JP2019044571A - Reinforcement method - Google Patents

Abstract

To provide a reinforcement method which can secure a sufficient peripheral surface frictional resistance even though a bolt length is short, and can also prevent peeling between a steel member and a solidified injection material.SOLUTION: A reinforcement method includes: a step of drilling a boring hole (H); a step of inserting a hollow core material (1) formed with a through port (1A: for example, slit, hole or the like) into a boring hole (H); and a step of supplying an injection material (C: for example, grout material) to a hollow part of the core material (1), and injecting (discharging) the injection material from the through port (1A) into the ground.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a reinforcing method for reinforcing a slope with a lock bolt, for example.

For example, when rock bolting is applied to the embankment slope, the bolt length may be set long to ensure a circumferential friction resistance of a predetermined value or more. However, if the bolt length is long, the construction cost increases accordingly and there is a problem in economic efficiency.
In addition, when injecting the injection material (grouting material), so-called “casing pressure injection” may be performed to form a region where the injection material is injected at the tip of the underground side of the rock bolt. If such a construction method is used, when a pulling force is applied to the lock bolt, the region into which the injection material has been injected exhibits a resistance force and can counter the pulling force.
However, the friction between the steel rock bolt and the injection material becomes insufficient, and when a pulling force is applied, only the steel lock bolt may be peeled off from the solidified injection material and pulled out to the ground side.

As another conventional technique, there is a method of creating a reinforcing material having a step of injecting the injected material under pressure (see Patent Document 1), and there is also a technology of creating a compacted sand pile for improving the ground in the vertical direction ( Patent Document 2), there is a slope stabilization technique that improves the earthquake resistance and rain resistance of a soil structure by a pressure injection type rod-shaped reinforcement (Patent Document 3).
However, none of these conventional techniques is aimed at ensuring the peripheral frictional resistance as described above and preventing the steel member from being separated from the solidified injection material.

JP 2015-110892 A Japanese Patent No. 59509797 Japanese Patent Laid-Open No. 2006-53273

  The present invention has been proposed in view of the above-mentioned problems of the prior art, and even if the bolt length is shortened, sufficient peripheral frictional resistance can be secured, and solidified with a steel member. The object is to provide a reinforcing method capable of preventing peeling from the injection material.

The reinforcing method of the present invention includes a step of drilling a bore hole (H) (for example, by casing drilling),
Inserting a hollow core material (1) in which a through-hole (1A: for example, a slit or a hole) is formed into a boring hole (H);
An injection material (C: for example, a grout material) is supplied to the hollow portion of the core material (1) and injected (discharged) into the ground from the through-hole (1A).

In the present invention, a plurality of the through holes (1A) are formed,
In the step of injection (discharge) into the ground, the injection material (C) is preferably injected (discharge) from all the through-holes (1A).
Alternatively, in the present invention, a plurality of through-holes (1A) of the core material (1) are formed,
The core material (1) is accommodated in the casing (3) inserted into the boring hole (H),
In the step of injecting (discharging) into the ground, the casing (3) is moved (pulled out) stepwise in the axial direction of the boring hole (H), so that a part not surrounded by the casing (3) The injection material (C) is injected (discharged) from only the through-hole (1A) of the casing, and the injection (discharge) from the through-hole (1A) surrounded by the casing (3) is the casing (3) surrounding the through-hole. It is also possible to have a process that is blocked by.

In the present invention, a plurality of the through holes (1A) are formed,
Injecting (discharging) into the ground is performed by inserting an injection material discharge pipe (2: packer tube) having a packer (2A) and an injection material discharge port (2B) into the core material (1), and discharging the injection material. Position the injection material discharge port (2B) of the pipe (2) at a predetermined through port (1AA: a through port through which the injection material C should be injected or discharged) and expand the packer (2A), It is preferable to inject (discharge) the injection material (C) only from the injection material discharge port (2B) of the injection material discharge pipe (2) and the through-hole (1AA) positioned.

  In the present invention, a highly viscous injection material (an injection material having a higher viscosity than an injection material injected by secondary injection, for example, plastic grout) is supplied to the hollow portion of the core material (1) from the through-hole (1A). It is possible to include filling the casing (3).

