JP2020147921A - Slope collapse preventing reinforcement body, reinforcer insertion method and slope collapse preventing reinforcement method - Google Patents

Abstract

To provide a collapse preventing reinforcement body enabling a flexible reinforcer to be installed on a center line of a borehole and a slope collapse preventing method using the same.SOLUTION: A slope collapse preventing reinforcement body 10 is installed in a borehole 8, which penetrates a moving clod in a natural ground of a slope and is drilled to an immovable natural ground. The slope collapse preventing reinforcement body comprises: a pressure bearing member 5 disposed on a surface layer part of the natural ground; and a reinforcer 6 that connects the pressure bearing member 5 and the immovable natural ground and is a flexible wire. The slope collapse preventing reinforcement body has two or more spacers 7 that are fixed to the reinforcer 6 and two or more guide wires 9 that are disposed in the borehole 8 in advance before the reinforcer 6 is inserted in the borehole 8. Penetration parts as many pieces as the guide wires 9 to make the guide wires 9 penetrate or fitting parts to be fitted to the guide wires 9 are formed in the spacer 7.SELECTED DRAWING: Figure 2

Description

The present invention relates to a collapse prevention reinforcing body that prevents the collapse of a sloping land. In particular, the drilling length is approximately 2 to 10 m, which is an intermediate region between the construction area of the ground reinforcement earthwork with a drilling length of about 2 to 5 m and the construction area of the ground anchor construction with a drilled length of approximately 7 to 10 m or more. The present invention relates to a collapse prevention reinforcing body and a collapse prevention method for sloping terrain using the collapse prevention reinforcing body for a region (more preferably, the drilling length is approximately 2 to 5 m, which will be described later).

Construction methods (Patent Documents 1, 2, etc.) for providing a collapse prevention reinforcing body to prevent the collapse of a sloping ground are roughly classified into ground anchor construction and ground reinforcement earthwork (also referred to as reinforcing bar insertion construction and rock bolt construction).

Ground anchoring is carried out by drilling holes in the ground on slopes to immovable ground (also called fixed area) through moving soil mass. The collapse prevention reinforcing body has a reinforcing material for connecting the bearing material provided on the surface layer portion of the ground and the immovable ground. The reinforcing material partially has a stretchable region (also referred to as a free length portion) that is not integrated with the immovable ground. The stretchable area has a double structure with a protective material.

The ground anchor work is a system for transmitting the acting tensile force to the ground. It is composed of an anchor body, a tension part, and an anchor head created by injecting grout. The difference from the ground reinforcement earthwork is that there is a stretchable area where the adhesive force between the ground and the reinforcing material (tensile material) does not work, which introduces prestress and actively prevents deformation of the ground. It is a point that can be done.

Ground reinforcement earthwork is also carried out by drilling holes in the ground on slopes to immovable ground through moving soil mass, and the collapse prevention reinforcement is a bearing material provided on the surface layer of the ground. It has a reinforcing material that connects to the immovable ground. The reinforcing material has a structure that is integrated with the immovable ground via a grout.

Ground reinforcement earthwork is a construction method in which a reinforcing material is inserted and placed in the ground to improve the behavior characteristics and strength of unstable soil mass by the interaction between the ground and the reinforcing material, and to improve the stability of slopes and slopes. Is. In other words, it is a construction method in which reinforcing bars are inserted and placed in the ground and integrated with the ground by grout, and the entire circumference (all holes) of the reinforcing material is filled with grout and fixed.

The ground reinforcement work can be distinguished from the ground anchor work because there is no expansion / contraction area where the PC steel wire or PC steel rod expands and contracts freely. Since there is no concept of introducing prestress in the ground reinforcement earthwork, the construction is completed simply by tightening the head with a nut.

Japanese Unexamined Patent Publication No. 2004-084407 Japanese Unexamined Patent Publication No. 8-135397

The existing slope stabilization works are targeted for drilling lengths of about 2 to 5 m for ground reinforcement earthwork and about 7 to several tens of m for ground anchor works. In these construction methods, deformed reinforcing bars and PC steel rods that are not flexible and have linearity are used when the drilling length is relatively short, but flexible PC steel is used when the drilling length is long. Stranded wire or unbonded PC steel stranded wire is used.

