JP2010090638A - Soil improving method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for enhancing the strength of the soft ground compared with a conventional mattress method. <P>SOLUTION: This soil improving method for installing a mattress-like structure with an inside filling material filed in a frame body of approximately rectangular parallelepiped shape composed of geotextile, includes a frame body installation step of installing the frame body composed of geotextile with its bottom face and side faces integrated and with its upper face opened, on the ground or in the surface layer section of the ground; a first filling step of filling the inside filling material up to a predetermined height in the frame body; an interlay geotextile laying step of laying interlay geotextile almost horizontally on the inside filling material; a second filling step of further filling the inside filling material up to a predetermined height on the interlay geotextile; and an upper face forming step of forming the upper face of the frame body of geotextile integrated with the side faces of the frame body after the second filling step. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a ground improvement method capable of reinforcing a soft ground.

  When constructing and installing houses, retaining walls, buried pipes, etc. on soft ground, artificially created ground consisting of geotextile wrapped with crushed stone on the ground or the surface layer of the ground (Hereinafter, sometimes referred to as a “mattress-like structure.”) A method of reinforcing the ground (hereinafter also referred to as a “mattress method”) has been used.

As a technique related to the mattress construction method described above, for example, in Patent Document 1, a geotextile is laid in a mold standing on a soft ground, and the peripheral portion of the geotextile is erected upward into a surface layer material accommodating portion. Disclosed is a construction method in which an improved surface layer is constructed by filling a cement-based slurry, folding the peripheral edge onto the surface of the cement-based slurry, covering and fixing the opposing peripheral edges together, and curing the cement-based slurry. Has been.
Japanese Patent Laid-Open No. 11-140859

  Including the construction method disclosed in Patent Document 1, the effect of reinforcing the soft ground has been obtained even with the conventional mattress construction method. However, development of a construction method that can further increase the strength of the ground has been desired.

  Then, this invention makes it a subject to provide the construction method which can raise the intensity | strength of a soft ground rather than the conventional mattress construction method.

  The present invention will be described below. In addition, in order to make an understanding of this invention easy, the reference sign of an accompanying drawing is attached in brackets, However, This invention is not limited to the form of drawing.

  The present invention provides a mattress-like structure (1) in which a filling material (20) is filled in a substantially rectangular parallelepiped frame (10b) made of geotextile, on the ground, or on the surface of the ground (100). This is a ground improvement method to be installed on the ground, which is composed of geotextiles on the ground or on the surface layer of the ground, and the bottom surface (11) and the side surface (12) are integrated and the top surface is open. After the frame body installation step (S1), and after the frame body installation step, the filling material (20a) is filled to a predetermined height in the frame body, the first filling step (S2), and the first filling step After that, the insole geotextile (21) is laid on the filling material substantially horizontally. After the insole geotextile laying step (S3) and the insole geotextile laying step, on the insole geotextile. Fill the filling material (20b) to the specified height. And a second filling step (S4) and a top surface forming step (S5) for forming the upper surface (13) of the frame body with a geotextile integrated with the side surface of the frame body after the second filling step. The ground improvement method. In the present invention, the “filling material” is not particularly limited, and specifically, crushed stone or the like can be used.

  In the ground improvement method of the present invention, the insole geotextile is preferably a geotextile having a particularly strong tensile strength in the triaxial direction. By adopting such a configuration, the mattress-like structure can disperse a load applied from above in a wider range, and can withstand a higher load. Therefore, the construction method which can raise the intensity | strength of soft ground more can be provided.

  ADVANTAGE OF THE INVENTION According to this invention, the ground improvement construction method which can raise the intensity | strength of a soft ground rather than the conventional mattress construction method can be provided.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a flowchart schematically showing the steps of the ground improvement method according to the present invention. 2-7 is the top view and sectional drawing which show schematically a part of process in the ground improvement construction method of this invention. 2 to 7, the left side is a top view and the right side is a vertical sectional view taken along a broken line drawn on the left side. In FIGS. 2 to 7, some symbols are omitted to prevent the drawings from becoming complicated.

  As shown in FIG. 1, the ground improvement construction method of the present invention includes a frame body installation step (S1), a first filling step (S2), a geotextile installation step for insole (S3), and a second filling step (S4). And an upper surface forming step (S5). Each of these steps will be described in detail below.

1. Frame installation process (S1)
Step S1 is a step of installing a frame body that is made of geotextile on the ground or on the surface layer of the ground, the bottom surface and the side surfaces are integrated, and the top surface is open. Specifically, first, as shown in FIG. 2, a depression 101 having a size capable of embedding a mattress-like structure 1 (see FIG. 7) in the ground 100 is formed. And the wooden frame 102 along the side surface of the depression 101 is installed in the depression 101.