  In the present invention, the core material (1) preferably has a shape in which a plurality of types (for example, two types) of rotating bodies (1-1, 1-2: for example, cylindrical shapes) having different diameters are alternately connected. .

In carrying out the present invention, in the step of injecting (discharging) into the ground, it is preferable that the ground-side end portion of the boring hole (H) is sealed with a sealing material (4: mouth seal material, for example, mouth packer).
In carrying out the present invention, it is preferable to control the range (injection range) in which the injection material (C) is injected into the ground by changing the cross-sectional area (size) of the through holes (1A, 1AA). .

According to the present invention having the above-described configuration, since there are regions (R1 to R4: see FIG. 1) into which the injection material is injected by pressure injection, a force to collapse the slope is generated, and the lock bolt Even if a force for pulling out (10) is applied, the regions (R1) to (R4) filled with the injection material (C) and solidified are resisted and the lock bolt (10) is prevented from being pulled out. Thus, the slope can be prevented from collapsing.
At that time, the regions (R1) to (R4) into which the injection material (C) is injected extend irregularly on the side of the lock bolt (10) in the direction perpendicular to the longitudinal direction. A large resistance force is generated against the force pulling (pulling) (10) to the ground side.
As a result, the circumferential frictional resistance can be improved without increasing the bolt length of the lock bolt (10).

Moreover, since a through-hole (1A: for example, a slit or a hole) is formed in the core material (1), and the injection material (C) is discharged from the through-hole (1A), the solidified injection material (C) passes through the through-hole. Since the region outside the core material (1) and the region inside the core material (1) are integrated through the mouth (1A), the solidified injection material (C) and the core material (1) are inseparably integrated. Become.
Therefore, even if the force which tries to pull out the core material (1) to the ground side acts, the region outside the core material (1) and the region inside the core material (1) are connected via the through-hole (1A). The integrated solidified injection material (C) prevents only the core material (1) from being pulled out to the ground side.

In the present invention, in the step of injecting (discharging) into the ground, the injection material (C) is injected (discharged) only from a part of the through holes (1A) not surrounded by the casing (3), and the casing (3) Injecting (discharging) from the through-hole (1A) surrounded by the ground has a step of being blocked by the casing (3) surrounding the through-hole, for example, in a stepwise and stable manner from the ground side Reinforcement can be applied.
Further, in the step of injection (discharge) into the ground, the injection material discharge port (2B) of the injection material discharge pipe (2) is positioned at a predetermined through-hole (1AA) of the core material (1), and the positioning is performed. If the injection material (C) is injected (discharged) only from the through-hole (1AA), the ground area can be reinforced with emphasis on the area that is highly necessary from the ground conditions.
Further, in the step of injecting (discharging) into the ground, an injection material discharge pipe (2: packer tube) having a packer (2A) and an injection material discharge port (2B) is inserted into the core material (1) and injected. The injection material discharge port (2B) of the material discharge pipe (2) is positioned at a predetermined through port (1AA: through port through which the injection material C should be injected or discharged) and the packer (2A) is expanded. If the injection material (C) is injected (discharged) only from the injection material discharge port (2B) of the injection material discharge pipe (2) and the positioned through port (1AA), only from the specific through port (1AA). Since the injection material (C) is injected (discharged), it is possible to inject the injection material (C) in a highly accurate and focused manner in a highly necessary region, thereby performing more efficient ground reinforcement.

Further, prior to the step of injecting the injection material (C) into the ground (secondary injection), the primary injection is performed in the hollow portion of the core material (1) (higher than the injection material used in the secondary injection). If an injection material (for example, plastic grout) is supplied and filled into the casing (3) from the through-hole (1A), the plastic grout is compared with the injection material (C) used for secondary injection, for example. Since it is a highly viscous fluid, after filling in the casing 3 (that is, in the bore hole H), it remains in the bore hole (H) for a long time.
When the boring hole (H) is filled with an injection material (for example, a plastic grout material) having a higher viscosity than the injection material (C) used in the secondary injection, the injection material used in the secondary injection. Unlike the case where the same injection material (C) as (C) is filled by primary injection, there is no need to wait for secondary injection (injection of injection material (C) into the ground) until the plastic grout material is cured. Therefore, the construction period can be shortened.
Further, when the plastic grout is filled in the borehole (H), the plastic grout remains in the borehole (H) for a long time, and the injection range can be controlled by performing limited injection at the time of secondary injection.

