JPH0480199B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to an underground cavity forming method, and in particular, when excavating a large cavity with a desired shape in underground rock, it is important not only to ensure safety during construction but also after excavating the cavity. This paper relates to a method for forming underground cavities that is reliable for maintaining stability.

Prior art and its problems It has become necessary to excavate large cavities deep underground in bedrock and use them for purposes such as storing oil, disposing or storing radioactive waste, and large machinery and equipment associated with energy supply.

Originally, when excavating a large cavity in deep underground bedrock, no matter how hard the rock is,
The enormous ground pressure that inevitably occurs must be controlled, and the utmost care and careful management are required for security during construction and for maintaining the stability of the cavity after excavation.

In the past, there have been cases in which large cavities remain underground as a result of the mining of valuable minerals, such as the remains of mining in massive metal deposits or the remains of underground glory hole mining in limestone mines. Attempts have been made to use these large cavities for purposes such as this, but not only are these large cavities geographically limited, but the shape of the cavities is determined by the type of mining, and there are difficulties in maintaining and preserving them. It has not yet reached the point where it is used.

Means for Solving the Problems An object of the present invention is to provide a method for forming a large cavity underground that has a desired shape and takes into account maintenance and management after the cavity is completed.

As a result of research to achieve the above purpose, the present inventor has
Basically, the middle stage mining method, which is known as a large-scale underground mining method in mines, is adopted as the underground cavity excavation method. By excavating a horizontal or nearly horizontal tunnel (hereinafter referred to as a contour tunnel) and a horizontal or nearly horizontal middle tunnel for drilling and drilling (hereinafter referred to as a middle tunnel) provided in the planned cavity, and by drilling and smooth blasting from these tunnels. The basic idea is to crush and remove the rock within the planned cavity. On the other hand, prior to these cavity excavation steps, in order to firmly stabilize the vicinity of the inner wall surface of the cavity, lock bolts are driven from a horizontal or nearly horizontal outer circumferential tunnel provided on the outer periphery further than the contour tunnel toward the planned cavity area. At the same time, a process of pre-spritting drilling and blasting is carried out between the contour tunnels so that the inner wall surface of the cavity is smooth, and as the cavity excavation process progresses, a hole is located above the planned cavity area. A step is carried out to support the cavity ceiling by charging solid material such as crushed slag from the outer tunnel into the cavity through the well and filling at least a part of the well with the solid material, and then The present inventors have discovered that the above object of the present invention can be achieved by moving to the cavity excavation step, and have arrived at the present invention.

Therefore, the method of the present invention, when forming a cavity underground by the middle stage mining method, (1) Driving lock bolts in the direction of the planned cavity from a plurality of peripheral shafts cut outside the periphery of the planned cavity. (2) A pre-spritting process in which pre-spritting drilling and blasting is performed from a cavity contour defined tunnel that is cut parallel to the outer tunnel at multiple locations around the planned cavity, (3) In the part where pre-spritting has been completed, among the middle level tunnels that have been drilled in parallel to the hollow contour defined tunnel at multiple locations,
(4) Smooth blasting process in which cavities are sequentially formed by drilling and blasting from the lower middle tunnel, and (4) solids are transported into the cavity through a well connected from the outer tunnel located above the planned cavity area. and a charging step of supporting the hollow ceiling by filling at least a portion of the well with the charged solids.

The configuration of the present invention will be explained below.

The basic cavity excavation method used in this invention is the middle-level mining method, which is known as a large-scale underground mining method used in mines. Compared to other underground mining methods, such as the upward mining method or the downward stepped mining method, this method means that the working area of the worker is isolated from the vast bare ceiling, which means there is a risk of the bare ceiling collapsing. This is because it is superior in terms of security because it can avoid this.

The shape of the underground cavity formed by the method of the present invention depends on the purpose of use as described above, for example, as shown in FIG. However, it is preferable that the cross-sectional shape of the cavity is polygonal in order to approximate the contour of the cavity to an oval or an ellipse, as it is an advantageous shape from the viewpoint of controlling the plate pressure. FIG. 1 shows an example of a preferable cross-sectional shape of a cavity according to the present invention, in which a contour tunnel is arranged at the apex position of a polygonal shape that is the cavity cross section, and a middle tunnel is arranged inside the planned cavity portion. Fan-shaped holes are made diagonally downward or directly below these tunnels, and cavities are formed by middle stage blasting.

In order to prevent the finished interior wall surface of the cavity from being damaged by large-scale blasting and furthermore from being damaged at an accelerated rate due to the strong ground pressure peculiar to deep rock that is constantly occurring, the walls of the contoured tunnel located at the apex of the polygon are located adjacent to each other. Pre-spritting will be carried out for the contour tunnel.

FIG. 2 is a perspective view of the intended cavity section having the cross-section shown in FIG. 1, in which a number of rows of pre-splitting holes parallel to each other along the contour of the cavity are shown in dotted lines.

By performing this pre-splitting, the inner wall surface of the cavity can be finished smoothly, and it also prevents cracks from forming and propagating on the outside of the cavity wall due to the influence of large-scale blasting from the middle tunnel.

Furthermore, before carrying out the above-mentioned large-scale blasting, lock bolts (cable bolts and other rock It is necessary to fix the parts that will become the cavity walls by pouring concrete (including those that are poured inside).

However, if the rock mass outside the periphery of the planned cavity is relatively strong, lock bolts may be installed after large-scale blasting if necessary.

