JP2023166721A - Earth-retaining wall structure and construction method of earth-retaining wall structure - Google Patents

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

The present invention relates to a retaining wall structure and a method for constructing a retaining wall structure.

During excavation work, retaining walls are generally installed to prevent the ground from collapsing. Methods for suppressing the displacement of retaining walls include increasing the rigidity of retaining walls and increasing the number of struts of strut supports. However, when the ground to be excavated is a thick soft layer, the displacement of the retaining wall at depths below the bottom of the excavation is large, and these measures alone were not able to sufficiently suppress the displacement of the retaining wall. For this reason, in excavation work on soft ground, a method of improving the excavated side ground in contact with the retaining wall to a buttress type (buttress type) has become popular for the purpose of suppressing the displacement of the retaining wall. (For example, see Patent Document 1.)

Japanese Unexamined Patent Publication No. 7-127064

Buttress-type improved bodies often move and rotate almost like rigid bodies, so in order to obtain sufficient deformation prevention effects, the improved ground must be poured into hard ground to increase the supporting capacity of the bottom of the improved body. It is necessary to prevent rotation by However, if the thickness of the soft ground is large compared to the excavation depth, the depth of ground improvement will be very large, and the bottom area of a single row buttress type improvement structure is relatively small, so it is not possible to have a sufficient deformation suppressing effect. In order to achieve this, it is necessary to improve the width of the improvement by increasing the width of the improvement in multiple rows, or to increase the length of the improvement considerably, which poses problems such as an increase in the volume of improvement and an increase in the cost of countermeasures.

The present invention was made in view of the above-mentioned problems, and includes a retaining wall structure and a method for constructing a retaining wall structure that can shorten the depth of a buttress-type improved body and suppress an increase in the improved volume. The purpose is to provide

In order to achieve the above object, a mountain retaining wall structure according to the present invention includes a mountain retaining wall structure provided around an excavation area of the ground, which includes: a mountain retaining wall provided at a boundary between the ground and the excavation area; The excavation area side includes a buttress type improved body extending in a direction substantially perpendicular to the retaining wall in plan view, and a bottom plate improved body connected to the lower end of the buttress type improved body. .

According to this invention, the same effect as increasing the bottom area of the improved buttress type body can be obtained by providing the improved bottom plate body connected to the lower end of the improved buttress type body. As a result, the reaction force on the bottom surface can be increased, and the effect of suppressing deformation of the retaining wall is increased, so the depth of the buttress type improved body can be shortened and an increase in the improved volume can be suppressed.

Further, in the mountain retaining wall structure according to the present invention, the bottom plate improved body may be formed in a circular shape or a series of circular shapes that includes the buttress type improved body in a plan view.

According to this invention, by improving the bottom plate improvement body to a position further away from the retaining wall than the buttress type improved body, the effect of suppressing rotational deformation can be enhanced without increasing the area of the bottom plate improvement body.

A method for constructing a retaining wall structure according to the present invention includes a step of constructing a retaining wall provided at a boundary between the ground and the excavated region, and a step of constructing a retaining wall provided at a boundary between the ground and the excavated region; a step of constructing a buttress-type improved body extending in a direction substantially perpendicular to the retaining wall in plan view on the excavation area side; a step of constructing a bottom-base improved body connected to the lower end of the buttress-type improved body; The bottom plate improvement body is characterized in that it is constructed by a high-pressure injection stirring method.

According to this invention, the bottom area can be increased by providing the bottom plate improvement body constructed by the high-pressure injection stirring method at the depth of the tip of the buttress type improvement body. As a result, the bottom reaction force can be increased, and even if the ground is not hard, a large bottom reaction force can be secured, making it possible to shorten the depth of the buttress type improvement body and suppress the increase in the improvement volume. . In addition, the improved bottom plate can be efficiently constructed using the high-pressure injection stirring method.

According to the present invention, it is possible to provide a mountain retaining wall structure and a method for constructing a mountain retaining wall structure that can shorten the depth of a buttress type improved body and suppress an increase in the improved volume.

FIG. 2 is a side view of the retaining wall structure according to the present embodiment. FIG. 2 is a plan view of the retaining wall structure according to the present embodiment. It is a side view of the mountain retaining wall structure of the modification 1 of this embodiment. It is a top view of the mountain retaining wall structure of the modification 1 of this embodiment. It is a side view of the mountain retaining wall structure of the modification 2 of this embodiment. It is a top view of the mountain retaining wall structure of the modification 2 of this embodiment. It is a side view of the mountain retaining wall structure of another aspect of this embodiment. It is a top view of the mountain retaining wall structure of another aspect of this embodiment.

