JP2000008388A - Natural ground reinforcing construction method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To firmly anchor an anchor member to the stable natural ground and to prevent the rupture of the anchor member in the unstable natural ground part by mounting pressure-fitted grips to the specific places of a prestressing strand of the anchor member. SOLUTION: An anchor member 10 is inserted in a hole 11 drilled in the natural ground, grout material 12 is filled, and the anchor member 10 is prestressed and anchored near the surface of the natural ground by anchor means. This anchor member 10 is constituted by mounting pressure fitted grips 14 to a prestressing strand 13, and the mounted positions are the positions of the stable natural ground G2, G3 in front and in the rear of the unstable natural ground G1. The pressure-fitted grips 14 are previously mounted in a factory or can be mounted at a construction site. The anchor member 10 is therefore anchored firmly to the stable natural ground G2, G3 to prevent the generation of an adhesion failure, and adhesive strength is lowered in the natural ground G1 by the adhesion of only the prestressing strand 13 to prevent stress concentration, which results in preventing the rupture of the anchor member 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ground reinforcement method suitable for reinforcing ground such as tunnels, underground cavities, slopes and slopes.

[0002]

2. Description of the Related Art Conventionally, anchor members such as rock bolts and cable bolts of a whole grout type have been used for reinforcing and supporting grounds such as tunnels, underground cavities, slopes and slopes. A deformed steel bar is mainly used as a lock bolt, and a PC steel stranded wire is mainly used as a cable bolt.

[0003]

However, the conventional ground reinforcement method as described above has the following problems. As shown in FIG. 3A, when the lock bolt 1 is used as the anchor member, the lock bolt 1
The wire itself has lower breaking strength than a steel strand, and may lead to breaking.

On the other hand, as shown in FIG. 3B, when a PC steel stranded wire 2 is used as an anchor member, the PC steel stranded wire 2 is used.
The adhesive strength to the grout material 3 filled in the periphery is significantly inferior to that of the rock bolt 1, and the adhesion may be broken at the interface between the PC steel stranded wire 2 and the grout material 3.

In order to solve such a problem, a technique has been developed in which the surface of the PC steel stranded wire 2 is coated or indented to increase the bonding strength with the grout material 3. However, as shown in FIG. 3 (c), the ground and the PC steel strand 2
If a displacement occurs between the PC and PC
There is a case where the adhesion between the steel strand 2 and the grout material 3 does not occur, and the grout material 3 itself is sheared and broken. In addition, the load acting on the PC stranded wire 2 is different between the slip surface or discontinuous surface portion of the ground and the other stable portion. The line 2 itself may be broken.

The present invention has been made in consideration of the above points, and has as its object to provide a ground reinforcement method that can stabilize the ground more effectively.

[0007]

The invention according to claim 1 is
An anchor member extending in one direction is cast in the ground in order to reinforce the ground, and the anchor member has, before and after a portion to be reinforced such as a slip surface or a discontinuous surface of the ground, It is characterized in that a fixing device for increasing the fixing power to the ground other than the portion to be reinforced is mounted. The invention according to claim 2 is characterized in that the anchor member is a PC steel strand. Further, the invention according to claim 3 is characterized in that the fixing tool is a pressure grip.

[0008] In this manner, anchoring devices such as crimping grips are attached to anchor members such as PC steel strands cast in the ground before and after a portion to be reinforced such as a slip surface or a discontinuous surface of the ground. By doing so, the anchor member exhibits adhesion strength only by the anchor member in the portion to be reinforced, and exhibits high adhesion strength in the portion where the fixing device is attached, that is, in the stable portion other than the portion to be reinforced. become.

[0009]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing an embodiment of a ground reinforcement method according to the present invention; FIG.

In FIG. 1, reference numeral 10 denotes an anchor member 10 that is cast on the ground to be reinforced.

As shown in FIG. 1, the anchor member 10
Is inserted into the hole 11 drilled in the ground,
1 is filled with a grout material 12. Prestress is introduced into the anchor member 10, and one end of the anchor member 10 is fixed by a PC fixing tool (not shown) near the surface of the ground.

The anchor member 10 is made of a PC steel strand 1
3 and a crimping grip (fixing device) 14 attached to a predetermined position of the PC steel strand 13.

The crimping grip 14 is provided not at the ground G1 which is a slip surface or a discontinuous surface, but at the portions corresponding to the grounds G2 and G3 before and after the ground G1 which are more stable than the ground G1. , A plurality of which are fixed to the strand 13 of PC steel. Note that “before and after” here means PC
This means forward and backward in the direction in which the steel strands 13 are continuous.

Accordingly, the anchor member 10 is
In the ground, G1 which is a slip surface or a discontinuous surface
The ground G2 before and after the ground G2 and G3 exhibit a high bonding strength, and the ground G1 which is a slip surface or a discontinuous surface has a lower bonding strength.

By the way, when the anchor member 10 is cast, the crimping grip 14 may be attached to the PC steel strand 13 in advance at a factory, or the PC steel strand 13 may be wound around a reel by reeling. And brought in by PC
The crimping grip 14 may be mounted on the site at a predetermined position while the steel stranded wire 13 is inserted into the hole 11. In the latter case, the automatic placement machine for the anchor member 10 may be provided with a function of attaching the crimping grip 14.

Here, FIGS. 2A to 2D show various forms in which the ground is reinforced by the anchor member 10. FIG. As shown in these figures, the anchor member 10
In consideration of the direction of the slip surface or the discontinuous surface Z existing in the ground and the predicted direction of the slip or the collapse of the ground (indicated by the arrow in the figure), the direction of the anchor member 10 and the driving depth , And the mounting position of the crimp grip 14 are set.