In the case of ground anchor work, there is no problem as long as the centering of the reinforcing material can be held in the fixing area via a spacer or the like. However, a method of filling grout over the entire length of the drilled hole, such as ground reinforcement earthwork, or an improved method of filling the grout only in the fixing region with an elastic region so that prestress can be introduced into the reinforcing material. When a flexible reinforcing material is used in the construction method, it becomes difficult to maintain its linearity. Therefore, when the reinforcing material is inserted after drilling, the contact or friction between the reinforcing material and the hole wall, the contact or friction between the spacer attached to the reinforcing material and the hole wall, or the collapse of the hole wall due to these. Therefore, there was a problem that it became difficult to insert the reinforcing material.

In addition, even if the insertion is completed, it is difficult to install a flexible reinforcing material on the center line of the drilling in the ground reinforcement earthwork that does not give prestress, so it was filled with grout and solidified. At that time, the flexible wire rod was arranged non-linearly in the fixing region, and there was a problem that a predetermined covering could not be secured between the reinforcing material and the hole wall.

In particular, in the construction method in which the conventional ground reinforcement earthwork is improved so that the reinforcing material has a stretchable region so that prestress can be introduced, the reinforcing material is not arranged on the center line of the drilling in the fixing region. There is a problem that a non-uniform stress distribution occurs at the time of tension, which makes it difficult to maintain a predetermined prestress.

An object of the present invention is to make it possible to install a flexible reinforcing material on the center line of a hole in a collapse prevention reinforcing body and a collapse prevention method for sloping land using the same.

In order to achieve the above object, the present invention provides the following configurations.
-Aspects of the present invention are a bearing material provided in a drilling hole formed up to an immovable ground through a moving soil mass in a ground on a sloping ground, and a bearing material provided on the surface layer of the ground, and the bearing pressure. In a collapse prevention reinforcing body for sloping terrain, which has a reinforcing material that is a wire rod that connects the material and the immovable ground and has flexibility.
With two or more spacers attached to the reinforcing material,
It has two or more guide wires pre-arranged in the drilling before inserting the reinforcing material into the drilling.
The spacer is characterized in that at least the same number of through portions as through the guide wire or fitting portions that fit with the guide wire are formed.
-In the above aspect, it is preferable that the reinforcing material has a stretchable region that is not integrated with the ground.
-Another aspect of the present invention is to make a hole in a sloping ground through a moving soil mass to an immovable ground, and to provide a bearing material on the surface layer of the ground and the immovable ground. In the method of inserting the reinforcing material in the collapse prevention reinforcement method for sloping terrain, which is connected by a reinforcing material which is a flexible wire rod.
After arranging two or more guide lines around the center line of the reinforcing material planned in the drilling, the reinforcing material to which two or more spacers are attached is inserted into the drilling.
At the time of inserting the reinforcing material, the guide wire is penetrated through the spacer formed with at least the same number of penetration portions or fitting portions as the guide wire, or the spacer is fitted with the guide wire. It is characterized by inserting a reinforcing material.
-In yet another aspect of the present invention, after the above-mentioned method of inserting the reinforcing material is performed, the grout is filled in the hole, and after the grout is cured, the reinforcing body is inserted through the bearing material. It is characterized in that it is fixed or a predetermined prestress is introduced into the reinforcing material via the pressure bearing material to be fixed.

The effects of the present invention are as follows.
1) Two or more spacers are attached to the flexible reinforcing material, and the spacers are penetrated by two or more guide wires pre-arranged in the drilling before inserting the reinforcing material into the drilling hole. Since it has a through portion or a fitting portion to be fitted, it is guided by a guide wire when the reinforcing material is inserted into the drilling hole, and the reinforcing material can be smoothly inserted without touching the hole wall.
2) Two or more guide wires are installed in advance in the drilled hole, and the two or more spacers attached to the reinforcing material have through portions or fitting portions for passing at least the same number of guide wires as the number of guide wires. Therefore, by appropriately setting the number of spacers according to the length of the reinforcing body, the flexible reinforcing material can be smoothly inserted and centered.
3) As a result, the flexible reinforcing material can be positioned linearly on the center line of the drilling, so that when the grout is injected, the grout is uniformly filled in the drilling, and the reinforcing material and the hole are filled. A predetermined cover can be secured between the wall and the wall.
4) When the moving soil mass moves after the grout solidifies, or when a tensile force acts when prestress is introduced into the reinforcing material, it is possible to avoid the occurrence of uneven stress distribution inside the fixing region, and it is possible to prevent the construction. Greatly improved quality.