In the present invention, the core material (1) has a shape in which a plurality of types (two types in FIG. 2) of rotating bodies (1-1, 1-2, for example, a cylindrical shape) having different diameters are alternately connected. For example, since the outer peripheral side region of the rotating body (1-2) having a large radial dimension has a shape protruding radially outward, the periphery of the core material (1) is filled with the injection material (C) and solidified. The outer peripheral side region becomes a resistance, and the core material (1) can be prevented from being pulled out. This also leads to an improvement in the peripheral frictional resistance of the lock bolt (10).
In addition, even if the injection material (C: for example, grout material) flows out or escapes to the ground side along the outer peripheral surface of the core material, the outer peripheral edge of the core material (1) intermittently protrudes radially outward. Therefore, the injection material (C) is prevented from running away to the ground side.

  In the present invention, the range (injection range) in which the injection material (C) is injected into the ground can be controlled by changing the cross-sectional area (size) of the through holes (1A, 1AA). Therefore, the injection material (C) is injected into the ground by appropriately setting the size (cross-sectional area) of the through holes (1A, 11A: for example, slits and holes) formed in the core material (1). The range (injection range) can be controlled.

It is explanatory drawing which shows the state which implemented 1st Embodiment of this invention and reinforced the slope with the lock bolt. It is explanatory drawing which shows an example of the core material used by embodiment of illustration. It is explanatory drawing which shows 1 process of 1st Embodiment. It is explanatory drawing which shows the process following the process shown in FIG. 3 in 1st Embodiment. It is explanatory drawing which shows the process of following the process shown in FIG. 4 in 1st Embodiment. FIG. 6 is an explanatory diagram showing a step that follows the step shown in FIG. 5 in the first embodiment. FIG. 7 is an explanatory diagram showing a step that follows the step shown in FIG. 6 in the first embodiment. In 2nd Embodiment, it is explanatory drawing which shows the process following the process shown in FIG. FIG. 9 is an explanatory diagram showing a step that follows the step shown in FIG. 8 in the second embodiment. FIG. 10 is an explanatory diagram showing a step that follows the step shown in FIG. 9 in the second embodiment. In 2nd Embodiment, it is explanatory drawing which shows the process following the process shown in FIG.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
First, a first embodiment of the present invention will be described with reference to FIGS.
In FIG. 1 showing a state in which the slope is reinforced by the reinforcing method of the first embodiment, a lock bolt 10 is formed by an injection material C injected from the core material 1 into the ground by the steps described in FIGS. Has been. And the lock bottle 10 has the area | regions R1-R4 formed in the side, and the area | regions R1-R4 extend the side of the lock bottle 10 irregularly at right angles to a longitudinal direction.

In FIG. 1, the lock bolt 10 includes portions extending in the regions R <b> 1 to R <b> 4. Therefore, even if a force for pulling out the lock bolt 10 (force for pulling out the lock bolt 10) acts, the injection material C The resistance of the regions R1 to R4 filled with the grout material (for example, grout material) can prevent the lock bolt 10 from being pulled out, thereby preventing the slope from collapsing.
Therefore, even if the length of the lock bolt is not increased, the presence of the regions R1 to R4 improves the peripheral frictional resistance of the lock bolt 10.

When injecting the injection material C, since the injection material is discharged to the ground from the through-hole 1A (slit, FIG. 2) formed in the core material 1, the solidified injection material C is the core material through the slit 1A. The outer region of 1 and the inner region of the core are integrated. Here, the through-hole 1 </ b> A is not limited to a slit, and may be a circular or oval hole, or a hole having another shape. In other words, the shape of the through-hole 1A is not particularly limited.
Therefore, even if a force to pull the core material 1 to the ground side acts, the outer region of the core material 1 and the inner region of the core material 1 are integrated via the slit 1A. Only the solidified injection material inside is never pulled out to the ground side.

