JPS6389800A - Method of lock bolt fixing construction in method of natm construction of tunnel - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field] In the NATM tunnel construction method, a rock bolt can be easily and efficiently fixed in a borehole with mortar in the NATM construction method. This relates to the rock bolt fixing method.

[Conventional technology]

In the NATM method of tunnel construction, the construction procedure is that after tunnel excavation, boreholes 1 (rock bolt holes) are drilled on the entire circumferential wall of the tunnel as shown in Figure 1, and rock bolts 2 are fixed in these boreholes 1. After injecting and filling mortar 3 for this purpose, a lock bolt 2 with a washer 4 and a nut 5 attached is driven in and fixed through the mortar 3.

Thereafter, this surface will be lined by spraying mortar, etc. to form a tunnel.

When injecting mortar 3 into this borehole 1, considering the construction speed, several boreholes 1 are injected and filled at once almost up to the entrance, and then rock bolts 2 are driven in. The following three problems can be raised.

1. After the mortar 3 is injected into the borehole 1 and before the lock bolt 2 is driven in, the mortar 3 may flow out from the upward facing borehole 1.

2 When driving the rock bolt 2, it is desirable that an amount of mortar 3 approximately corresponding to the volume of the driven rock bolt 2 flows out from the borehole 1, but in the upward facing borehole 1, an excess of mortar 3 flows out from the borehole 1. may flow out, making the lock bolt 2 incompletely fixed.

3. The volume of the rock bolt 2 is approximately 30% of the amount of mortar 3 injected into the borehole 1, which is equivalent to the amount of mortar that flows out from the borehole 1 when driving the rock bolt 2, and is wasted. The tunnel floor becomes dirty with spilled and fallen mortar, which makes work difficult as cleaning up is required.

In response to the above problem l, at present, as shown in Fig. 3, when pouring mortar 3 into the borehole 1, a mortar outflow prevention member 6 like a tortoise scrubbing brush is inserted near the entrance of the borehole 1. This prevents the mortar from flowing out after pouring the mortar 3, but after the rock bolts 2 are driven, this mortar spill prevention member 6 is often removed (at the client's request) because it becomes a foreign substance to the concrete. This removal also poses problems, especially in the ceiling of the tunnel and the walls near it, which require time and effort, such as using hydraulic lifters to go up and down from the work floor, and are difficult to install. be.

Regarding problem 2 above, at present, as shown in Figs. 4 and 5, a movable rubber plate 7 or a styrofoam lump 8 (water pipe heat insulation member) is attached to the lock bolt 2 to control the population of the borehole 1 when driving the lock bolt 2. Measures are being taken to block it.

However, in this method, near the end of driving the lock bolt 2, the movable rubber plate 7 or the Styrofoam block 8
It is necessary to remove the nut, drive in the additional thickness, and tighten the nut 5, which not only complicates the work, but also causes problems such as the workability is extremely poor in ceiling areas and high places where there is a lot of climbing up and down from the work floor. .

None of the above methods for preventing mortar outflow take into account Problem 3, and cannot be said to be a method for solving the problem when considering actual workability.

[Problem that the invention seeks to solve]

The present invention has solved this problem, and the technical problem is to provide a rock bolt fixing method in the NATM tunnel construction method that has excellent workability and can fix rock bolts with only a small amount of mortar flowing out. It is.

[Means for solving problems]

The mortar injection pipe 11 is inserted into the borehole 10 that is radially bored in the entire peripheral wall of the tunnel by a conventional method until it reaches near the bottom of the borehole 10, and the mortar injection pipe 11 is inserted at a speed commensurate with the amount of mortar injection. After injecting and filling a predetermined amount of mortar while retracting the mortar 11, a rock bolt is driven into the borehole 10 filled with mortar, and the rock bolt is inserted into the borehole 10 through the mortar. Rock bolt fixing method I in the NATM construction method for tunnels fixed to
Here, when inserting the mortar injection pipe 11 into the borehole 10, an annular mortar stopper 16 made of a material that can be embedded in the inner hole of the borehole 10 in concrete is movable around the outer periphery of the mortar injection pipe 11. This mortar injection pipe 11 is inserted into the borehole 10, and mortar is injected and filled with the mortar stopper 16 blocking the borehole 1 (l) near the inlet. After pulling out the mortar injection pipe 11 to the outside, a lock bolt 5 is driven into the guide hole 17 at the center of the mortar stopper 16, and the lock bolt 15 with the mortar stopper 16 is fixed in the borehole 10 via a mortar lock.

