JP7028817B2 - Slope collapse prevention reinforcement body and slope collapse prevention reinforcement method using this - Google Patents

Description

The present invention relates to a collapse prevention reinforcing body that prevents the collapse of slopes. In particular, the drilling length, 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, is approximately 3 to 10 m. (Although it will be described later, more preferably, the present invention relates to a slope collapse prevention reinforcing body for a region having a drilling length of about 5 to 10 m) and a slope collapse prevention construction method using the same.

Construction methods (Patent Documents 1 to 3, etc.) for providing a collapse prevention reinforcing body to prevent collapse of slopes are roughly classified into ground anchor construction and ground reinforcement earthwork (also referred to as reinforcing bar insertion construction and rock bolt construction).

Ground anchor construction is carried out by drilling a hole in a sloped ground through a moving soil mass to an immovable ground (also called a settlement area). 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 an elastic 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 sloped ground 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 integrated with the immovable ground via 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 can freely expand and contract. 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. 11-343800 Japanese Unexamined Patent Publication No. 2007-107372

The existing slope stabilization works are targeted for drilling lengths of approximately 2 to 5 m for ground reinforcement earthworks and approximately 7 to several tens of meters for ground anchor works. Therefore, when the slip surface is deeper than about 2 to 5 m, the drilling length is about 3 to 10 m, and there is a problem that the ground reinforcement earthwork cannot be adopted.

Further, in this case, if a ground anchor construction targeting about 7 m or more is applied, a function of preventing collapse can be obtained, but there is a problem that it is economically expensive, that is, it becomes an over-designed.

Further, when the ground reinforcement earthwork is applied when the drilling length is about 3 to 10 m, there is a problem that the plate of the bearing plate and the nut for fastening the reinforcing material are lifted due to the displacement of the ground. Therefore, in a boundary region with a drilling length of approximately 3 to 10 m, more preferably in a boundary region with a drilling length of approximately 5 to 10 m, a construction method that can demonstrate the functions of both ground reinforcement earthwork and ground anchor construction, that is, bending. There has been a demand for a collapse prevention reinforcement body for slopes and a collapse prevention reinforcement method for slopes, which have excellent shear resistance, maintain prestress and do not cause ground displacement, and are economical.

An object of the present invention is to provide a collapse prevention method suitable for a sloped ground in a boundary region between a ground anchor work and a ground reinforcement earthwork.

In order to achieve the above object, the present invention provides the following configurations.
-Aspects of the present invention include a bearing material provided in a drilling hole that penetrates a moving soil mass in a sloped ground and reaches an immovable ground, and is provided on the surface layer of the ground, and the bearing material and the above. In a sloped slope collapse prevention reinforcing body having a reinforcing material formed of an elastic region that is connected to an immovable ground and is not integrated with the ground, and a protective material that is an outer pipe of the reinforcing material.
The reinforcing material has a flexible wire having a stretchable overall length and a covering material covering the wire to secure a stretchable region over substantially the entire length, and does not have flexibility with the reinforcing material. The protective material is fixed to each other at the tip in the axial direction and integrated.
The length of the drilled hole is 3 to 10 m, the protective material is divided into at least two in the axial direction, and each of the divided protective materials is generated when prestress is applied to the reinforcing material. It is characterized in that an elastic body having an elastic structure capable of absorbing the plastic displacement of the immovable ground is bonded to each protective material .
-In the above embodiment, it is preferable that the protective material located on the moving soil mass side of the divided protective materials is a carbon steel pipe for piping.
-In the above embodiment, it is preferable that the elastic body is a hard rubber nipple and has a grout injection hole and an exhaust hole penetrating in the axial direction.
Another aspect of the present invention is a collapse prevention reinforcement method for slopes, wherein the collapse prevention reinforcement body of any one of the above aspects is inserted into the drilling hole to fill the grout, and after the grout is cured, the said It is characterized in that a predetermined prestress is applied to the reinforcing material via the pressure bearing material to fix the reinforcing material.

