JPS6122091B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rock bolt or earth anchor (hereinafter simply referred to as a bolt) fixed to a ground such as bedrock or earth, and a rock bolt or earth anchor (hereinafter simply referred to as a bolt) that is fixed to an exposed portion of the bolt to prevent deformation or collapse of the ground. and a restraining plate.

Conventionally, as a synthetic anchor of this type, there was one in which a rock bolt was fixed to the excavated wall of a tunnel or the like, and a metal bearing plate was attached to this with a nut to support the ground. However, since it is impossible for the metal plate mentioned above to adhere closely to the excavated wall surface, which has many irregularities, the entire surface of the plate cannot support the ground, and it not only requires measures such as shotcrete or lining concrete. Due to the limited size of the metal plate from the viewpoint of transportation and installation workability, it was not possible to support a wide area of the ground with one plate, that is, one bolt, and as a result, a large number of rock bolts were required to be installed. There were disadvantages such as the need for a long period of time for construction.

The present invention was made in order to eliminate the drawbacks of the conventional synthetic anchors mentioned above.The purpose of the present invention is to enable safe and highly efficient construction, to provide a plate with high rigidity and desired shape and size on-site. To provide a method for constructing a synthetic anchor that can be easily molded and is integrated with the ground.

Embodiments of the present invention will be described below with reference to the drawings.

In Fig. 1, reference numeral 1 denotes a ground consisting of bedrock or earth, to which a bolt 2 is fixed by a known method, and an insertion hole 3a of a flexible formwork is inserted into an exposed portion 2a of the bolt 2. Then, set the flexible formwork 3.

The flexible formwork 3 is made of, for example, synthetic fibers with high tensile strength such as nylon, polyester, polyacrylic, polypropylene, vinylon, polyethylene, etc., chemical fibers such as rayon, Kyupra, acetate, etc., or natural fibers such as cotton, hemp, wool, etc. It is made of woven fabrics, knitted fabrics, non-woven fabrics, etc. made from materials such as materials, and is highly flexible and is formed into the desired shape and size of the plate, forming a space for filling with fluids such as fluid concrete or mortar. It is bag-shaped and has an injection port 3b on one side.

Next, as shown in FIG. 2, a frame 4 is installed from the outside of the flexible formwork 3, and is attached to the exposed part 2a of the bolt 2 with a nut 6 through a washer 5, and between it and the ground 1. Supports the flexible formwork 3.

As shown in FIG. 4A, the frame 4 is constructed by appropriately bending and welding materials such as reinforcing bars or iron pipes into a truncated pyramidal cage shape. The frame 4 may also be constructed in the shape of a frustoconical cage as shown in FIG. 4B, or may be constructed by assembling thin reinforcing bars in a lattice shape as shown in FIG. 4C. As described later, it may have any shape and size as long as it can support the flexible form 3 expanded by press-fitting a fluid such as fluid concrete or mortar. Although the washer 5 is integrally welded to the center of each frame 4 in the above embodiments, separate washers may be assembled during construction.

When the installation of the flexible formwork 3 and frame 4 is completed as described above, as shown in FIG. The fluid concrete 9 is injected into the flexible formwork 3 from the pressure feeding device 7. As the flexible formwork 3 is filled with concrete, the air inside the flexible formwork 3 is exhausted through the material, and the flexible formwork 3 is evacuated due to the strength of the material and within the constraints of the frame 4. It gradually expands and reaches frame 4.
It receives the reaction force of the bolt 2 through the bolt 2 and comes into close contact with the surface of the ground 1. Furthermore, when the filling pressure of concrete 9 increases within the flexible formwork 3, concrete mixing water oozes out from the seams of the flexible formwork 3, and when the predetermined injection pressure is finally reached, the injection port 3b
At the same time, the injection port 3b is closed by activating a suitable automatic shut-off valve (not shown) provided in the inlet 3b (not shown), or by tying the inlet 3b with a string or the like, and at the same time, the pressure feeding is stopped and the transport pipe 8 is disconnected.
When the kneading water is squeezed out from the flexible formwork 3 as described above, the water-cement ratio decreases, hardening is accelerated, and a high-density, high-strength concrete plate is self-formed.

