Ground improvement body, construction method of ground improvement body, and foundation structure

Abstract

To provide a ground improvement body, a construction method of a ground improvement body, and a foundation structure that enable reinforcement with a simple configuration.SOLUTION: A ground improvement body 1 formed in a wall shape from a surface of the ground downward comprises a main body 10 formed in a wall shape from a mixture of soil and solidification material, and a planar reinforcement body 20 pushed into the main body 10 from the ground surface before hardening and embedded in a planar shape to be integrated with it. In the main body 10, the planar reinforcement body 20 extends downward from the ground surface. The planar reinforcement body 20 is formed of a plurality of layers spaced apart in a thickness direction of the main body 10.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a ground improvement body, a method for constructing a ground improvement body, and a foundation structure. [Background technology]

[0002] As public infrastructure such as tunnels and bridges age, it has become essential to reinforce their foundations. Reinforcing foundations involves driving a large number of sheet piles or steel pipe sheet piles into the ground to improve the strength of the ground. This improves the earthquake resistance of the foundations and makes it possible to avoid the need for extensive renovation work.

[0003] For example, Patent Document 1 discloses a reinforcement structure for an existing foundation. In this invention, a first formwork made of protruding steel plates is installed to surround the outside of the existing foundation, a second formwork made of steel pipe sheet piles is installed to surround the outside of the first formwork, and a filler material such as concrete is filled between the first and second formworks to integrate the existing foundation, the first formwork, and the second formwork to construct a new foundation for a bridge pier. With this configuration, it is possible to reinforce existing foundations such as bridge piers using steel pipe sheet piles without damaging them. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-095907 Summary of the Invention [Problem to be solved by the invention]

[0005] By the way, when reinforcing the piers of large bridges, it may be necessary to use steel pipe sheet piles, but when reinforcing relatively small existing bridges, this may result in over-design and may not be reasonable.

[0006] Therefore, an object of the present invention is to provide a ground improvement body, a method for constructing a ground improvement body, and a foundation structure that enable reinforcement with a simple configuration. [Means for solving the problem]

[0007] In response to the above-mentioned problems, the ground improvement body of the present invention is a ground improvement body formed in a wall shape downward from the surface of the ground, and is characterized in that it comprises a main body portion formed in a wall shape by mixing soil and solidification material, and a planar reinforcement body that is embedded in a planar shape in the main body portion and integrated with it, and in that the planar reinforcement body extends downward from the ground surface in the main body portion.

[0008] Here, it is preferable that the sheet reinforcing body is formed in a plurality of layers spaced apart in the thickness direction of the main body, and that the sheet reinforcing body has a plurality of through holes formed therein that penetrate the sheet reinforcing body in the thickness direction.

[0009] In addition, the method for constructing a ground improvement body of the present invention is a method for constructing a ground improvement body formed in a wall-like shape downward from the surface of the ground, and is characterized by comprising a ground improvement process for forming a wall-like main body portion formed by mixing soil and solidification material, and an embedding process for pushing a planar reinforcement body from the ground surface into the main body portion before it hardens.

[0010] Here, the embedding step is preferably performed by pushing a rod-shaped body, which is disposed at the lower end of the sheet reinforcement body and whose longitudinal direction is the width direction of the main body, in the depth direction. Also, the embedding step is preferably performed by connecting the upper end of the sheet reinforcement body to a foundation structure provided on the surface of the ground.

[0011] The present invention also provides a foundation structure constructed by the above-mentioned method for constructing a ground improvement body, in which an edge separation member is interposed between the upper end and the main body portion. [Effects of the Invention]

[0012] The ground improvement body of the present invention has a main body formed in the shape of a wall by mixing soil and solidification material, in which a planar reinforcement body is buried in a planar shape and integrated, and in the main body, the planar reinforcement body extends downward from the ground surface.

[0013] This increases the contact area between the main body and the sheet reinforcement by the amount of sheet reinforcement. Therefore, compared to using rod-shaped reinforcement, it is possible to improve tensile resistance and shear resistance with a simpler structure. Furthermore, while sheet reinforcement has traditionally been used primarily in the horizontal direction, this provides a new method of using it in the vertical direction.