The effects of the present invention are as follows.
1) The present invention is a high-strength ground-reinforcing earthwork having a stretchable region and sustaining prestress. As a result, it is possible to prevent the phenomenon that the plate and nut of the bearing plate are lifted, which occurs in the conventional frame construction + ground reinforcement earthwork, which is a conventional collapse prevention construction method.
2) In the present invention, since the permissible yield strength per collapse prevention reinforcing body is large, the placement interval (approximately 1.5 to 2.0 m) of the conventional ground reinforcement earthwork is expanded to about 3.0 m. Can be done.
3) By using a carbon steel pipe for piping (SGP steel pipe) with a large moment of inertia of area compared to the conventional ground reinforcement earthwork that uses deformed reinforcing bars (D19 to D29) as the reinforcing material, it is resistant to bending and shearing. Resistance is greatly improved. In particular, regarding the resistance to the moment, since the tension force acts on the steel pipe which is the outer pipe which is the protective material via the PC rope twisted wire, the structure is similar to that of a PC pile having a small diameter.
4) It is possible to construct up to an area with a length of about 5 to 10 m, which was not applicable to the ground reinforcement earthwork (length approximately 2 to 5 m).
5) Since it is possible to construct the boundary area (a range of approximately 5 to 7 m) between the ground anchor work and the ground reinforcement earthwork, a small-scale collapse (depth of about 3 m) that is the target of the ground reinforcement earthwork will be constructed. ) Can be expanded to a medium-scale collapse (depth of about 7 m).
6) By connecting the protective material (outer pipe) divided into at least two with an elastic body, a slope stabilization work dedicated to the boundary area, which has a ground anchoring function and a ground reinforcement earthworking function, has been realized. ..
7) Since the elastic body that connects the protective materials absorbs the plastic displacement in the fixing region, the influence on the grout in the expansion / contraction region (crack generation, etc.) can be reduced.
8) The SGP steel pipe constituting the protective material corresponding to the fixing region of the anchor fixing body is subjected to screw processing inside and outside, so that the adhesion resistance of grout is increased.
9) The SGP steel pipe constituting the protective material corresponding to the fixing region of the anchor fixing body is fixed to the reinforcing material at the tip thereof, so that a compressive force acts on the inner grout. Therefore, it is possible to greatly suppress the occurrence of cracks, which is a concern in the friction-pull type ground anchor construction.
10) By providing an inner grout inside the protective material, it becomes possible to create an anchor fixing body in the ground anchor work.
11) The grout can be made into an inner grout by using a structure in which an opening is provided on the side surface of the protective material located on the immovable ground side or a structure in which an opening is provided in the fixing member at the tip of the protective material on the immovable ground side. Outer grout can also be performed at the same time by simply injecting from the injection pipe.
12) Since the number of parts constituting the reinforcing material is smaller than that of the ground anchor, it is easy to assemble on-site even if it is not manufactured in the factory in advance.
13) Since materials other than elastic materials can be easily procured on the market, they can be widely applied as slope protection works without limiting the construction area.

FIG. 1 is a schematic cross-sectional view of a ground showing an outline of an embodiment of the present invention. 2 (a) is a schematic enlarged cross-sectional view of FIG. 1, and FIG. 2 (b) is a cross-sectional view showing a portion of the reinforcing material and the protective material of (a). 3 (a) shows the AA cross section of FIG. 2 (a), (b) shows the BB cross section of FIG. 2 (a), and (c) shows the CC cross section of FIG. 2 (a). Is shown. FIG. 4A is a side view of an embodiment of the elastic body of the present invention, and FIG. 4B shows an end face of FIG. 4A. FIG. 5 is a side view of another embodiment of the elastic body of the present invention.

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 an embodiment of the present invention. 2A is a schematic enlarged cross-sectional view of FIG. 1, and FIG. 2B is a cross-sectional view showing a portion of the reinforcing material and the protective material of FIG. 1 (Note that FIG. 2 is a shaft of a collapse prevention reinforcing body. The length in the direction is partially omitted, and the dimension in the direction perpendicular to the axial direction is exaggerated).

3 (a) shows the AA cross section of FIG. 2 (a), (b) shows the BB cross section of FIG. 2 (a), and (c) shows the CC cross section of FIG. 2 (a). Is shown. FIG. 4A is a side view of an embodiment of the elastic body of the present invention, and FIG. 4B shows an end face of FIG. 4A. (C) is a side view of another embodiment of the elastic body of the present invention. FIG. 5 is a side view of another embodiment of the elastic body of the present invention.

