JPS6354116B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tunnel excavation method that improves excavation efficiency by using a combination of blasting and an expandable crushing agent. Conventionally, tunnel excavation work has been carried out by a blasting method using explosives or a mechanical excavation method using a tunnel boring machine. In particular, with mechanical excavation methods, when the rock strength exceeds 600 to 700 kg/cm ² , mechanical wear and tear is severe, making it difficult to use from the economical and excavation speed standpoints. It has been implemented. However, the blasting method causes pollution to the surrounding environment such as vibrations, and it is becoming difficult to carry out construction in areas where safety features such as residential buildings, roads, and railways are nearby.
Various problems have arisen in terms of safety and tunnel durability, such as over-excavation due to blasting vibrations and loosening of surrounding rocks. Among these, the smooth plasting method has been widely adopted as a measure to reduce over-excavation, but although it is effective on hard rocks, it has the disadvantage that it is less effective on soft rocks.

As a result of intensive research into a tunnel excavation method that prevents over-excavation during blasting and reduces vibration, regardless of whether it is soft rock or hard rock, the inventor has found that line drilling is carried out at regular intervals along the outer circumference of the planned tunnel excavation area. The present invention was completed by focusing on the fact that it is sufficient to blast a predetermined portion after applying an expandable crushing agent to the drilled hole.

The contents of the present invention will be explained below with reference to the drawings. 1st
The figure is a front view showing a solid line aspect of the construction method of the present invention.
In the figure, reference numeral 1 indicates a planned area for tunnel excavation in the rock, and line drilling will be performed along its outer periphery 1a at a hole interval of 20 to 50 cm. Hole 2 drilled in this way,
2, 2, ... have a hole diameter of 3 to 8 cm and a hole length of about 1.5 to 5 m. These are filled with an expansive crushing agent such as Plaister (manufactured by Onoda Cement Co., Ltd.), and the pores of the rock are 2.Curing for a period of time until a crack appears between the two. After that, create a gap of about 50 to 100 cm from holes 2, 2, 2, ... towards the center of the tunnel,
Explosive powder such as dynamite is charged at a position closer to the center and blasting is performed.

In addition, in practice of the present invention, the length of the hole is:
The longer the tunnel is, the more likely it is that the tunnel will be drilled outward from the area where the tunnel is to be excavated, so it is not preferable to make it longer than 5 m. Conversely, the shorter the length, the better the dimensional accuracy will be, but it will take a longer curing time to reach the required crushing force after filling with the expandable crushing agent.
Less than 1.5m from the top of tunnel excavation efficiency is not preferable.

Moreover, if the blasting is carried out at a position less than 50 cm from holes 2, 2, 2, etc., there is a possibility that over-excavation will occur.

On the other hand, in the tunnel excavation method, after blasting the central part 1b of the planned excavation part 1 and removing the core,
There is a method of blasting the widened part 1c around b, but in this method as well, line drilling is performed along the outer circumference of the tunnel as described above, and the widened part 1c is blasted.
A small hole 3 may be suitably drilled in the hole 3, filled with an expandable crushing agent, and after curing for a certain period of time, blasting may be carried out in the same manner as described above. In addition, as for the drilling of the widened part 1c, depending on the rock quality, the size of the tunnel diameter, etc., normally, an appropriate number of holes with a hole diameter of 2 to 8 cm and a hole length of 3 to 7 m are bored at intervals of 50 to 70 cm. It's good to do that.

When using an expanding crushing agent after core blasting as described above, the amount of blasting after filling with the expanding crushing agent is 1/2 to 1/5 of the usual amount. In addition, in this construction method, even if the hole length of the hole 3 in the widened part 1c is considerably long, there is no possibility that it will protrude to the outer circumference of the tunnel. This has the benefit of increasing the subsequent excavation efficiency by expanding the crack width.

Furthermore, in the method of performing blasting after coring, the center portion 1b located further back than the widened portion 1c may also be blasted and cored at the same time as the widened portion 1c, and used for the next excavation method. good.