5) PC steel stranded wire, which is a typical flexible material, has a problem that the cross-sectional area is smaller than that of reinforcing bars and rock bolt materials, and the adhesive force with grout is very small. By using the above, the shear strength is increased when the prestress is not introduced into the reinforcing material, and when the prestress is introduced into the reinforcing material, the adhesive force in the fixing region is increased and the tensile strength is improved.
6) Compared with the conventional spraying method frame construction, the collapse depth that can be deterred can be expanded from about 1 m to about 3 to 4 m because it has a large deterrent effect, and since the method frame disappears, it is possible to completely green the area. There is no need to assemble or cure the legal frame, and the construction period can be shortened significantly.
7) Compared with the general rebar insertion work of the conventional technology, prestress can be introduced because the PC rope stranded wire used in the ground anchor work is used, and the yield strength per unit area is greatly improved. It is possible to skip the setting pitch, shorten the construction period and improve economic efficiency.
8) When greening slopes such as slopes, a net-like body such as wire mesh or geogrid is placed on the entire slope, the collapse prevention reinforcement method for slopes of the present invention is applied, and a growth base is sprayed on it. If prestress is not introduced, a restraining work can be realized, and if prestress is introduced, a greening work having a function as a deterrent work can be realized.

FIG. 1 is a schematic cross-sectional view of a ground showing an outline of the present invention. FIG. 2 is a schematic enlarged cross-sectional view of FIG. 1, and shows an embodiment in particular when prestress is introduced. FIG. 3A shows a cross section taken along the line AA of FIG. 2, and FIG. 3B shows a cross section taken along the line BB of FIG. FIG. 4A is a front view of an embodiment of the spacer of the present invention, and FIG. 4B is a side view. FIG. 5A is a front view of another embodiment of the spacer of the present invention, and FIG. 5B is a side view.

Hereinafter, embodiments of the present invention will be described with reference to the drawings showing examples.
FIG. 1 is a schematic cross-sectional view of a ground showing an outline of the present invention. FIG. 2 is a schematic enlarged cross-sectional view of FIG. 1 (Note that FIG. 2 shows the dimensions in the direction perpendicular to the axial direction exaggerated, with some omissions in the axial length of the collapse prevention reinforcing body. ing).

FIG. 3A shows a cross section taken along the line AA of FIG. 2, and FIG. 3B shows a cross section taken along the line BB of FIG. FIG. 4A is a front view of an embodiment of the spacer of the present invention, and FIG. 4B is a side view. FIG. 5A is a front view of another embodiment of the spacer of the present invention, and FIG. 5B is a side view.

The collapse prevention reinforcing body for slopes of the present invention will be described with reference to FIGS. 1 to 5.
In FIGS. 1 and 2, a drilling hole 8 is drilled through the moving soil mass 3 to the immovable ground 4, a guide wire 9 is installed in the drilling hole 8, and then a reinforcing material 6 to which a spacer 7 is attached is inserted. An example is shown in which the grout 41 has been fixed through a predetermined step of injecting the grout 41.

The collapse prevention reinforcing body 10 includes a reinforcing material 6, two or more spacers 7 attached to the reinforcing material 6, and two or more guide wires 9 previously installed in the drilling hole 8 before inserting the reinforcing material 6. It has at least a grout 42 filled in the drilled hole 8 and a bearing plate 5 installed on the surface layer portion of the ground 1. In FIG. 2, as an example in the case of introducing prestress, a covering material 42 for covering the reinforcing material 6 is provided, but the covering material 42 is not essential.

The reinforcing material 6 is not particularly limited as long as it has a predetermined strength required by design and is flexible. However, a PC steel stranded wire having a total length that can be expanded and contracted is suitable. Further, as the PC steel stranded wire having an enhanced rust preventive effect, an unbonded PC steel stranded wire filled with a rust preventive agent at intervals of the PC steel stranded wire can also be used.

Further, when prestress is introduced into the reinforcing material 6, as illustrated in FIGS. 2 and 3, the reinforcing material 6 is covered with a covering material 42 such as polyethylene resin to prevent the grout 41 from adhering to the reinforcing material 6. , It is possible to secure an elastic region in which the reinforcing material 6 can expand and contract inside the covering material 42.

