JPS63251600A - Method of forming underground cavity - Google Patents

Abstract

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

Description

DETAILED DESCRIPTION OF THE INVENTION 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 necessary not only for security during construction but also for maintaining stability after excavation of the cavity. Concerning a reliable underground cavity formation method.

It has become necessary to excavate large cavities deep underground in bedrock and use them to store oil, dispose of or store radioactive waste, and supply energy to mechanical equipment.

Originally, when excavating a large cavity in deep underground bedrock, no matter how hard the rock is, it is necessary to control the strong ground pressure that inevitably occurs, and it is necessary to control security during construction and cavity excavation. Careful attention and careful management are required to maintain the stability of the cavity afterwards.

In the past, there have been examples of large cavities remaining underground as a result of the completion of mining of valuable minerals, such as mining sites in massive metal deposits or underground glory hole mining sites in limestone mines. Attempts have been made to use these large cavities for the above purposes, but these large cavities are limited to certain regions, and the shape of the cavities depends on the type of mining, making maintenance difficult. However, it has not yet been put to use.

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 object, the present inventor adopted the middle stage mining method, which is basically known as a large-scale underground mining method in mines, as an underground cavity excavation method. A plurality of horizontal or nearly horizontal tunnels located on the periphery of the cavity to define the outline of the cavity (hereinafter referred to as contour tunnels), and a horizontal or nearly horizontal intermediate tunnel for drilling provided within the planned cavity area (hereinafter referred to as middle tunnel) The basic idea is to excavate the tunnels and crush and remove the rock within the planned cavity area by drilling and smooth blasting from these tunnels. On the other hand, prior to these cavity excavation processes, in order to strongly stabilize the vicinity of the inner wall surface of the cavity, rock bolts were driven from the horizontal or nearly horizontal peripheral tunnel provided further outside the contour tunnel in the direction of the planned cavity area. At the same time, a process of pre-splitting 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, the outer periphery located above the planned cavity area is A process is carried out in which a solid material such as crushed grinding sludge is charged into the cavity from the tunnel through the well, and the solid material fills at least a part of the well to support the cavity ceiling, and then the cavity top plate is supported. The inventors have discovered that the above object of the present invention can be achieved by proceeding to the process, and have arrived at the present invention.

Therefore, in the method of the present invention, when forming a cavity underground by the middle stage mining method, (1) rock bolts are driven in the direction of the planned cavity from a plurality of peripheral tunnels excavated outside the periphery of the planned cavity; (2) A pre-splitting process in which pre-splitting drilling and blasting is carried out from a cavity contour defined tunnel drilled at multiple locations around the circumference of the planned cavity in parallel to the outer tunnel; (3) Cavity contour defined at multiple locations within the planned cavity. A smooth blasting process in which a cavity is sequentially formed by drilling and blasting from the lower middle-level tunnel in the part where pre-splitting has been completed in a middle-level tunnel drilled in parallel with the tunnel, and (4) a planned cavity area. The solid material is charged into the cavity through an FC well connected to the cavity from a peripheral tunnel located above,
The charged solids fill at least a portion of the wellbore;
A charging step of supporting the hollow top plate by the steps of: 0 The present invention will be described in detail below.

As the basic cavity excavation method in this invention, the middle stage mining method, which is known as a large-scale underground mining method in mines, is adopted. 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.
Tunnel shape (Figure A) or a ring-shaped shape (
Although the shape can be freely selected from the shape shown in Fig. B), it is preferable to make the cross-sectional shape of the cavity polygonal in order to approximate the outline of the cavity to an oval or 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 inner walls of the cavity from being damaged by large-scale blasting and furthermore, from being damaged at an accelerating rate due to the strong ground pressure unique to deep rock that occurs constantly, a contoured tunnel is located at the apex of the polygon. Pre-splitting will be carried out from each to the adjacent contour tunnel.

FIG. 2 is a perspective view of the cavity section having the cross-section shown in FIG. 1, with a number of parallel pre-splitting rows of perforations along the contour of the cavity shown in dotted lines.

By applying 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, rock bolts C-- were drilled into the rock outside the periphery of the planned cavity from a plurality of outer tunnels that were cut approximately parallel to the long axis of the cavity. It is necessary to fix the part that will become the cavity wall by driving pull bolts (including pull bolts and other bolts driven into the rock).