1 and 3 to 11, the core material 1 is shown in a simple cylindrical shape for simplification of illustration. However, in more detail, the core material 1 has a structure shown in FIG. 2, for example.
In FIG. 2, the core material 1 has a plurality of types (two types in FIG. 2) of cylindrical shapes 1-1 (a cylindrical shape having a smaller diameter) and 1-2 (a cylindrical shape having a larger diameter). ) Are alternately connected. Since the radially outer side (outer peripheral side) region of the cylindrical shape 1-2 having a large radial dimension protrudes radially outward, the periphery of the core material 1 (between the cylindrical shape 1-2 having a large radial dimension) After filling and solidifying a space sandwiched between and a space in the radial direction of the cylindrical shape 1-1 having a small diameter dimension) with an injection material (not shown), the radial direction outward of the cylindrical shape 1-2 The side region (outer peripheral region) becomes a resistance and prevents the core material 1 from being pulled out. This also contributes to the improvement of the peripheral frictional resistance of the lock bolt 10.

  In addition, according to the core material 1 in which the cylindrical shape 1-1 having a small diameter and the cylindrical shape 1-2 having a large diameter are alternately connected, the outer peripheral edge of the cylindrical shape 1-2 having a large diameter Projecting radially outward in the axial direction, the outer peripheral edge of the cylindrical shape 1-2 is intermittent even if the injection material (for example, grout material) tries to escape along the outer peripheral surface of the core material. Since it becomes the resistance of the injection material which is going to escape, it is prevented that the injection material escapes to the ground side.

The core material 1 has a hollow shape as a whole (not shown), and a plurality of through-holes 1 </ b> A (slits) communicating the hollow portion of the core material 1 with the outer surface of the core material 1 are provided in the axial direction of the core material 1. It is formed over. In the example of FIG. 2, the plurality of slits 1 </ b> A are formed at axial positions straddling the cylindrical shape 1-1 having a small diameter and the cylindrical shape 1-2 having a large diameter.
When injecting the injection material, the injection material is supplied to the core material 1 from an injection material supply source (not shown) disposed at the ground side end of the core material 1 via a core material injection attachment (not shown). The supplied injection material flows through the hollow portion of the core material 1 and is injected (discharged) from the plurality of slits 1A toward the ground.

Next, with reference to FIGS. 3-7, the construction procedure of the reinforcement construction method of 1st Embodiment is demonstrated.
In 1st Embodiment, the injection material C is inject | poured into the ground of a rock bolt side surface from several slit 1A (FIG. 6, FIG. 7).
In FIG. 3, for example, a bore hole H having a predetermined depth is drilled on a slope to be constructed by, for example, so-called “casing drilling”. Casing drilling is performed while adding the casing 3 as necessary, but only one casing 3 is shown in FIG. 3 for simplicity of illustration. In FIG. 3, the boring hole H can be drilled by a method other than casing drilling.
In addition, in FIG. 3 to FIG. 7 and FIG. 8 to FIG. 11, for the sake of simplification, the slope that is the object of the reinforcement construction method is shown horizontally.

If the boring hole H is drilled to the predetermined depth of the slope in the process shown in FIG. 3, the core material 1 is inserted into the boring hole H in FIG. At that time, the casing 3 remains in the borehole H in order to prevent the borehole H from collapsing.
The core material 1 is inserted to the vicinity of the underground side end of the inner space of the casing 3 (that is, to the vicinity of the underground side end of the boring hole H). As described with reference to FIG. 2, the core material 1 has a hollow portion (not shown) that serves as a flow path for the injection material C, and a plurality of the hollow portions and the core material outer surface communicate with each other. A slit 1A (through hole) is formed.