  After the installation of the wooden frame 102, as shown in FIG. 3, the frame 10a is distinguished from the frame 10a having an open upper surface (a frame 10b having a closed upper surface (see FIG. 7)). ). The frame body 10a is composed of a geotextile, and includes a bottom surface 11, side surfaces 12a, 12b, 12c, and 12d (only the two surfaces (side surfaces 12a and 12c) are shown in the right view of FIG. 3) and the frame body 10b. It consists of upper surface pieces 13a, 13b, 13c, and 13d that are part of the upper surface 13 (see FIG. 7).

  The bottom surface 11 has a substantially rectangular shape, and side surfaces 12a, 12b, 12c, and 12d (hereinafter, collectively referred to as “side surface 12”) are integrated on four sides thereof. The method of integrating these is not particularly limited, and may be configured by one geotextile, or may be configured by connecting a plurality of geotextiles using a conventionally known method. Adjacent side surfaces (12a and 12b, 12b and 12c, 12c and 12d, 12d and 12a) are also integrated, and these can be connected using a conventionally known method. Further, the upper surface piece 13a is opposite to the bottom surface 11 of the side surface 12a, the upper surface piece 13b is opposite to the bottom surface 11 of the side surface 12b, and the upper surface piece 13c is opposite to the bottom surface 11 of the side surface 12c. On the opposite side of the bottom surface 11, upper surface pieces 13d are integrated. The method for integrating them is not particularly limited, and may be constituted by one geotextile, or may be constituted by connecting a plurality of geotextiles using a conventionally known method.

First filling step (S2)
Step S2 is a step of filling the filling material 20a to a predetermined height in the frame 10a after the step S1, as shown in FIG. The predetermined height means a height (for example, about half of the height of the frame body 10b) where the insole geotextile 21 (see FIG. 5) is planned to be laid. Fill with compaction.

Geotextile laying process for insoles (S3)
Step S3 is a step of laying the insole geotextile 21 substantially horizontally on the filling material 20a after step S2, as shown in FIG.

Second filling step (S4)
Step S4 is a step of filling the filling material 20b to a predetermined height on the insole geotextile 21, as shown in FIG. That is, when the mattress-like structure 1 having only one layer of the geotextile 21 for the insole is to be produced, the filling material 20b is filled while being compacted to a height substantially equal to the height of the side surface 12.

Upper surface forming step (S5)
In step S5, after the surface height of the compacted filling material 20 becomes substantially the same as the height of the side surface 12, the upper surface of the frame 10a is closed and integrated with the side surface 12, as shown in FIG. This is a step of making the frame body 10b provided with the upper surface 13 made of the formed geotextile. As a specific example of the method of forming the upper surface 13, a method of forming the upper surface 13 by connecting the upper surface pieces 13a, 13b, 13c, and 13d, or another geotextile is prepared, and the upper surface pieces 13a, 13b are prepared. , 13c, and 13d to form the upper surface 13 by coupling. As a connection method in these cases, a known method can be used.

  In the description of the present invention so far, an example in which the insole geotextile is laid in one layer in the mattress-like structure has been described, but the present invention is not limited to such a form, and the mattress-like structure Multiple layers of geotextiles for insoles can be laid in the object. In that case, after the first second filling step, the insole geotextile laying step and the second filling step may be repeated up to a predetermined height.

  Examples of the geotextile that can be used in the present invention include a tensor manufactured by Mitsubishi Plastics, Inc. Conventionally, as a geotextile constituting a frame body of a mattress-like structure, a tencer having a mesh opening having a substantially square shape and a particularly strong tensile strength in two axial directions as shown in FIG. 8A is used. Such a tensor can also be used in the present invention. Further, as will be described later, as shown in FIG. 8B, the mesh opening has a substantially triangular shape, and has a particularly strong tensile strength in the triaxial direction. As a result, in all directions (360 degrees). It is preferable to use a reinforcing material having a truss structure having pseudo strength (for example, Geogrit disclosed in JP-A-2004-44374).

  A mattress-like structure with a geotextile frame that constrains the padding material exerts shear resistance when a load is applied from above, so that the ground is reinforced by installing and burying the mattress-like structure. be able to. Furthermore, in the mattress-like structure obtained by the ground improvement method of the present invention, since the insole geotextile is laid in the mattress-like structure as described above, it is more resistant to the load from above. It becomes possible.

  As the insole geotextile, it is preferable to use a geotextile having particularly strong strength in the triaxial direction. By adopting such a configuration, the load applied from the top of the mattress-like structure can be dispersed in a wider range, so that it can withstand a greater load from above. The principle will be described below with reference to FIG.