As explained above, the present invention provides a plurality of holes provided at predetermined intervals around the outer circumference of a planned tunnel excavation area.
Furthermore, since the plurality of holes provided in the widened portion are filled with an expandable sand-breaking agent as necessary, cracks are generated in the rock, so no over-excavation occurs during blasting. Also, since the rock to be excavated has cracks and has become brittle, only a small amount of explosives is needed for blasting.

Next, examples of the present invention will be shown.

Example 1 In a granite area, the upper half section radius is 2.3 m, and the lower half
During excavation work for a horseshoe-shaped tunnel that goes down 1.5m,
The outer circumference of the planned tunnel excavation area is 50mm in diameter and 2.5m in length.
Immediately after line drilling with a hole spacing of 30cm, apply an expansive crushing agent [Plystar (Onoda Cement Co., Ltd.)
After that, the hole diameter of the planned tunnel excavation area is
32mm hole length 1.5m, cored part 4 holes/m ² , widened part 3
Drill holes/m ² on average. At this time, the distance from the inside of the line drilling part to the widening part is 50 cm, and 2
Using Gono dynamite (100g/piece), the cored part is 8 pieces/the hole widened part is charged with 1 piece/hole that decreases as the distance from the cored part increases, and the rock is crushed in stages. As a result, there was hardly any excess excavation, and it was possible to destroy the rock in the area where the tunnel was to be excavated.

Example 2 In the construction of an advanced excavation tunnel with a radius of 2.5m in the upper half of a limestone area, the center was drilled with a V-cut, the core was removed using dynamite, and then the outer periphery of the planned tunnel excavation area was drilled with a hole diameter of 40cm in diameter. 50mm,
Line drilling was performed with a hole length of 3 m, and the widened part inside the line drilling was blasted.The hole diameter of the charge hole was 32 m.
Hole length 1.5m, expandable crushing agent filling hole spacing 50-70
Drill a hole with a length of 5 m and a hole diameter of 50 mm, immediately fill the line drilling part with an expanding crushing agent [Plystar (manufactured by Onoda Cement Co., Ltd.)], and after curing for 20 hours, fill the blasting charge hole with 5 holes/2 holes. Goen Dynamite (100
When a detonator was used to detonate the charge closer to the core part and detonate faster, the explosion occurred at 1.5 m.
At the same time, it became possible to excavate the rock to the depths, and at the same time, there was hardly any excess excavation outside the line drilling.
After that, after carrying out work such as shearing and shoring installation, the expanding crushing agent is generally filled deeper than the excavation depth by blasting in the line drilling part and widening part, so the next work is core blasting. Rock excavation work was carried out repeatedly, including drilling and blasting of blasting holes in the widening section. As a result, the amount of dynamite used could be reduced, and vibration noise could also be significantly reduced.

[Brief explanation of the drawing]

1 and 2 are explanatory front views showing embodiments of the present invention. In the drawings, 1 is a planned tunnel excavation area, 1a is an outer periphery, 1b is a cored part, 1c is a widened part, and 2 and 3 are holes.

Claims (1)

[Scope of Claims] 1. Line drilling is performed at predetermined hole gaps along the outer periphery of the planned tunnel excavation area, the drilled holes are filled with an expandable crushing agent, and after curing for a certain period of time, the tunnel is excavated from the hole. A tunnel excavation method characterized by performing blasting at a location a predetermined distance away from the center. 2. When blasting and coring the central part of the planned tunnel excavation area, small holes are drilled at regular intervals in the widened area around the cored part, and predetermined hole gaps are drilled along the outer periphery of the planned tunnel excavation area. Line drilling is performed each time, these holes are filled with an expandable crushing agent, and after curing for a certain period of time, blasting is performed at a location a predetermined distance away from the line drilling hole towards the center of the tunnel.
A tunnel excavation method characterized by excavating after or together with core removal.