If the core material 1 is inserted into the inner space of the casing 3 in the boring hole H (FIG. 4), in FIG. 5, the core material 1 (hollow part) is injected from an unillustrated supply source on the ground side with an injection material C (for example, Grout material) is injected (supplied) (arrow A1: primary injection). In addition, the code | symbol 5 in FIG. 5 has shown the core material injection | pouring attachment for inject | pouring the injection material C into the core material 1 (hollow part).
If the injection material C is injected into the core material 1 (when primary injection is performed), the injection material C passes through a plurality of slits 1A from the hollow portion of the core material 1 to the inner space of the casing 3 (that is, inside the casing 3). Into the annular space between the side surface and the outer surface of the core material 1, and the inner space of the core material 1 (the hollow portion thereof) and the casing 3 is filled with the injection material C.
FIG. 5 shows a state in which the injection material C is filled in the core material 1 (the hollow portion thereof) and the inner space of the casing 3 (after the primary injection). And the process shown in FIG. 6 is performed.

In the process shown in FIG. 6, in a state where the hollow portion of the core material 1 and the inner space of the casing 3 are filled with the injection material C (the state shown in FIG. 5), the casing 3 is moved to the predetermined position P in the axial direction of the boring hole H. Pull it out to the ground side. Then, the injection material C is injected under pressure into the core material 1 (hollow part thereof) (arrow A2: secondary injection).
In FIG. 6, when the injection material C is injected under pressure (secondary injection is performed), the pressure under which the injection material C is injected under pressure is the injection material C in the inner space of the core material 1 (hollow part thereof) and the casing 3. Also works. And the injection material C pressure-injected by secondary injection is applied through the wall surface of the boring hole H from the through-hole 1A of the core material 1 in the ground side rather than the lower end position P of the pulled-out casing 3. Pressurized injection (discharge) into the power ground (arrow B2).

On the other hand, even if the injection material C is injected under pressure (secondary injection is performed), in the region on the ground side from the lower end position P of the drawn-out casing 3, the outside of the through hole 1A of the core material 1 in the radial direction is outside. One side is shielded by the casing 3. Therefore, the injection material C injected (discharged) from the through-hole 1A in the region on the ground side from the lower end position P of the casing 3 is not injected into the ground. That is, in the process of FIG. 6, the injection material C is pressurized and injected (discharged) into the ground only from the through-holes 1 </ b> A (a part of the through-holes 1 </ b> A) from the lower end position P of the casing 3. The injection material C injected (discharged) from the through-hole 1A in the region on the ground side from the lower end position P of 3 is not directly injected into the ground.
Although not clearly shown in FIG. 6, the ground-side end portion of the casing 3 is sealed with a seal member (not shown), so that the injection material C is prevented from flowing out from the ground-side end portion of the casing 3.

Although not shown, according to the inventors' experiment, the injection material C is injected from the through-hole 1A having a small cross-sectional area as compared with the case where the injection material C is injected from the through-hole having a large cross-sectional area. It has been found that the injection pressure easily acts in the ground, and the injection material C is easily injected into the ground.
And it is possible to control the range (injection range) where the injection material C is injected into the ground by changing the cross-sectional area (size) of the through-hole 1A.
That is, in the step of FIG. 6 (secondary injection), the injection material C is injected into the ground by appropriately setting the size (cross-sectional area) of the through-hole 1A (for example, slit) formed in the core material 1. The controlled range (injection range) is controlled.

In the process of FIG. 7 following the process of FIG. 6, the casing 3 is completely pulled out from the boring hole H, and the mouth packer 4 (mouth sealing material) is disposed on the ground side end portion (so-called mouth) of the boring hole H and sealed. ing. Since the mouth seal material 4 is disposed at the ground side end of the borehole H, the injected material C is prevented from flowing out to the ground side (from the ground side end of the borehole H). C is reliably injected into the ground.
Further, the injection material C is injected under pressure (secondary injection: arrow A3).

In FIG. 7, when the injection material C is pressure-injected, the pressure of the pressure injection also acts on the core material 1 (hollow part) and the injection material C in the inner space of the borehole H, and the injection material C is the core material 1. From all the through-holes 1A, pressure is injected (discharged) into the ground through the wall surface of the boring hole H (arrow B3).
After the pressure injection to the ground of the injection material C is completed in the process of FIG. 7 (after the secondary injection is completed), the lock injection 10 shown in FIG. 1 is formed by removing the core material injection attachment 5. The
When the formation of the lock bolt 10 is completed, the ground side end portion of the core material 1 is tightened with a lock nut (not shown), and a tensile force in the ground side direction is applied to the core material 1 to complete the reinforcement method.