The wire diameter of the reinforcing material 6 is preferably 12.7 mm in the applicable range of the reinforcing bar reinforcing earthwork, and 15.2 mm or 17.8 mm in the intermediate region between the reinforcing bar reinforcing earthwork and the ground anchor work in consideration of strength and economy. Is.

The material of the guide wire 9 is not particularly limited as long as it is a linear wire having no flexibility. However, deformed reinforcing bars (about D10) are suitable. The number of guide lines 9 is preferably 2 to 6, and 4 lines shown in the examples are more preferable in consideration of workability and economy.

As shown in FIGS. 3, 4 and 5, the spacer 7 is provided with at least the same number of through portions 32 or fitting portions 31 as the number of guide wires 9 installed. Further, a hole 33 for the reinforcing member 6 to penetrate is formed in the center of the spacer 7. The shape of the spacer 7 is not limited to the illustrated example.

FIG. 4 shows an embodiment in which the fitting portion 31 is cut out on the outer circumference of a substantially cylindrical spacer 7 having a predetermined length in the axial direction. In the illustrated example, four fitting portions 31 are uniformly arranged in the circumferential direction of the spacer 7, and each fitting portion 31 extends over the entire length in the axial direction of the spacer 7. As shown in FIG. 5, a penetrating portion 32 may be provided between the central axis of the cylindrical spacer 7 and the peripheral surface. In the illustrated example, the four penetrating portions 32 are uniformly arranged in the circumferential direction of the spacer 7, and each penetrating portion 32 extends over the entire axial length of the spacer 7.

When the through portion 32 of the spacer 7 penetrates the guide wire 9 or the fitting portion 31 fits into the guide wire 9, the flexible reinforcing material 6 is guided linearly along the inflexible guide wire 9. .. As a result, the flexible reinforcing material 6 can be inserted into the drilling hole 8 without any trouble. The material of the spacer 7 is not particularly limited, and steel, resin, rubber, or the like can be used.

The number of spacers 7 to be attached to the reinforcing material 6 needs to be installed at least at two locations, a shallow portion and a deep portion. In order to satisfactorily insert the reinforcing material 6 into the drilled hole 8 and secure centering, it is preferable to install the reinforcing material 6 at at least three places including the middle part between the shallow part and the deep part. The number of spacers 7 is appropriately set according to the length of the reinforcing material 6.

An example of the construction method is as follows. Drilling holes 8 are drilled from the ground 1 on the slope to the immovable ground 4. Next, two or more guide lines 9 are arranged around the center line of the reinforcing member 6 scheduled in the drilling hole 8. It is desirable that the diameter of the drilled hole 8 is at least about 50 mm, assuming that four suitable D10 deformed reinforcing bars are used. The installation method of the guide line 9 is not particularly limited. For example, it is preferable to fix the tips of two or more guide wires 9 to the bottom member installed at the tip of the hole 8 by welding or the like. In that case, the positions of the tips of the two or more guide wires 9 coincide with the positions of the penetration portion 32 or the fitting portion 31 of the spacer 7 through which the guide wires 9 penetrate or fit in the subsequent process when viewed from the axial direction. To do so.

After the guide wire 9 is installed in the hole 8, the reinforcing material 6 to which the spacer 7 is attached in advance is inserted into the hole 8. When inserting the reinforcing material 6, the guide wire 9 is gradually inserted into the drilled hole 8 while penetrating the penetrating portion 32 of the spacer 7 or fitting the fitting portion 31 of the spacer 7.

When prestress is not introduced into the reinforcing material 6, when the insertion of the reinforcing material 6 is completed, the grout 41 is filled in the entire hole 8, and after the grout 41 is cured, the reinforcing material 6 is passed through the bearing material 5. To settle. Of course, it is also possible to insert the reinforcing material 6 to which the spacer 7 is attached in advance into the hole 8 after the grout 41 is injected into the hole 8 in advance.

When prestress is introduced into the reinforcing material 6, when the insertion of the reinforcing material 6 is completed, the grout 41 is filled in the entire hole 8, and after the grout 41 is cured, the reinforcing material 6 is passed through the bearing material 5. After introducing a predetermined prestress into the body (see FIG. 2).

In order to improve the filling property of the grout 41, it is preferable to attach an injection pipe to the reinforcing material 6 in advance so that the grout 41 is filled from the bottom portion in the drilled hole 8. These construction methods are the same as the conventional construction methods for ground reinforcement earthwork and ground anchor work.