The collapse prevention reinforcing body for slopes of the present invention will be described with reference to FIGS. 1 to 5.
As shown in FIG. 1, a hole 11 is drilled in a sloped ground through a moving soil mass 3 to reach an immovable ground 4, and a slope collapse prevention reinforcing body 12 of the present invention is inserted into the hole 11. It has been established through a predetermined process. The position of the slip surface 2 is an example and is not limited to this portion.

The collapse prevention reinforcing body 12 has a double structure of a reinforcing material 6 and a protective material 7 which is an outer pipe thereof. The reinforcing material 6 is a flexible wire rod, the protective material 7 is a non-flexible circular pipe material, and there is a certain distance between the outer peripheral surface of the reinforcing material 6 and the inner peripheral surface of the protective material 7. It is provided. The overall lengths of the reinforcing material 6 and the protective material 7 in the axial direction are almost the same, but the reinforcing material 6 is longer and may protrude by a predetermined length from the head and the tip of the protective material 7. can.

The protective material 7 is divided into at least two pieces in the axial direction. In the illustrated example, it is divided into a protective material 7a on the immovable ground 4 side and a protective material 7b on the moving soil mass 3 side. The divided protective materials 7a and 7b are connected to each other via the elastic body 8. When the protective material 7 is divided into three or more, each protective material is bonded to each other via two or more elastic bodies 8. Further, the tip portion of the reinforcing material 6 is fixed and integrated with the tip portion of the protective material 7 by an appropriate fixing member 9.

The elastic body 8 is a substantially columnar shape having a predetermined length in the axial direction and having a diameter at least equivalent to that of the protective material 7. The elastic body 8 has a hole through which the reinforcing material 6 is penetrated in the axial direction. Further, the elastic body 8 is formed with an injection pipe hole 41 for passing the grout injection pipe 23 in the axial direction and an exhaust hole 42 for air.

For example, as shown in FIG. 2B, the fixing member 9 closes the opening at the tip of the protective material 7a on the immovable ground 4, and the tip of the reinforcing member 6 penetrates the fixing member 9 and ends. It is fixed by a wedge 15 via the head 14. The method of fixing the tip portion is not limited to the illustrated example. In this way, the reinforcing material 6 and the protective material 7 (protective materials 7a, 7b and the elastic body 8) are integrated, and the injection pipe 23 is provided in advance.

In general, it is efficient to carry the collapse prevention reinforcing body 12 to the site in which the reinforcing material 6 and the protective material 7 are fixed and integrated at the tip portion in advance at a factory or the like. However, materials other than elastic bodies can be assembled on-site because they are easily procured on the market. Further, a compression type anchor can be obtained by providing a restraint at the tip where the reinforcing material 6 and the protective material 7 are fixed and integrated at the tip (if the restraint is not provided, the friction type). Become an anchor).

As shown in FIG. 2A, the inner grout 22 is filled in the space between the reinforcing material 6 and the protective material 7 over the entire length of the collapse prevention reinforcing body 12, and the protective material 7 and the wall of the drilling 11 are formed. The outer grout 21 is filled in the space between them.

The reinforcing material 6 may be made of any material as long as it has a predetermined strength required by design and is flexible. A PC steel stranded wire having a total length that can be expanded and contracted is suitable. Further, the reinforcing material 6 of the present invention is covered with a covering material 17 such as polyethylene resin over substantially the entire length. As a result, even after the outside of the covering material 17 is hardened by grout, an expansion / contraction region in which the reinforcing material 6 can be expanded and contracted is secured over substantially the entire length of the reinforcing material 6.

Since the reinforcing material 6 can have a substantially total length as a stretchable region by covering the substantially total length with a covering material 17 such as polyethylene resin, it is possible to cope with a larger displacement as compared with the conventional ground reinforcement earthwork. can.

Further, as the PC steel stranded wire having a further enhanced rust preventive effect, an unbonded PC steel stranded wire in which the gap between the PC steel stranded wires is filled with a rust preventive agent can also be used. The wire diameter of the reinforcing material 6 is preferably 15.2 mm or 17.8 mm in terms of strength and economy, considering the application to the intermediate region between the ground reinforcement earthwork and the ground anchor work to which the present invention is applied. be.