〔Example〕

The mortar stopper 16 shown in FIG. 8 is made by pressing a thin iron plate, and has a guide hole 17 in the center through which the lock bolt b and the mortar injection pipe 11 pass, and a short elastic locking plate 19 on the outer periphery of the ring plate and a long one. The figure shows a case in which elastic locking plates 20 are alternately provided radially protruding downward, and mortar outflow prevention protrusions 4 are provided radially upwardly protruding at several locations on the inner edge of the guide hole 17.

The mortar stopper 16 shown in FIG. 9 has an elastic locking plate 19 of the same length radially protruding downward from the lower peripheral edge of a guide cylinder 22 with grooves 21 also made of a thin iron plate. .

The mortar stopper 16 shown in FIG. 10 also has short elastic locking plates 19 and long elastic locking plates 20 radially projected downward alternately on the lower peripheral edge of the guide cylinder n with grooves 21 made of a thin iron plate. Although the mortar stopper 16 is shown in the drawing, other structures may be used as long as the mortar stopper 16 has a structure that elastically locks the inner hole of the borehole 10 at the outer periphery and prevents the injected mortar cap from flowing out.

The mortar stopper 16 should preferably be locked at a position tenth from the population of the borehole 10.

In the figure, 13 is a washer and 14 is a nut.

〔Effect of the invention〕

With the above construction, the present invention not only prevents the mortar from flowing out after pouring mortar into the borehole 10, but also allows the amount of mortar commensurate with the amount of rock port 15 to be driven from the gap between the mortar stopper 16 when driving the rock bolt 15. He moved in the direction of the borehole 10 into the gap between the borepole 10 and the rock bolt 15 to prevent the mortar from flowing out abnormally, and to generate appropriate pressure in the borehole 10 to tighten the rockbolt 15. Fixation can be made even more complete.

Furthermore, as mentioned above, since the movement of mortar within the borehole 10 is very stable, it is possible to significantly reduce the amount of mortar used, and the construction can be carried out almost in the same way as when the mortar stopper 16 is not used. It can be done without the complicated labor required in the conventional method.

Moreover, the mortar stopper 16 embedded in the borehole 10 can hold the lock bolt at the center of the borehole 10, so the lock bolt 15 can be fixed at the center of the borehole 10, and this mortar stopper 16 The tunnel NA has excellent features such as being made of a material that can be embedded in concrete, such as metal, so it blends in with concrete and can be permanently embedded in the borehole 10 like the rock bolt 15.
This will provide a rock bolt fixing method in the TM construction method.

[Brief explanation of the drawing]

Figure 1 is a front cross-sectional view showing a part of the tunnel using the NATM construction method.
Figure 2 is a front sectional view showing the steps of the NATM tunnel construction method, Figure 3.4.5 is a front sectional view showing the conventional mortar outflow prevention method, and Figure 6 is a front sectional view showing the steps of the method of the present invention. 7 are front sectional views of essential parts of the method of the present invention, and FIGS. 8, 9, and 10 are oblique views of the mortar stopper. 10...Borehole, 11...Mortar injection pipe, Minoru...Mortar, 15...Rock bolt, 16...Mortar stopper, 17...Center bolt hole, U...Tunnel all around wall. difference? Nearing 7y mark 7=+a 7 ke direction pu 2艷nnosaio/:A

Claims (1)

[Claims] Insert the mortar injection pipe into a borehole that has been radially drilled on the entire peripheral wall of the tunnel by a conventional method until it reaches near the bottom of the borehole, start pouring mortar, and then retreat the mortar injection pipe at a speed commensurate with the amount of mortar injected. In the rock bolt fixing method in the NATM tunnel construction method, in which a predetermined amount of mortar is injected and filled, a rock bolt is driven into the borehole filled with mortar, and the rock bolt is fixed in the borehole via the mortar. When a mortar injection pipe is inserted into a borehole, an annular mortar stopper made of a material that can be embedded in concrete that closes the inner hole of the borehole is movably fitted around the outer periphery of the mortar injection pipe, and the mortar injection pipe is inserted into the borehole. Insert the injection pipe into the borehole, fill the mortar with the mortar stopper blocking the entrance of the borehole, and then pull the mortar injection pipe outside with the mortar stopper left in place. A rock bolt fixing method in the NATM tunnel construction method, which is characterized by driving a rock bolt into a guide hole and fixing this rock bolt with a mortar stopper in the borehole via mortar.