Hereinafter, a retaining wall structure and a method for constructing the retaining wall structure according to an embodiment of the present invention will be described based on FIGS. 1 to 6.

As shown in FIGS. 1 and 2, the retaining wall structure 1 of the present embodiment includes a retaining wall 11 provided in the ground A and provided at the boundary between the ground A and the excavation area B, and an excavation area of the retaining wall 11. An improved buttress type body 12 extending in a direction substantially perpendicular to the retaining wall 11 in plan view on the B side, and a depth that is connected to the lower end 12a of the improved buttress type body 12 and that can stably hold the improved buttress type body 12. An improved bottom plate 13 is provided.

The retaining wall 11 is constructed using a conventionally known construction method. Construction methods include the soil-cement column wall method, steel pipe sheet pile method, underground continuous wall method, parent pile horizontal sheet pile method, and steel sheet pile method. Note that the retaining wall 11 is provided around the entire boundary between the ground A and the excavation area B.

The buttress type improved body 12 is a plate-shaped member provided within the excavation area B. The buttress-type improved body 12 is formed by, for example, a soil-cement column wall construction method. The buttress-type improved body 12 may be formed by a deep mixing method, a high-pressure injection stirring method that can also be improved into a plate shape, or the like. The buttress type improved body 12 is formed in a predetermined range in a direction substantially perpendicular to the retaining wall 11 in plan view. The buttress type improvement body 12 is constructed from near the surface of the ground A to a depth at which the buttress type improvement with a bottom plate can be expected to have a sufficient effect in suppressing displacement of the retaining wall when excavation of the excavation area B is completed.

The bottom plate improved body 13 is provided continuously to the lower end 12a of the buttress type improved body 12. The bottom plate improved body 13 is formed in a substantially circular shape when viewed from above. In addition, as shown in FIGS. 7 and 8, the bottom plate improved body 13 may have a shape in which a plurality of substantially circular shapes in plan view are connected. The upper surface of the bottom plate improved body 13 is arranged so as to face vertically upward. The bottom plate improved body 13 is also connected to the retaining wall 11. The bottom plate improved body 13 is formed in a size that includes the buttress type improved body 12 in a plan view. The bottom plate improvement body 13 is formed by a high-pressure injection stirring method.

A construction method for the improved buttress type body 12 and the improved bottom plate body 13 of this embodiment will be explained. Before 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 with a diameter larger than the bottom width of the buttress type improved body 12 using a high-pressure injection stirring method (bottom base improvement). ) and construct the bottom plate improvement body 13. After the bottom plate improved body 13 is constructed, the buttress type improved body 12 is constructed so as to be supported by the bottom plate improved body 13.

The mountain retaining wall structure 1 of this embodiment includes a mountain retaining wall 11 provided at the boundary between the ground A and an excavation area B, and a mountain retaining wall 11 extending toward the excavation area B side of the mountain retaining wall 11 in a direction substantially perpendicular to the mountain retaining wall 11 in a plan view. It includes a buttress type improved body 12 and a bottom plate improved body 13 connected to a lower end 12a of the buttress type improved body 12.

By providing the bottom plate improved body 13 at the lower end of the buttress type improved body 12 in this way, the bottom area can be increased. As a result, the reaction force on the bottom surface can be increased. By increasing the bottom area, it is possible to secure a bottom reaction force similar to that of hard ground even on relatively soft ground, thereby shortening the depth of the buttress type improved body 12 and suppressing an increase in the improved volume. be able to.

In addition, the bottom plate improved body 13 can increase the bottom supporting force of the buttress type improved body 12 to suppress rotation, and the bottom friction of the bottom plate improved body 13 can also be expected to have an effect of suppressing movement in the horizontal direction. Even on soft ground or with a small number of rows of buttress type improved bodies 12, a great effect can be obtained in suppressing deformation of the retaining wall 11.

Note that the size of the base improvement body 13 is calculated based on the ground conditions and the base supporting force required to suppress deformation. The thickness and strength of the improved bottom plate 13 are determined so as to ensure safety against the load acting on the improved bottom plate 13.

(Modification 1)
3 and 4 show a first modification of the above embodiment. Modification 1 differs from the above embodiment in the construction position of the bottom plate improved body 13 in plan view.

The bottom plate improved body 13A of Modification 1 is provided continuously to the lower end 12a of the buttress type improved body 12. The bottom plate improved body 13A is formed in a substantially circular shape when viewed from above. The upper surface of the bottom plate improved body 13 is arranged so as to face vertically upward. The bottom plate improvement body 13 is provided apart from the retaining wall 11. The bottom plate improved body 13 is formed in a size that includes the end portion 12b of the buttress type improved body 12 on the opposite side to the retaining wall 11 in plan view. The bottom plate improvement body 13 is formed by a high-pressure injection stirring method. In addition, the bottom plate improved body 13A may have a shape in which a plurality of substantially circular pieces are connected in a plan view.