The material of the protective material 7 is not particularly limited as long as it has a predetermined strength required by design. However, dimple steel pipes and carbon steel pipes for piping (SGP steel pipes) are suitable because at least the protective material 7b on the side of the moving soil mass 3 has a function as a small-diameter steel pipe pile having a large moment of inertia of area. In particular, SGP steel pipe has high versatility and is also effective in terms of economy. When the SGP steel pipe is used, the moment of inertia of area is about 10 times or more that of the reinforcing bar (PC steel rod D22) used in general ground reinforcement earthwork, and the bending and shearing performance can be significantly improved.

As a result, when the allowable load is calculated, the PC steel rod D22 is 75 kN / piece, whereas the collapse prevention reinforcing body 12 of the present invention protects the unbonded PC steel stranded wire on the flexible reinforcing material 6. When the SGP steel pipe is used for the material 7, the value is 156 to 232 kN / piece, which can be improved to 4 times that of the PC steel rod D19 and 3 times that of the PC steel rod D22.

In the collapse prevention reinforcing body 12 of the present invention, the inner grout 22, the protective material 7, and the outer grout 21 form a fixing region, while the reinforcing material 6 constitutes an expansion / contraction region over substantially the entire length. The fixing region and the expansion / contraction region are separated by the covering material 17.

The elastic body 8 serves as a cushioning material that absorbs the plastic displacement of the fixing region generated when the reinforcing material 6 is prestressed. It does not matter as long as it is a material that satisfies the function. However, the hard rubber used for the seismic isolation device or the like is suitable.

Further, the elastic body 8 needs to be connected to the protective material 7a on the immovable ground 4 side and the protective material 7b on the moving soil mass 3 side. For example, as shown in FIG. 4 (a) (reinforcing material 6 with a covering material 17 is also shown for reference), it is more preferable to use a screwed hard rubber nipple. In addition to rubber, any elastic structure that can absorb displacement, such as steel being processed into a bellows, may be used.

As shown in the cross-sectional views of FIGS. 3A to 3C, the elastic body 8 is made of polyethylene into which grout is injected, in addition to a hole through which a reinforcing material 6 coated with a covering material 17 such as polyethylene resin passes. An injection pipe hole 41 through which the injection pipe 23 and the like are passed and an exhaust hole 42 for discharging the internal air at the time of grout injection are provided. As a result, the elastic body 8 acts as a packer for the inner grout 22 when the grout is pressure-injected into the fixing region via the injection pipe 23, and the effect of pressure-injecting the inner grout 22 can be obtained.

Further, as shown in FIG. 5, the diameter of the elastic body 8 is made larger than that of the protective material 7 so that the grout is substantially in contact with the wall of the drilling 11 to press the grout to the fixing region via the injection pipe. When injecting, it acts as a packer for the outer grout 21, and the effect of pressurizing the outer grout 21 can be obtained.

In the construction, the ground 1 of the slope is drilled to the fixed ground or the immovable ground 4, the collapse prevention reinforcing body 12 of the present invention is inserted, and the injection pipe 23 provided in advance in the collapse prevention reinforcing body 12 is used for the construction. It is completed by filling the grout, and after the grout is cured, applying a predetermined prestress to the bearing material 5 to fix the grout.

For drilling and injecting grout, the general method used for the existing ground reinforcement earthwork and ground anchor work can be appropriately used. Further, as the grout, a solidifying agent typified by cement milk can be appropriately used.

In an example of the grout filling method, the inner grout 22 may be performed by inserting the collapse prevention structure 12 of the slope of the present invention after injecting the grout into the drilling 11 in advance according to the existing construction method. It is possible.

In another example of the grout filling method, a structure in which an opening is provided on the side surface of the protective material 7a located on the immovable ground side, or an opening is provided in the fixing member 9 at the tip of the protective material 7 on the immovable ground side. By adopting the provided structure, the outer grout 21 on the outer side of the protective materials 7a and 7b can be performed at the same time only by injecting the grout from the injection pipe 32 for the inner grout. When an opening is provided on the side surface of the protective material 7a located on the immovable ground side, a plurality of holes (for example, about 10 mm in diameter) may be provided in the vicinity of the tip. When the fixing member 9 is provided with an opening, the structure may have a similar gap.

The grout injection pipe 23 needs to have a structure that can be injected at least deeper than the elastic body 8. Considering the efficient emphasis of grout on the anchorage area, it is desirable to pipe as far as possible to the tip.