  FIG. 9 shows the tensile strength of a tensor having a particularly strong tensile strength in the biaxial direction like the tensor shown in FIG. 8A (hereinafter referred to as “Tensor a”), and FIG. 8B. It is a figure which shows the tensile strength of the tencer (henceforth "tenser b") which has especially strong tensile strength in such a triaxial direction. Concentric circles indicate the strength, and the numbers on the outer side of the outermost circle mean the direction (angle) having the strength. A solid line 91 is the tensile strength of the tensor a, and a broken line 93 is the tensile strength of the tensor b. A circle 92 drawn with a solid line inside the region surrounded by the solid line 91 is a circle that passes through the strength in the direction where the tensile strength of the tensor a is weakest. A circle 94 drawn by a broken line inside a region surrounded by a broken line 93 is a circle that passes through the strength in the direction where the tensile strength of the tensor b is the weakest.

  As shown in FIG. 9, the tensor a has a particularly strong strength in the biaxial directions (0 ° -180 ° and 90 ° -270 °), but the tensile strength in the other directions is relatively weak. The size is small. On the other hand, the tensor b has particularly strong strength in the triaxial directions (0 ° -180 °, 60 ° -240 °, and 120 ° -300 °), and the size of the circle 94 is large. That is, the tensor b has stronger strength in many directions than the tensor a. Therefore, with respect to the load applied from above, the tensor b can disperse the load in more directions than the tensor a.

  FIG. 10 shows a mattress-like structure of the present invention using a conventional mattress-like structure and a tensor b as an insole geotextile (hereinafter referred to as “mattress b”) when a load is applied from above. It is a figure which shows roughly stress distribution. FIG. 10A is a diagram of the stress distribution of the conventional mattress-like structure and the mattress b when viewed in a vertical section (two-dimensionally). FIG. 10B is a perspective view when the stress distribution of the mattress b is viewed three-dimensionally. FIG.10 (c) is a perspective view at the time of seeing the stress distribution of the conventional mattress-like structure three-dimensionally.

  As shown in FIG. 10A, in a conventional mattress-like structure and mattress b, when a load 200 is applied from above, the stress is distributed in a substantially trapezoidal shape when viewed in a vertical section. On the other hand, when viewed three-dimensionally, in the conventional mattress-like structure, stress is distributed in the biaxial direction as shown in FIG. 10C, whereas in the mattress b, the stress is distributed in FIG. As shown, the stress is distributed in all directions (360 degrees). This is because, as described above, the tensor b has a particularly strong tensile strength in the triaxial direction, and as a result, has a pseudo strength in all directions (360 degrees) and disperses the load in many directions. It is because it can do.

  While the present invention has been described in connection with embodiments that are presently the most practical and preferred, the present invention is not limited to the embodiments disclosed herein. However, it can be changed as appropriate without departing from the scope or spirit of the invention that can be read from the claims and the entire specification, and the ground improvement method involving such a change is also included in the technical scope of the present invention. Must be understood as.

It is a flowchart which shows roughly the process of the ground improvement construction method of this invention. It is the top view and sectional drawing which show a part of process in the ground improvement construction method of this invention roughly. It is the top view and sectional drawing which show a part of process in the ground improvement construction method of this invention roughly. It is the top view and sectional drawing which show a part of process in the ground improvement construction method of this invention roughly. It is the top view and sectional drawing which show a part of process in the ground improvement construction method of this invention roughly. It is the top view and sectional drawing which show a part of process in the ground improvement construction method of this invention roughly. It is the top view and sectional drawing which show a part of process in the ground improvement construction method of this invention roughly. It is a figure which shows roughly the example of the geotextile which can be used for this invention. It is a figure which shows roughly the comparison of the intensity | strength of the geotextile which can be used for this invention. It is a figure which shows roughly the stress distribution at the time of applying a load from the top.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Mattress-like structure 10a ... Frame body with opened top surface 10b ... Frame body 11 ... Bottom surface 12 ... Side surface 13 ... Upper surface 20 ... Filling material 21 ... Geotextile for insole 100 ... Ground 101 ... Recessed land 102 ... Wooden frame

Claims (2)

A ground improvement method for installing a mattress-like structure filled with filling material in a substantially rectangular parallelepiped frame made of geotextile on the ground or on the surface layer of the ground,
On the ground, or on the surface layer of the ground, the geotextile is configured with the frame body, and the bottom surface and the side surface are integrated and the frame body with the top surface opened is installed,
After the frame installation step, the inside filling material is filled with the filling material to a predetermined height, a first filling step,
After the first filling step, laying the insole geotextile on the filling material substantially horizontally, the insole geotextile laying step,
After the insole geotextile laying step, filling the insole geotextile on the insole geotextile to a predetermined height, a second filling step,
After the second filling step, an upper surface forming step of forming the upper surface of the frame body with a geotextile integrated with a side surface of the frame body;
A ground improvement construction method. The ground improvement construction method according to claim 1, wherein the insole geotextile is a geotextile having a particularly strong tensile strength in three axial directions.

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