[0014] In particular, when the sheet reinforcement is formed in multiple layers spaced apart in the thickness direction of the main body, a greater reinforcing effect can be obtained compared to when the sheet reinforcement is a single layer.

[0015] The sheet-like reinforcing member also has a plurality of through-holes formed therethrough in the thickness direction, allowing the surrounding solidification material to be continuous through the through-holes, thereby enhancing the unity with the main body.

[0016] In addition, in the method for constructing a ground improvement body, a wall-shaped main body is formed by mixing soil and solidification material, and a sheet reinforcement is then pressed into the main body from the ground surface before it hardens. This increases the contact area between the main body and the sheet reinforcement by the amount of planar formation, thereby improving the foundation reinforcement effect compared to rod-shaped reinforcement.

[0017] The embedding process is performed by pushing a rod-shaped body, the width of which is the longitudinal direction of the main body located at the bottom end of the sheet reinforcement, into the depth direction, which ensures that the sheet reinforcement can be reliably pushed to the desired depth and achieves the expected reinforcement effect.

[0018] Furthermore, in the connection process, the upper end of the sheet reinforcement body is connected to the foundation structure installed on the ground surface, which fixes the foundation structure to the ground improvement body via the sheet structure, thereby reliably preventing the foundation structure from tipping over.

[0019] In addition, in the foundation structure constructed by the method for constructing ground improvement bodies, a separation member is interposed between the upper end of the sheet reinforcement body and the main body, which allows the sheet reinforcement body itself to fully demonstrate its tensile performance. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 2 is a cross-sectional view of a ground improvement body according to an embodiment of the present invention. [Figure 2] 1(a) is a front view of the sheet-like reinforcement body, and FIG. 1(b) is a side view of the sheet-like reinforcement body. [Figure 3] FIG. 2 is an explanatory diagram showing each step of the method for constructing a ground improvement body according to the embodiment. [Figure 4] FIG. 2 is an explanatory diagram showing each step of the method for constructing a ground improvement body according to the embodiment. [Figure 5] FIG. 2 is an explanatory diagram showing each step of the method for constructing a ground improvement body according to the embodiment. [Figure 6] FIG. 2 is an explanatory diagram showing each step of the method for constructing a ground improvement body according to the embodiment. [Figure 7] FIG. 2 is an explanatory diagram showing each step of the method for constructing a ground improvement body according to the embodiment. [Figure 8] FIG. 2 is an explanatory diagram showing each step of the method for constructing a ground improvement body according to the embodiment. [Figure 9] An explanatory diagram showing the process of connecting the ground improvement body to the foundation structure according to the embodiment. [Figure 10] An explanatory diagram showing the process of connecting the ground improvement body to the foundation structure according to the embodiment. [Figure 11] FIG. 2 is a diagram illustrating a base structure according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a cross-sectional view of a ground improvement body 1 according to an embodiment of the present invention. Fig. 2(a) is a front view of a planar reinforcement body 20, and Fig. 2(b) is a side view of the planar reinforcement body 20.

[0022] As shown in FIG. 1, the ground improvement body 1 is a wall-shaped structure formed below the ground surface G. The ground improvement body 1 is configured to have a main body 10 and a planar reinforcing body 20.

[0023] The main body 10 is formed into a wall shape extending in the depth direction of the page by mixing soil and a solidification material. The soil of the main body 10 corresponds to excavated soil from the original ground or excavated soil from another location. The solidification material can be cement-based solidification materials such as cement milk or mortar. Specifically, the main body 10 corresponds to improved soil constructed by injecting cement milk into excavated ground and stirring it, liquefied soil filled into trenches excavated in the ground, or a solidified wall constructed by adding a solidification material to muddy water filled into an excavated trench. The depth and width of the main body 10 are not particularly limited.

[0024] The sheet reinforcement 20 is embedded in a planar manner in the main body 10 and is integrated therewith. In the main body 10, the sheet reinforcement 20 extends in the depth direction D. The single sheet reinforcement 20 is folded below the main body 10 to form a two-layer structure in the thickness direction of the main body 10. In the following description, the portion of the sheet reinforcement 20 that is embedded in the main body 10 is referred to as the buried portion 21, and the portion that is exposed above ground from the ground surface G is referred to as the exposed portion 22. The buried portions 21 are arranged at an interval W in the thickness direction of the main body 10.