If all the debris that has been crushed inside the planned cavity is pulled out through the excavation shaft cut below the planned cavity, the cavity will be ready in its proper shape, but since this is deep underground bedrock, careless debris may be removed. Extracting the material will have a negative effect on the self-sustainability of the cavity, and there is always a risk that work will not be able to continue even while excavation of the cavity is in progress. Unless a certain amount of the crushed waste is removed, it may not be possible to secure the necessary free surface for blasting to continue blasting in the middle stage, so the minimum amount must be removed, but as a result, the top surface of the crushed waste is separated from the cavity ceiling. Therefore, during the excavation period when the distribution of plate pressure is not determined, or for some time after the completion of excavation, an unexpected collapse of the roof may occur, and because the area is deep, there is a risk that a large-scale collapse may occur all at once.

Therefore, in the present invention, scraps are artificially introduced into the upper part of the cavity, and the hollow ceiling plate is supported by the crushed scraps at key points. That is, the outer circumferential tunnel (rock bolt drilling tunnel) located at the outer periphery of the top of the cavity.
Drill a well to introduce waste from the ground and inject waste.

In addition to using a portion of the waste that is carried to the surface through the waste extraction tunnel, it is also possible to use material that is separately brought in from the surface, or solidifying fluids such as cement paste, mortar, and concrete to provide temporary strength.

During cavity excavation, in addition to visual monitoring, we continue to monitor the plate pressure using instruments such as plate pressure gauges, extensometers, and AE (acoustic emission) counts, and use these to analyze the plate pressure state around the cavity and prevent slippage within the cavity. It is necessary to control so that the extraction and redistribution of plate pressure are performed smoothly and stably as appropriate.

It goes without saying that the monitoring system using these instruments will also play an extremely important role in maintenance and management after the cavity is completed.

Next, the present invention will be explained in more detail with reference to Examples.

Example A plurality of outer tunnels 3 parallel to the long axis of the planned cavity are excavated outside the periphery of the planned cavity having a polygonal cross section close to an approximately oval shape as shown in FIG. In order to protect and fix the parts that will become the wall surfaces, lock bolts 3a are driven from these outer tunnel groups as shown in the figure.

Next, each contour tunnel 1a, 1b, 1c, etc. located at the apex of the polygon defining the cross section of the planned cavity section is excavated, and a plurality of intermediate tunnels 6 are also excavated inside the planned cavity section, while each contour A pre-splatting drilling hole 2 is carried out from the tunnel to the adjacent contour tunnel.

As a result of the above, preparations for rock crushing in the planned hollow area by drilling and blasting from the middle level tunnel and contour tunnel have been completed.

Figure 3 shows a cross section in the longitudinal direction of the planned cavity, showing the outer tunnel 3 and lock bolts 3a installed in the ground on the left side of the drawing in the same way as in Figure 1, and the middle tunnel. As the rock is crushed by drilling and blasting from step 6 and cavities are successively formed, each middle tunnel will also retreat to the right in the drawing. The crushed waste 7 is carried out from the lower waste extraction shaft 4.

In order to prevent the upper surface of the crushed waste from separating from the cavity ceiling due to the removal of the crushed waste, the crushed waste or, if necessary, cement concrete is injected from the outer circumferential tunnel 3 above the cavity through the waste injection well group 5a, and cement concrete is injected into the cavity. The top plate is supported by a scraper.

FIG. 4 shows the above-mentioned method of introducing waste, in which solid matter 8 such as the above-mentioned waste introduced from the waste introduction well 5a is deposited on the crushed waste 7.

Effects of the Invention According to the method of the present invention, sufficient consideration has been given to the protection and stability of the inner wall surface of the cavity, especially the measures to prevent the collapse of the cavity ceiling, so that it is reliable not only during the cavity excavation work but also in maintenance and management after the cavity is completed. It is possible to form a large underground cavity with a desired size and shape.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of a longitudinal section of an underground cavity formed by the method of the present invention, and FIG. 2 is a perspective view showing a row of pre-spritting perforations in a planned cavity section having the cross section shown in FIG. 1. It is a diagram. Figure 3 shows a cross section of an underground cavity formed by the method of the present invention.
A schematic diagram showing an example, FIG. 4 is a schematic sectional view showing a process of carrying solid matter through a well from an outer tunnel located above a planned cavity part and supporting a cavity ceiling. FIG. 5 is a bird's-eye view showing a tunnel-type underground cavity (Figure A) formed by the method of the present invention or an example in which these are connected in a ring (Figure B). 1a, 1b, 1c...Cavity contour defined tunnel, 2...
...Drilling hole for pre-spritting, 3...Outer tunnel, 3a...Rock bolt, 4...Damage extraction tunnel, 5a, 5b...Solid material injection well, 6...Middle tunnel, 7...Upgrading waste, 8...Solid matter.

Claims (1)

[Scope of Claims] 1. When forming a cavity underground by the middle stage mining method, (1) lock bolts are driven in the direction of the planned cavity from a plurality of peripheral shafts cut outside the periphery of the planned cavity; (2) A pre-spritting process in which pre-spritting drilling and blasting is performed from a cavity contour defined tunnel that is drilled parallel to the outer tunnel at multiple locations around the planned cavity; (3) Multiple locations within the planned cavity. In the part of the perforated middle tunnel that was drilled parallel to the cavity contour defined tunnel in 2015, pre-spritting was completed.
(4) Smooth blasting process in which cavities are sequentially formed by drilling and blasting from the lower middle tunnel, and (4) solids are transported into the cavity through a well connected from the outer tunnel located above the planned cavity area. A method for forming an underground cavity, characterized by comprising the steps of: charging the solid material into the well, and supporting the cavity ceiling by filling at least a portion of the well with the charged solid material.