In the above embodiment, the material of the flexible formwork 3 is made water permeable so that the kneading water comes out, but it is not necessarily necessary to make it water permeable. It does not need to be made of breathable material as long as air vent holes are formed. Further, in the above embodiment, the insertion hole 3a is formed in the center of the flexible formwork 3, and the exposed portion 2a of the bolt 2 is inserted through the insertion hole 3a.
It is also possible to omit this step and directly punch through the material of the flexible formwork 3 to make a hole and pass the bolt 2 through.
In this case, in order to prevent the pumped concrete 9 from ejecting from the gap between the hole and the bolt 2, a separate washer may be tightly attached just outside the gap. In addition, if the surface of the ground 1 is particularly uneven, the material of the flexible formwork 3 in contact with the ground 1 may be made of a material that will break when the concrete reaches a predetermined high pressure, or it may be made of a material that can be expanded and contracted. It is also possible to further improve adhesion by using fibers or woven fabrics that have elasticity and digging into the recesses of the ground. When a stretchable fabric is used as described above, the pressure of the filled concrete spreads its fibers, allowing the concrete to leak through the gaps and come into direct contact with the ground surface, making it even more integrated with the ground. It has an easy-to-understand effect. In addition, in the above embodiment, the flexible formwork 3 was configured in a bag shape, but
For example, it may be of the shape of a tube, as long as it has a space that can be filled with a fluid.

Further, in the above embodiment, the flexible formwork 3 is first set on the bolt 2, and then the frame 4 is attached from the outside, but the method of the present invention is not limited to this, and the flexible formwork 3 is attached to the frame 4 in advance. 3 may be assembled in advance and attached to bolt 2 at the same time.

In addition, reinforcing reinforcing bars 10 and spiral bars 11 are arranged within the flexible formwork 3 to reinforce the plate, as shown in FIG. 5, or reinforcing materials such as fibers are mixed into the concrete. It's okay to stay. Furthermore, in the above embodiment, the flexible formwork 3 is supported from the outside by the frame 4, but as shown in FIG. The pipes 13 are joined by welding or the like, and their outer ends 12b are connected to the flexible formwork 3.
The material on the ground side may be pressed against the ground surface. In this case, the frame 12 has the advantage of also serving as the reinforcing reinforcing bar 10. In this embodiment, threads 14 made of nylon, polyester, etc. are stretched inside the flexible formwork 3 to restrain the flexible formwork 3 to maintain a desired flat shape, and also to serve as a concrete reinforcing material. There is.

Although FIG. 7 shows a state in which a plurality of synthetic anchors are formed in the ground by the method of the present invention, the synthetic anchors constructed by the method of the present invention are not limited to those mentioned above, and for example, as shown in FIG. Alternatively, several bolts may form one continuous plate.

As described above, the method for constructing a synthetic anchor according to the present invention can be used for forming bearing plates of rock bolts in the NATM construction method, stabilizing slope construction methods, retaining walls such as retaining walls, and shoring of underground cavity structures. It is something that can be used.

Next, the effects of the present invention will be listed.

(b) Since the flexible, lightweight formwork is set on bolts fixed in the ground, it is extremely easy to transport to the construction site and set on the bolts, allowing for safe and highly efficient construction.

(b) Since the frame is attached to the bolts to support the flexible formwork, the frame can not only be constructed easily and lightweight, but also the reaction force of the bolts caused by the expansion of the flexible formwork can be easily removed. By bringing the formwork into close contact with the ground surface, it is possible to form a synthetic anchor that is integrated with the ground.

(c) Since the plate is formed by pouring concrete, mortar, etc. into the flexible formwork set on the bolts and hardening it, the pouring work can be done easily and quickly, and the plate can be formed with high rigidity. .

(d) Since we used a flexible formwork that is highly flexible and has a space for filling with fluids such as concrete, the materials and construction costs for the formwork are low, and plates of any shape and size can be formed. can be easily formed on site.

[Brief explanation of the drawing]

Figures 1 to 3 sequentially explain one embodiment of the method for constructing a synthetic anchor of the present invention. Figure 1 is a cross-sectional view of the flexible formwork set on the lock bolt, and Figure 2 is a cross-sectional view of the state in which the frame is attached. Fig. 3 is a cross-sectional view of the state in which concrete is press-fitted into the flexible formwork and hardened. Fourth
Plane a of various frame embodiments in figures A to 4C
FIG. 5 is a sectional view showing another embodiment in which reinforcing bars etc. are arranged within the flexible formwork, and FIG. 6 is still another embodiment in which the frame is arranged within the flexible formwork. 7 and 8
Each figure is a sectional view showing an example of construction on the ground. 1... Earth, 2... Bolt, 2a... Exposed part,
3... Flexible formwork, 3a... Insertion hole, 3b
...Inlet, 4...Frame, 5...Washer, 6...
... Nut, 7 ... Pressure feeding device, 8 ... Transport pipe, 9 ...
...Fluid concrete, 10...Reinforcement reinforcing bars, 11
...Spiral muscle, 12...Frame, 13...
Insertion tube, 14... thread.

Claims (1)

[Claims] 1. Fix bolts such as rock bolts or earth anchors to the ground; attach a flexible formwork with a space for filling fluids such as concrete or mortar in the exposed part of the bolt, and a frame to support the flexible formwork. Attachment: A method for constructing a synthetic anchor, comprising injecting the fluid into the space of the flexible formwork and curing it to form a plate integrated with the ground and bolts.