[0025] 2(a) and 2(b), a plurality of through holes 20a are formed in the sheet reinforcing member 20, penetrating the sheet reinforcing member 20 in the thickness direction. The plurality of through holes 20a are regularly arranged in a grid pattern in the vertical and horizontal directions, but are not limited to such an arrangement and hole shape.

[0026] The sheet reinforcement 20 is a so-called geotextile, which is a flexible sheet-like member. The sheet reinforcement 20 is embedded in the main body 10 to reinforce the ground improvement body 1. The sheet reinforcement 20 is, for example, made by weaving a polymer fiber material into a sheet shape, and has water permeability. Note that the sheet reinforcement 20 may be made of natural fibers, metal, etc., as long as it can form multiple through holes 20a.

[0027] Next, a method for constructing the soil improvement body 1 will be described with reference to Figures 3 to 8. For convenience of explanation, the main body 10 will be omitted from the illustrations as appropriate.

[0028] First, as shown in Fig. 3, a pair of guide members 50 are arranged along the width direction of the main body 10 so as to straddle the surface 10a of the main body 10. The guide members 50 are made of steel, such as H-beams. The guide members 50 may be arranged so that the spacing between them (the distance in the thickness direction of the main body 10) is approximately the same as the spacing W between the embedded portions 21, as shown in Fig. 1.

[0029] Next, as shown in Fig. 4, the sheet reinforcement 20 is placed so as to cover a portion of the pair of guide members 50. In addition, marks M are added at four locations along the longitudinal direction of the sheet reinforcement 20 to indicate the depth to which it will be buried. The marks M are provided to indicate the depth to which the sheet reinforcement 20 will be buried.

[0030] Next, as shown in Fig. 5, the planar reinforcement body 20 is pushed into the main body 10 using a penetration jig 60 and a rod-shaped body 70. In Figs. 5 to 8, the planar reinforcement body 20 is shown by a two-dot chain line, taking into consideration the illustration of other members.

[0031] The penetration jig 60 is configured to have a top end 61 extending horizontally and a pair of legs 62 extending downward from the top end 61. The top end 61 and the legs 62 are both configured from steel material such as H-beams.

[0032] The rod-shaped body 70 is, for example, a cylindrical metal member. The rod-shaped body 70 is arranged so that its longitudinal direction coincides with the width direction of the main body 10. By placing the rod-shaped body 70 on the sheet reinforcement body 20, a load is applied to the sheet reinforcement body 20 in the vertical downward direction, and the rod-shaped body 70 can cooperate with the penetration jig 60 to press the sheet reinforcement body 20 into the main body 10.

[0033] With the legs 62 positioned between the pair of guide members 50, the top end 61 is pressed downward, causing the legs 62 to push the rod-shaped body 70 downward in the depth direction D (vertically downward). As the rod-shaped body 70 is pushed downward, the planar reinforcing body 20 is also pushed downward, forming a protrusion P that is convex downward.

[0034] 6, the planar reinforcement body 20 is bent into a U-shape in a side view, and the restricting member 80 is joined at the position of the mark M with a binder 81. Opposing planar portions of the planar reinforcement body 20 are joined together with the restricting member 80.

[0035] The restricting member 80 is formed to be longer than the width of the pair of guide members 50, and extends in a direction intersecting the extension direction of the guide members 50. The restricting member 80 is a member made of metal such as steel, but may be any member as long as it can withstand the pressing force of the penetration jig 60.

[0036] 6, the penetration jig 60, which is housed in the U-shaped bent sheet-like reinforcement body 20, penetrates the sheet-like reinforcement body 20 together with the rod-shaped body 70 in the depth direction D. The penetration of the sheet-like reinforcement body 20 in the depth direction D continues until the regulating member 80 comes into contact with the guide member 50.

[0037] 7, when the regulating member 80 is pushed down to the position of the guide member 50, the penetration jig 60 is pulled up. That is, once the sheet reinforcement 20 has been buried to the desired depth, the penetration jig 60 is removed. In this way, the regulating member 80 functions as a stopper that prevents the sheet reinforcement 20 from sinking below a certain depth in the main body 10.