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

If the debris that was crushed within the planned cavity area is excavated below the planned area and pulled out completely through the FCJIJ tunnel, the hollow shape will be ready, but since it is deep underground in the bedrock, carelessly Removing the sludge 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 crushed debris is removed, it may not be possible to secure the necessary blasting free surface for continuing middle-stage blasting, and the minimum amount of debris must be removed. Because they are separated, unexpected collapse of the roof may occur during the excavation period when the distribution of plate pressure is not determined or for some time after the completion of excavation, and because it 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, from the outer tunnel (rock bolt drilling tunnel) located on the outer periphery of the top of the cavity, a well is excavated to introduce y', and the y' is injected into the well.

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 drilling, in addition to visual monitoring, plate pressure gauges, extensometers, and AE
(aco%atic amiaaion) We will continue to monitor the plate pressure using instruments such as counters, analyze the plate pressure state around the cavity, pull out gaps in the cavity as appropriate, and redistribute the plate pressure smoothly and stably. It is necessary to control the situation so that the

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 oval shape as shown in FIG. In order to protect and fix the parts that will become the wall surfaces over the period, rock bolts 3α are driven from these outer tunnel groups as shown in the figure.

Next, each contour tunnel 1α, 1b, 1c, . Pre-splitting drilling 2 is carried out from each contour 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 of the planned cavity in the longitudinal direction.
, the outer tunnel 3 and rock bolts 3cL installed in the ground on the left side of the drawing are shown in the same way as in FIG. Accordingly, the valley middle tunnel will also retreat to the right in the drawing.

The hardened waste 7 is carried out from the lower waste extraction tunnel 4. In order to prevent the upper surface of the hardened waste from separating from the cavity ceiling due to the removal of the hardened waste, a waste injection well is carried out from the outer circumferential tunnel 3 above the cavity. Cement concrete is poured into the gap or as necessary through group 5a, and the hollow ceiling is supported by IJ.

FIG. 4 shows the method for reinserting the sludge 1, in which solid matter 8 such as the sludge introduced from the sludge injection well 5G is deposited on the hardened sludge 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, and in particular to the prevention of collapse of the cavity ceiling, so that it is reliable not only during the excavation work of the cavity but also for maintenance and management after the completion of the cavity. It is possible to form a large-scale underground cavity according to the desired scale and shape.

[Brief explanation of drawings]

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 pre-splitting perforation row in a planned cavity section having the cross section shown in FIG. 1. be. Fig. 3 is a schematic diagram showing an example of a cross section of an underground cavity formed by the method of the present invention, and Fig. 4 is a schematic diagram showing an example of a cross section of an underground cavity formed by the method of the present invention. FIG. 3 is a schematic cross-sectional view showing a process of supporting the board. Figure 5 shows a tunnel type (Figure A) as an underground cavity formed by the method of the present invention or an example of a ring-shaped underground cavity (Figure B).
It is a bird's eye diagram showing the figure. 1a, 1b, 1G...: Cavity contour defined tunnel 2
:Drilling hole 3 for press plyzing
: Peripheral tunnel 3G - Rock bolt 4 : Sludge extraction tunnel 5α, 5b... : Solid material input well 6
: Middle tunnel 7 : Hardening waste 8 : Solid matter

Claims (1)

[Claims] When forming a cavity underground by the middle stage mining method, (1) a lock in which rock bolts are driven in the direction of the planned cavity from a plurality of peripheral tunnels cut outside the periphery of the planned cavity; bolting process, (2) pre-spritting process in which pre-split drilling and blasting are performed from a cavity contour defined tunnel drilled parallel to the outer tunnel at multiple locations on the periphery of the planned hollow area, (3) multiple locations within the planned hollow area. A smooth plasting process in which holes are sequentially formed by drilling and blasting from the lower boring middle tunnel in the part where pre-spritting has been completed in the hollow middle tunnel drilled parallel to the hollow contour defined tunnel; and (4) charging solids into the cavity through a well connected to the cavity from a peripheral tunnel located above the planned cavity, and filling at least a portion of the well with the charged solids. A method for forming an underground cavity, characterized by comprising the steps of: a charging step of supporting a cavity top plate;