In the step of FIG. 5 (primary injection), an injection material (for example, plastic grout) having a higher viscosity than the injection material used in the secondary injection can be injected into the core material 1 (hollow portion thereof) (FIG. 5). Arrow A1). Since the injection material (for example, plastic grout) having a higher viscosity than the injection material C used in the secondary injection has a higher viscosity, it is used in the secondary injection after filling the bore hole H (or in the casing 3). Compared with the case where the same injection material is used, it stays in the borehole H for a long time. And the secondary injection | pouring which inject | pours the injection material C in the ground can be performed without waiting until a plastic grout hardens | cures. Therefore, the construction period can be shortened. In addition, when the injection material (for example, plastic grout) having a higher viscosity than the injection material used for the secondary injection is filled by the primary injection, the high-viscosity injection material (for example, plastic grout) is placed in the bore hole H. There is an advantage that the injection range can be controlled by, for example, performing a limited injection in the secondary injection (pressurization injection) for a long time.
If an injection material (for example, plastic grout) having a higher viscosity than the injection material used for the secondary injection is injected into the core material 1 in the primary injection, a plurality of the injection materials (for example, plastic grout) are introduced from the hollow portion of the core material 1. Through the slit 1 </ b> A into the inner space of the casing 3 (that is, the annular space between the inner surface of the casing 3 and the outer surface of the core material 1), and the core material 1 (hollow part thereof) and the casing 3 The inner space is filled with an injection material (for example, plastic grout) having a higher viscosity than the injection material used in the secondary injection.

  If the boring hole H is filled with a high-viscosity injection material (for example, plastic grout) by the primary injection, the process shown in FIG. 6 is performed. In FIG. 6, when the casing 3 is pulled up to the ground side to the predetermined position P in the axial direction of the borehole H and the injection material C is injected under pressure (arrow A <b> 2 in FIG. 6), the injection material C is pulled out of the casing 3. Is injected (discharged) into the ground to be constructed from the through-hole 1A of the core material 1 on the ground side of the lower end position P of the material through the wall surface of the borehole H (secondary injection: FIG. 6). Arrow B2).

In the primary injection, when an injection material (for example, plastic grout) having a higher viscosity than the injection material used in the secondary injection is filled and injected into the borehole H (for example, in the primary injection step of FIG. Also in the case of injection), in the secondary injection step of FIG. 7, the casing 3 is completely withdrawn from the boring hole H, and the injection material C is injected under pressure (arrow A3 in FIG. 7).
The injection material C is pressure-injected (discharged) from all the through-holes 1A through the wall surface of the boring hole H into the ground to be constructed (arrow B3 in FIG. 7).

Next, a second embodiment of the present invention will be described with reference to FIGS.
In 1st Embodiment mentioned above with reference to FIGS. 3-7, from all the slits 1A (FIG. 6) in the area | region below the lower end part P of the casing C (FIG. 6), or all the underground The injection material C is injected from the slit 1A (FIG. 7). On the other hand, in the second embodiment of FIGS. 8 to 11, the injection material C is injected into the ground not from a large number of slits but only from a small number of predetermined slits (slits sandwiched between packers of the packer tube). .
Also in the second embodiment, the steps shown in FIGS. 3 to 5 are the same as those in the first embodiment, and redundant description is omitted. Moreover, the core material and casing in 2nd Embodiment have the structure similar to the core material 1 and casing 3 of 1st Embodiment, and each has shown with the same code | symbol.