FIG. 3A shows a cross section of the moving soil mass 3 side after construction, and FIG. 3B shows a cross section of the immovable ground 4 side. By injecting grout through an injection pipe that is piped from the elastic body 8 of the collapse prevention reinforcing body 12 of the present invention to the fixed ground deeper or the immovable ground 4 side, the outer grout 21 and the inner side of the protective material 7 are injected. The inner grout 22 is filled.

In the embodiment of FIG. 2, the collapse prevention reinforcing body 12 has a pressure receiving plate (not shown) constructed on the surface of the ground 1, and is prestressed via the pressure bearing material 5 installed on the pressure receiving plate. Is given and is fixed by the wedge 15. The fixing method is not limited to wedge fixing, and various methods such as mansion processing of the reinforcing material and nut fixing can be adopted. Further, whether or not to combine a structure similar to a pressure receiving plate in addition to the pressure bearing material 5 is a design matter and is determined according to the site.

The protective material 7a deeper than the elastic body 8, that is, the protective material 7a on the immovable ground 4 side forms a fixing body by the inner grout, and the protective material 7b on the immovable ground 4 side acts as a load-bearing body in the ground anchor work. On the other hand, the protective material 7b shallower than the elastic body 8, that is, the protective material 7b on the moving soil mass 3 side, exerts a function as a small-diameter steel pipe pile of a PC structure by the inner grout and the outer grout, so that displacement does not occur. In the conventional construction method, the protective material 7 is merely an outer pipe and functions as a protective material for drilling holes 11 and as a water blocking material. However, since the protective material 7 is provided with a function as a collapse suppressing material by the present invention, bending is performed. And a collapse prevention reinforcement structure with excellent shear performance is realized.

As shown in the figure of the end face of the elastic body 8 in FIG. 4 (b), the reinforcing material 6 is drawn slightly offset from the center, but the deviation of the center of the dimensions shown in the figure does not matter. However, if it is desired to improve this, as a variation of construction, in order to maintain the linearity of the reinforcing material 6, the reinforcing material 6 is centered by performing a primary tension immediately after filling the grout and introducing a predetermined prestress after the grout is hardened. It can also be located at.

1 Ground 2 Sliding surface 3 Moving soil mass 4 Immovable ground 5 Supporting material 6 Reinforcing material 7 Protective material 8 Elastic body 9 Fixing material 11 Drilling hole 12 Collapse prevention reinforcing body 14 End head 15 Wedge 16 Head head 17 Covering material 21 Outer grout 22 Inner grout 23 Injection pipe 41 Injection pipe hole 42 Exhaust hole

Claims (4)

It is installed in a drilling hole that penetrates a moving soil mass in a sloped ground and reaches the immovable ground, and connects the bearing material provided on the surface layer of the ground with the bearing material and the immovable ground. It also has a reinforcing material formed with an elastic region that is not integrated with the ground, and a protective material that is an outer pipe of the reinforcing material, and the reinforcing material has flexibility in its entire length that can be expanded and contracted. The wire rod has a covering material covering the wire rod to secure an elastic region over substantially the entire length, and the reinforcing material and the non-flexible protective material are fixed to each other at an axial tip portion. In the collapse prevention reinforcement of slopes that are integrated together
The drilling length is 3 to 10 m, and the drilling length is 3 to 10 m.
The protective material is divided into at least two in the axial direction, and each of the divided protective materials has an elastic structure capable of absorbing the plastic displacement of the immovable ground generated when the reinforcing material is prestressed. A collapse prevention reinforcing body for slopes, characterized in that an elastic body having an elastic body is bonded between the protective materials . The collapse prevention reinforcing body for slopes according to claim 1, wherein the protective material located on the moving soil mass side among the divided protective materials is a carbon steel pipe for piping. The collapse prevention reinforcing body for slopes according to claim 1 or 2, wherein the elastic body is a hard rubber nipple and has a grout injection hole and an exhaust hole penetrating in the axial direction. The collapse prevention reinforcing body according to any one of claims 1 to 3 is inserted into the drilling hole to fill the grout, and after the grout is cured, the reinforcing material is subjected to a predetermined prestress via the pressure bearing material. A method of reinforcement to prevent collapse of slopes, which is characterized by giving and fixing.

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