In the above-mentioned ground reinforcement method, the anchor member 10 cast in order to reinforce the ground is located before and after the ground G1, which is a portion to be reinforced such as a slip surface or a discontinuous surface. The crimping grip 14 is attached to a portion corresponding to the ground G2, G3. As a result, the anchor member 10 is mainly fixed with high strength at the portion where the crimping grip 14 is mounted, that is, at the stable ground G2 and G3 before and after the ground G1 to be reinforced. . Therefore, the anchor member 10 exerts a high adhesive strength to the surrounding grout material 12 at the portion where the pressure grips 14 are attached, and can prevent the occurrence of adhesive breakage at this portion. On the other hand, in the ground G1 to be reinforced having a slip surface, a discontinuous surface, and the like, since the crimping grip 14 is not mounted, the anchor member 10 uses only the PC steel stranded wire 13 with respect to the surrounding grout material 12. Demonstrates adhesion strength. Therefore, it is possible to suppress the load locally acting on the anchor member 10 at this portion, and as a result, the breakage of the anchor member 10 itself is prevented. As described above, by employing the anchor member 10 having the above-described configuration, the reinforcing effect of the ground can be further enhanced.

Further, a PC steel stranded wire 1 is attached to the anchor member 10.
By using No. 3, the anchor member 10 itself has high breaking strength as compared with the case where a lock bolt is used. Thereby, the high ground reinforcement effect can be exhibited as the whole anchor member 10.

Further, by using the crimping grip 14 as a fixing tool, existing parts can be used.
The above effects can be obtained at low cost.

In the above embodiment, the strand 13 is made of PC steel strands for the anchor member 10. However, it is needless to say that the anchor member 10 may be appropriately reinforced according to the geology of the ground to be reinforced and the required reinforcing effect. Can be used.
Of course, in some cases, it is also possible to use a lock bolt instead of the PC steel strand 13. In addition, when a new material that replaces the PC stranded wire or the lock bolt is developed, it may be appropriately adopted.

The fixing device 14 also includes a fixing grip 14.
Other than these can be used as appropriate. For example, when a lock bolt is used as the anchor member, a nut or the like may be used as a fixing tool. In addition to this, other materials may be used as long as they can be easily mounted and exhibit the required adhesive strength. For example, the anchor member and the fixing device are integrally formed. It is also possible. Of course, the fixing tool may be mounted in a factory or the like in advance, or may be mounted on site.

Further, the object on which the anchor member 10 is to be cast is not limited at all, and may be any ground such as a tunnel, an underground cavity, a slope or a slope. In addition, the anchor member 10 may be a member that is expected to have a permanent ground reinforcing effect permanently, or may be provided as a support for stabilizing the ground only during the construction period.

Other than this, any configuration may be adopted as long as it does not deviate from the gist of the present invention, and it is needless to say that the above-described configurations may be appropriately selectively combined. No.

[0024]

As described above, according to the ground reinforcement method according to claim 1, an anchor member extending in one direction is cast in order to reinforce the ground. A fixing device is provided before and after a portion to be reinforced such as a slip surface or a discontinuous surface of the ground. As a result, the anchor member is fixed with high strength mainly in the stable ground before and after the part to be reinforced, and therefore, the adhesion between the anchor member and the surrounding grout material in this part is reduced. The occurrence is prevented. on the other hand,
In areas where reinforcement is required, such as slip surfaces or discontinuous surfaces, the fixing device is not attached and the adhesion strength is exhibited only by the anchor member, so that the load is not locally applied to the anchor member in this part. As a result, breakage of the anchor member itself is prevented. In this way, it is possible to further enhance the ground reinforcing effect of the anchor member.

According to the ground reinforcement method according to the second aspect, by using a PC steel strand for the anchor member, the anchor member itself has a higher breaking strength as compared with the case where a lock bolt is used. . Thereby, a high ground reinforcement effect can be exhibited as the whole anchor member.

According to the ground reinforcement method according to the third aspect, by using a pressure grip as a fixing tool, existing parts can be used, and the above-mentioned effect can be obtained at low cost.

[Brief description of the drawings]

FIG. 1 is a view showing an example of a ground reinforcement method according to the present invention, and is a cross-sectional view along an axis of an anchor member and a cross-sectional view orthogonal to the axis.

FIG. 2 is a model diagram of a ground reinforced by the anchor member.

FIG. 3 is a view showing a destruction mode of an anchor member in a conventional ground reinforcement method.

[Explanation of symbols]

 10 Anchor member 13 PC steel strand 14 Crimping grip (fixing tool)

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Toru Abe 1-3-2 Shibaura, Minato-ku, Tokyo Shimizu Corporation (72) Inventor Atsushi Nakaya 1-3-2 Shibaura, Minato-ku, Tokyo Shimizu Corporation (72) Inventor Masaki Imazu 1-3-2 Shibaura, Minato-ku, Tokyo Shimizu Corporation Shimizu Corporation (72) Inventor Toru Tanaka 2-34, Nihonbashi-Muromachi, Chuo-ku, Tokyo F term in the company (reference) 2D041 GA01 GB01 GC01 2D044 EA01

Claims (3)

[Claims] An anchor member extending in one direction is cast into the ground to reinforce the ground, and the anchor member should reinforce a slip surface or a discontinuous surface of the ground. A ground reinforcement method, wherein a fixing device for increasing the fixing power to the ground other than the part to be reinforced is attached before and after the part. 2. The method of claim 1, wherein:
The ground reinforcement method, wherein the anchor member is a PC steel strand. 3. The ground reinforcement method according to claim 1, wherein the fixing tool is a pressure grip.