The steps of FIGS. 3 to 5 are common to the second embodiment and the first embodiment. In the step (primary injection) of FIG. 5, after filling the core material 1 (hollow part thereof) and the inner space of the casing 3 (from the underground side end to the vicinity of the ground side end part) with the injection material C, the casing 3 Is removed from the bore hole H. After the casing 3 is pulled out from the boring hole H, the mouth packer 4 (mouth sealing material) is disposed at the ground side end of the boring hole H and is in a sealed state.
In the step of FIG. 8, the injection material discharge pipe 2 (packer pipe) is inserted into the core material 1 (hollow space) (arrow Q). As shown in FIG. 8, the packer tube 2 has a plurality of injection material discharge ports 2B formed in a circumferential direction between the pair of packers 2A and the pair of packers 2A.
After inserting the packer tube 2, the process shown in FIG. 9 is performed.

9, the injection material discharge port 2B (not shown in FIG. 9, see FIG. 8) of the packer tube 2 is positioned so as to align with a predetermined through-hole 1AA (for example, a slit) in the core material 1. The predetermined slit 1AA in the core material 1 is present at a position corresponding to a region where the injection material C should be injected and the ground should be reinforced in the plurality of slits 1A. Also in the second embodiment, the through-opening 1AA can be configured with not only a slit but also a circular or oval hole, or a hole with another shape, and is not limited to a slit.
In addition, when the area | region which should be ground-reinforced is large (about a perpendicular direction), the space | interval between a pair of packers 2A is enlarged, and several predetermined slits 1AA of the axial direction of the core material 1 are located between the said packers 2A. You may do it. Alternatively, although not shown, a plurality of pairs of packers 2A can be provided and a plurality of injection material discharge ports 2B can be formed.
In the state shown in FIG. 9, the pair of packers 2A of the packer tube 2 sandwich the predetermined slit 1AA of the core material 1 so that the injection material discharge port 2B is positioned (aligned) with the predetermined slit 1AA (through port). In addition, a packer tube is arranged. That is, in the state shown in FIG. 9, the injection material discharge port 2B of the packer tube 2 exists at a position corresponding to the predetermined slit 1AA.
If the injection material discharge port 2B is opposed to the slit 1AA as shown in FIG. 9, the process shown in FIG. 10 is executed.

In the step shown in FIG. 10, the pair of packers 2A of the packer tube 2 is expanded by a compressed fluid supply means (not shown). The pair of expanded packers 2A are in pressure contact with the inner wall of the core material 1 to form a space (predetermined space) surrounded by the pair of packers 2A, the outer peripheral surface of the packer tube 2, and the inner peripheral surface of the core material 1. The (predetermined space) communicates with the outside of the core material 1 only by the predetermined slit 1AA.
A path (flow path) through which the injected material C discharged from the injected material discharge port 2B flows into the slit 1A other than the predetermined slit 1AA of the core material 1 is closed by the pair of expanded packers 2A.
Therefore, when the injection material C is pressure-injected (secondary injection) into the packer tube 2 from the injection material supply source on the ground side (step of FIG. 11), the injection material subjected to pressure injection (secondary injection). C is surrounded by the predetermined space (a pair of packers 2A, an outer peripheral surface of the packer tube 2 and an inner peripheral surface of the core material 1) from an injection material discharge port 2B (see FIG. 8) formed between the pair of packers 2A. Into the space) and injected (discharged) into the ground only through a predetermined slit 1AA.

In the process of FIG. 11, the injection material C is pressure-injected into the packer tube 2 from the injection material supply source through the core material injection attachment 6 (arrow A4). As described above, the injection material C (for example, grout material) injected under pressure flows through the packer tube 2 toward the underground side, and an injection material discharge port 2B formed between the pair of packers 2A (FIG. 11 is a diagram). It is injected only into the predetermined space (a space surrounded by the pair of packers 2A, the outer peripheral surface of the packer tube 2, and the inner peripheral surface of the core material 1) from only the case (see FIG. 8). Then, pressure is injected (discharged) into the ground through the predetermined slit 1AA of the core material 1 and the wall surface of the boring hole H (arrow B4).
As described above with reference to the process of FIG. 6 in the first embodiment, according to the inventor's experiment, when the injection material C is secondarily injected from the through hole 1A having a small cross-sectional area, the injection material C is injected from the through hole having a large cross-sectional area. Compared to the case of secondary injection, it has been confirmed that the injection pressure is likely to act in the ground and the injection material C is likely to be injected into the ground, and the cross-sectional area (size) of the through-hole 1A is changed. By doing, the range (injection range) by which the injection material C is injected into the ground can be controlled.
Therefore, also in the process of FIG. 11, by appropriately setting the size (cross-sectional area) of the through-hole 11A (for example, a slit) formed in the core material 1, the range in which the injection material C is injected into the ground (injection) Range) can be controlled.