In the embodiment of FIG. 2, the collapse prevention reinforcing body 10 is prestressed through the bearing member 5 installed on the ground 1, and the head of the reinforcing member 6 is fixed by the wedge 21. .. The fixing method is not limited to wedge fixing, and various methods such as condominium processing of the reinforcing material 6 and nut fixing can be adopted. Further, the head of the reinforcing material 6 is covered with a cap 22 so that the inside can be filled with rust preventive oil. In some cases, a legal frame work or a precast pressure receiving plate may be used together between the ground 1 and the bearing material 5, but whether or not to combine these structures is appropriately determined according to the site. ..

As an example in which the present invention works effectively, when greening a slope such as a slope, a net-like body such as a wire mesh or a geogrid is stretched over the entire slope, and the collapse prevention reinforcement method for the slope of the present invention is applied. Spray the growth base on it. As a result, it is possible to realize a greening work having a function as a restraining work when prestress is not introduced and as a deterrent work when prestress is introduced.

Further, the same effect can be obtained by attaching a vegetation net or a vegetation mat to the slope, then attaching a net-like body to the entire slope, and applying the collapse prevention reinforcement method for slopes of the present invention to green the slope.

In the construction method using the above-mentioned net-like body together, when prestress is introduced into the reinforcing material 6 of the present invention, tension of 100 kN / piece is possible, so that the ground is reinforced by inserting the conventional deformed reinforcing bars D19 and D22. Compared to earthwork, the deterrent collapse depth can be expanded to about 4 m.

Specifically, it is assumed that the depth that can be suppressed is about 4 m when weathered rocks can be fixed, and about 3 m when sediments are fixed. The deterrent force required for slope stability is shared by the reinforcing material 6, and the strength can be increased as compared with the conventional technique, so that the casting pitch can be increased.

In addition, the structure will be shared by a net-like body with appropriate strength against the collapse of the ground, which is a concern due to the large casting pitch. As a result, in particular, by adopting a reinforcing material having a wing-shaped portion on the head as shown in Japanese Patent Application Laid-Open No. 2015-175118 by the present applicant, the casting pitch can be expanded from approximately 1 m to approximately 2 m. Is possible.

1 Ground 2 Sliding surface 3 Moving soil mass 4 Immovable ground 5 Supporting material 6 Reinforcing material 7 Spacer 8 Drilling hole 9 Guide wire 10 Collapse prevention reinforcing body 21 Wedge 31 Fitting part 32 Penetration part 33 Center hole 41 Grout 42 Covering material

Claims (4)

The bearing material provided in the surface layer of the ground, which is installed in a hole drilled to the immovable ground through the moving soil mass in the ground of the sloping ground, and the bearing material and the immovable ground. In a sloping ground collapse prevention reinforcing body having a reinforcing material which is a wire rod which is flexible and connects the above
With two or more spacers attached to the reinforcing material,
It has two or more guide wires pre-arranged in the drilling before inserting the reinforcing material into the drilling.
The spacer is a collapse prevention reinforcing body for sloping terrain, characterized in that at least the same number of through portions as through the guide wire or fitting portions that fit with the guide wire are formed. The collapse prevention reinforcing body for slopes according to claim 1, wherein the reinforcing material has a stretchable region that is not integrated with the ground. A hole is drilled through the moving soil mass to the immovable ground, and the bearing material provided on the surface layer of the ground and the immovable ground are made of a flexible wire rod. In the method of inserting the reinforcing material in the collapse prevention reinforcement method for sloping terrain, which is connected by a certain reinforcing material,
After arranging two or more guide lines around the center line of the reinforcing material planned in the drilling, the reinforcing material to which two or more spacers are attached is inserted into the drilling.
At the time of inserting the reinforcing material, the guide wire is penetrated through the spacer formed with at least the same number of penetration portions or fitting portions as the guide wire, or the spacer is fitted with the guide wire. A method of inserting a reinforcing material, which comprises inserting a reinforcing material. After performing the method for inserting the reinforcing material according to claim 3,
After filling the holes with grout and curing the grout,
A collapse prevention reinforcement method for sloping terrain, characterized in that the reinforcing body is fixed through the bearing material, or a predetermined prestress is introduced into the reinforcing material through the bearing material to fix the reinforcing body.

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