[0038] The rod-shaped body 70 may be pulled up together with the penetration jig 60, or may remain buried together with the sheet reinforcement 20. If the rod-shaped body 70 remains buried, a load is maintained on the sheet reinforcement 20 in the depth direction D (vertical direction), preventing the sheet reinforcement 20 from rising as the penetration jig 60 rises. In particular, if the ground is made of a highly viscous material, the heavier the weight of the rod-shaped body 70 placed on the sheet reinforcement 20, the more effectively it can prevent the sheet reinforcement 20 from rising.

[0039] Finally, as shown in Figure 8, the sheet reinforcement 20 is folded so that it is convex downward and embedded in the main body 10. Specifically, the sheet reinforcement 20 is configured to have an embedded portion 21 embedded in the main body 10 and an exposed portion 22 exposed above ground. The ratio of the embedded portion 21 to the exposed portion 22 in the sheet reinforcement 20 is not particularly limited, but the higher the ratio of the embedded portion 21, the greater the reinforcing effect that can be obtained. The restricting member 80 may be left integrated with the sheet reinforcement 20, or may be removed.

[0040] As described above, conventionally, the sheet reinforcement 20, such as a geotextile, has been mainly used by being placed horizontally in the ground. In contrast, in this embodiment, as shown in Figures 1 and 8, the sheet reinforcement 20 is mainly placed along the depth direction of the ground improvement body 1. This specification itself is one of the features of the present invention that has not been seen in the past.

[0041] Next, a foundation structure constructed by the method for constructing a soil improvement body will be described with reference to Figures 9 to 11. Figures 9 to 11 are explanatory diagrams of the steps for constructing a foundation structure according to the embodiment.

[0042] As shown in Figure 9, a ground improvement body 1 is provided below the ground surface G. In addition, a foundation structure 200 is placed on the ground surface G. The planar reinforcement body 20 is configured to have an embedded portion 21 embedded in the main body 10 and an exposed portion 22 exposed above ground.

[0043] An edge separating member 100 is provided on the ground surface G side of the main body 10. That is, the planar reinforcement body 20 extends from the ground to the ground surface side via the edge separating member 100 provided underground. The edge separating member 100 may be made of any material that has elasticity and impact resistance, such as elastite or glass wool.

[0044] As shown in Fig. 10, anchor bars 200a are arranged on the sides of the foundation structure 200. Reinforcing bars 110 are inserted into a plurality of through-holes 20a, for example, as shown in Fig. 2(a), and the reinforcing bars 110 and the anchor bars 200a are joined with binding wires (not shown). As a result, the exposed portions 22 are joined to the foundation structure 200 by the reinforcing bars 110.

[0045] 11, concrete members 120 are filled around the reinforcing bars 110 on the sides of the foundation structure 200, thereby integrating the exposed portions 22 with the foundation structure 200. This forms a foundation structure A in which the soil improvement body 1 and the foundation structure 200 are structurally separated by the separation member 100.

[0046] Interposing the edge separating member 100 between the ground improvement body 1 and the foundation structure 200 prevents the ground improvement body 1 and the foundation structure 200 from becoming integrated. Therefore, for example, when an earthquake occurs and the edge of the foundation structure 200 tries to lift up, the planar reinforcement body 20 connecting the ground improvement body 1 and the foundation structure 200 functions, making it easier for the planar reinforcement body 20 to exert its original function of imparting tensile resistance and shear resistance to the foundation structure 200. Note that multiple ground improvement bodies 1 may be placed below the foundation structure 200 in positions that do not overlap with the foundation structure 200 when viewed from above.

[0047] In this way, the ground improvement body 1 of this embodiment has a main body 10 formed in the shape of a wall by mixing soil and solidification material, and the planar reinforcement body 20 is embedded in a planar shape and integrated into the main body 10, and the planar reinforcement body 20 extends downward from the ground surface in the main body 10.

[0048] Therefore, the contact area between the main body 10 and the planar reinforcement 20 increases by the amount of planar formation. Therefore, compared to using rod-shaped reinforcement materials, it is possible to improve tensile resistance and shear resistance with a simple configuration. This makes it possible to perform reinforcement with a simple configuration. Furthermore, while conventionally, the planar reinforcement 20 has been used mainly along the lateral direction (horizontal direction), a new method of using it along the vertical direction (depth direction) can be provided.

