wall structure in which the bottom area of ​​the base improvement body is larger than the bottom area of ​​the buttress-type improvement body.

2. 2. The earth retaining wall structure according to claim 1, wherein the bottom improvement body is formed in a circular shape or a shape consisting of a series of circles that encompasses at least a portion of the buttress-type improvement body in a plan view.

3. A retaining wall structure as described in Claim 1, wherein the base improvement body is arranged at a distance from the retaining wall.

4. The buttress-type improved body is configured with a plurality of plate-like members arranged in parallel in a plan view, 4. The retaining wall structure according to claim 1, wherein the buttress-type improvement body in the middle is formed with a longer improvement length than the buttress-type improvements on both sides.

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