After the pressure injection (secondary injection) of the injection material C to the ground is completed in the step of FIG. 11, if the core material injection attachment 6 is removed, the formation of the lock bolt is completed.
When the formation of the lock bolt is completed, as in the first embodiment, the ground side end of the core material 1 is tightened with a lock nut (not shown), and a tensile force in the ground side direction is applied to the core material 1 to perform the reinforcement method. Complete.

Here, also in the second embodiment, secondary injection is performed from the ground-side supply source to the core material 1 (hollow portion) in the step shown in FIG. 5 (primary injection step) immediately before the step of FIG. An injection material (for example, plastic grout) having a viscosity higher than that of the injection material used in the above can be injected (arrow A1 in FIG. 5).
As described above, by using an injection material (for example, plastic grout) having a viscosity higher than that of the injection material used in the secondary injection, the high-viscosity injection material (for example, plastic grout) is placed in the borehole H (casing 3). After the primary injection into the inner), the injection range in the secondary injection can be controlled by performing a limited injection or the like.
Other configurations and operational effects in the second embodiment are the same as those in the first embodiment.

It should be noted that the illustrated embodiment is merely an example, and is not a description to limit the technical scope of the present invention.
For example, in the first embodiment, when the casing 3 is moved in the axial direction of the bore hole H, the casing 3 is pulled out in two stages, the state shown in FIG. 6 and the state shown in FIG. Pressure injection. However, the casing 3 can be finely moved in the axial direction of the boring hole H, pulled out so as to be in three or more stages, and the injection material C can be poured.
Further, the process shown in FIG. 6 is omitted, and immediately after the boring hole H is cut, the casing 3 is completely extracted from the boring hole H (withdrawal in one step), and the injection material C is all slits of the core material 1. It is also possible to perform pressure injection from 1A into the ground in only one step.
In the second embodiment, two or more pairs of packers 2A are arranged in the packer tube 2, and the injection material C is injected from a plurality of injection material discharge ports 2B separated in the axial direction of the boring hole H. You can also.
In addition to this, in the illustrated embodiment, a slit is shown as the through-hole 1A. However, the through-hole 1A can be formed of a circular or oval hole or other shape.

1 ... Core 1A ... Slit (through hole)
1AA ... predetermined through-hole (through-hole through which injection material should be injected)
1-1, 1-2... Rotating body (for example, cylindrical)
2 ... Packer tube (injection material discharge tube)
2A: Packer 2B ... Injection material discharge port 3 ... Casing 4 ... Mouth packer (mouth sealing material)
C ... Injection material (eg grout material)
H ... Boring hole

Claims (5)

A step of drilling a boring hole;
Inserting a hollow core material having a through-hole into the borehole;
A reinforcing method comprising a step of supplying an injection material into a hollow portion of a core material and injecting the injection material into the ground from the through hole. A plurality of the through holes are formed,
The reinforcing method according to claim 1, wherein in the step of injecting into the ground, the injection material is injected from all through holes. A plurality of the through holes are formed,
The step of injecting into the ground includes inserting an injection material discharge pipe having a packer and an injection material discharge port into the core material, positioning the injection material discharge port of the injection material discharge pipe at a predetermined through-hole of the core material, The reinforcing method according to claim 1, wherein the packing material is expanded and the injection material is injected only from the through-hole positioned with the injection material discharge port of the injection material discharge pipe.   The reinforcing method according to one of claims 1 to 3, comprising a step of supplying a highly viscous injection material into the hollow portion of the core material and filling the casing from the through hole.   The reinforcing method according to any one of claims 1 to 4, wherein the core material has a shape in which a plurality of types of rotating bodies having different diameters are alternately connected.

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