According to the configuration of Modified Example 1, the bottom plate improved body 13A is provided apart from the retaining wall 11 and includes the end portion 12b of the buttress type improved body 12, so that the rotation suppression effect of the buttress type improved body 12 is further enhanced. It can be used efficiently.

(Modification 2)
5 and 6 show a second modification of the above embodiment. Modification 2 is different from Modification 1 described above in the configuration of the improved buttress type body 12.

The buttress type improved body 12A of Modification 2 is composed of a plurality of plate-like members provided in the excavation area B. The buttress type improved body 12A is formed by, for example, a soil cement column wall construction method. The buttress type improved body 12 is formed in a predetermined range in a direction substantially perpendicular to the retaining wall 11 in plan view. As shown in FIG. 6, the improved buttress type body 12A is composed of three plate-shaped members. The middle buttress type improvement body 21 is formed with a larger improvement length than the buttress type improvement bodies 22, 23 on both sides. In other words, the improved length from the retaining wall 11 to the end 12b of the middle buttress-type improved body 21 is larger than the improved length to the ends 12b of the buttress-type improved bodies 22 and 23 on both sides. The buttress type improved bodies 22, 23 on both sides are formed with substantially the same improved length. The improved buttress type body 12 is constructed from near the surface of the ground A to a depth greater than the depth at which the improved buttress type body 12A can be stably maintained without falling down when excavation of the excavation area B is completed.

The bottom plate improved body 13A is provided in series with the lower end 12a of the buttress type improved body 12A. The bottom plate improved body 13A is formed in a substantially circular shape when viewed from above. The upper surface of the bottom plate improved body 13 is arranged so as to face vertically upward. The bottom plate improvement body 13 is provided apart from the retaining wall 11. The bottom plate improved body 13 is formed in a size that includes all of the end portions 12b of the buttress type improved bodies 21, 22, 23 on the side opposite to the retaining wall 11 in plan view. The bottom plate improvement body 13 is formed by a high-pressure injection stirring method.

According to the configuration of Modification Example 2, the load applied to the bottom plate improved body 13A is greatest at the end portion 12b of the buttress type improved body, so the width (length) of the buttress type improved body 21, 22, 23 is By changing, the load applied from the buttress type improved body 12A to the bottom plate improved body 13A can be dispersed, and the bottom plate improved body 13A becomes difficult to rotate, so that the effect can be further enhanced.

Although the embodiments of the mountain retaining wall structure and the construction method of the mountain retaining wall structure according to the present invention have been described above, the present invention is not limited to the above embodiments, and can be modified as appropriate without departing from the spirit thereof. be.

For example, the arrangement of the bottom plate improvement bodies 13, 13A in the above embodiment is merely an example, and the size and position of the bottom plate improvement bodies that have a high deformation suppressing effect may be determined depending on the conditions.

In addition, in the above embodiment, the buttress type improved body 12 was constructed using the same mechanically agitated soil cement column wall construction method as the retaining wall 11, but for example, a high-pressure injection agitation construction method that can be improved into a wall shape is used. Using this method, the bottom base improvement body 13 and the buttress type improvement body 12 may be constructed (soil improvement) in succession.

Further, in the above embodiment, the case where the bottom plate improved body 13 is formed in a circular shape in a plan view has been described, but the shape in a plan view may be other than a circular shape.

1... Mountain retaining wall structure 11... Mountain retaining wall 12, 12A... Buttress type improved body 12a... Lower end 13, 13A... Bottom plate improved body 21, 22, 23... Buttress type improved body A... Ground B... Excavation area

Claims (3)

In the retaining wall structure installed around the excavated area of the ground,
a retaining wall provided at the boundary between the ground and the excavation area;
a buttress-type improved body extending in a direction substantially perpendicular to the mountain retaining wall in plan view on the excavation area side of the mountain retaining wall;
A retaining wall structure comprising: an improved bottom plate body connected to a lower end of the buttress type improved body. The retaining wall structure according to claim 1, wherein the improved bottom plate is formed in a circular shape or a series of circular shapes that includes the buttress type improved body in a plan view. In the method of constructing a retaining wall structure around an excavated area of the ground,
a step of constructing a retaining wall provided at the boundary between the ground and the excavation area;
constructing a buttress-type improved body extending in a direction substantially perpendicular to the mountain retaining wall in plan view on the excavation area side of the mountain retaining wall;
A method for constructing a retaining wall structure, comprising: constructing a bottom plate improvement body connected to a lower end of the buttress type improved body, the bottom plate improvement body being constructed by a high-pressure injection stirring method.

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