[0049] In particular, when the sheet reinforcement 20 is formed in multiple layers spaced apart in the thickness direction of the main body 10, a greater reinforcing effect can be obtained compared to when the sheet reinforcement 20 is a single layer.

[0050] Furthermore, a plurality of through holes 20a are formed in the sheet-like reinforcing body 20 in the thickness direction, so that the surrounding solidified material is continuous through the through holes 20a, thereby enhancing the unity with the main body 10.

[0051] In addition, in the method for constructing the ground improvement body 1, a wall-shaped main body 10 is formed by mixing soil and sand with a solidification material, and the planar reinforcement body 20 is pressed from the ground surface into the main body 10 before it hardens. This increases the contact area between the main body 10 and the planar reinforcement body 20 by the amount of planar formation. Therefore, the foundation reinforcing effect can be improved compared to rod-shaped reinforcement materials.

[0052] The embedding step is performed by pushing the rod-shaped body 70, which is located at the lower end of the sheet reinforcement body 20 and whose longitudinal direction is the width direction of the main body 10, in the depth direction. This makes it possible to reliably push the sheet reinforcement body 20 to the desired depth, thereby achieving the expected reinforcing effect.

[0053] Furthermore, in the connection step, the upper end of the planar reinforcement body 20 is connected to the foundation structure 200 provided on the ground surface. This allows the foundation structure 200 to be fixed to the ground improvement body via the planar structure, making it possible to reliably prevent the foundation structure 200 from tipping over.

[0054] Furthermore, in the foundation structure A constructed by the construction method of the ground improvement body 1, an edge separation member 100 is interposed between the upper end of the sheet reinforcement body 20 and the main body 10. This allows the sheet reinforcement body 20 itself to fully demonstrate its tensile performance.

[0055] Although an embodiment of the present invention has been described above in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and design changes that do not deviate from the gist of the present invention are included in the present invention.

[0056] For example, in the above embodiment, an example was shown in which a single sheet-like reinforcement body 20 was folded to form multiple layers in the thickness direction of the main body portion 10, but multiple sheet-like reinforcement bodies 20 may also be embedded in the main body portion 10 without being folded to form multiple layers in the thickness direction of the main body portion 10.

[0057] In the above embodiment, the main body 10 of the ground improvement body 1 is made of improved soil, liquefied soil, or a solidified wall, but the present invention is not limited to this. For example, the main body 10 may be made of concrete or mortar. [Explanation of symbols]

[0058] 1: Ground improvement body 10: Main body 20: Planar reinforcement body 20a: Through hole 70: Rod-shaped body 100: Edge cutting material 200: Basic structure A: Basic structure D: Depth direction

Claims

1. A ground improvement body formed in a wall shape downward from the surface of the ground, a main body formed in a wall shape by mixing soil and a solidification material; a planar reinforcing body embedded in the main body portion in a planar manner and integrated therewith, A ground improvement body characterized in that in the main body portion, the planar reinforcement body extends downward from the ground surface.

2. 2. The ground improvement body according to claim 1, wherein the planar reinforcement body is formed in a plurality of layers spaced apart in the thickness direction of the main body portion.

3. 3. The ground improvement body according to claim 1, wherein the planar reinforcement body has a plurality of through holes formed therethrough in the thickness direction.

4. A method for constructing a ground improvement body formed in a wall shape downward from the surface of the ground, a ground improvement process in which a wall-shaped main body is formed by mixing soil and a solidification material; A method for constructing a ground improvement body, characterized by including an embedding step of pushing a planar reinforcement body into the main body part from the ground surface before hardening.

5. A method for constructing a ground improvement body as described in claim 4, characterized in that the embedding process is carried out by pushing a rod-shaped body, whose width direction of the main body portion arranged on the lower end side of the planar reinforcement body is the longitudinal direction, into the depth direction.

6. A method for constructing a ground improvement body as described in claim 4 or 5, characterized in that it includes a connection step for connecting the upper end of the planar reinforcement body to a foundation structure provided on the surface of the ground.

7. A foundation structure constructed by the method for constructing a ground improvement body according to claim 6, A foundation structure characterized in that an edge separating member is interposed between the upper end and the main body portion.

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