LU500342B1 - Method for Reducing Surface Subsidence Range of Underground Mining Area - Google Patents

Abstract

The invention discloses a method for reducing the surface subsidence range of an underground mining area. It comprises the following steps: 1. Acquiring the position of underground mining working, the advancing direction and speed of the working and the influence range of surface subsidence on the periphery of a projection area of the mining working area; 2. According to the advancing direction and speed of the working face, predict the scope and time of surface subsidence, and divide the tension zone and tension extrusion zone within the potential subsidence range; 3. Before the surface subsidence, arrange drilling holes and carry out controlled blasting in the potential tension extrusion area, or directly dig grooves; 4. Repeat the above steps after the surface subsidence comes.

Description

DESCRIPTION Method for Reducing Surface Subsidence Range of Underground Mining Area

TECHNICAL FIELD The invention relates to a technology for preventing and controlling surface geological disasters and protecting ecological environment in underground mining areas, in particular to a method for effectively reducing the surface subsidence range of mined-out areas and protecting the structures above the ground.

BACKGROUND Mine geological disasters in China are very serious, and land subsidence caused by underground mining is one of the most common types of mine geological disasters in mining areas. In plain mining areas, ground subsidence not only causes the destruction of ground houses, traffic facilities, dams and other structures, but also causes the decline of land quality or the destruction of land resources in mining areas.

According to the characteristics of surface subsidence and deformation in underground mining area, the subsidence of soil has a traction and stretching effect on the periphery, which also causes a certain degree of subsidence to the earth in a certain range beyond the projection of the surface of the mining area. The surface subsidence area around the mining area is often larger than the actual underground mining area. Figure 1 is a schematic diagram of plane distribution of subsidence area of surface subsidence basin in underground mining area. In this figure, the sum of subsidence areas AD and EB located on both sides of the projection area of the working face is much larger than DE.

It can be seen from the profile figure 2 of mining subsidence basin that during the formation of surface subsidence basin, the soil on the slope of the basin will be pulled or stretched from the subsidence area in the center of the basin in the early stage. In the middle and late period of basin development, this traction and stretching action gradually weakened; On the contrary, the soil on the upper part of the slope is pushed from top to bottom. At this time, the middle and lower part of the basin slope is in compression state, while the middle and upper part is in tension state. Therefore, during the basin formation, the slopes CD and EF always suffer from traction, tension or compression stress.

The purpose of the invention is to control the basin subsidence range in the CF section of the expected subsidence area according to the principle of engineering mechanics.

At present, the main method to control or reduce the land subsidence in mining areas 1s mining. For example, the insufficient mining and filling mining of the seam, so as to reduce the land subsidence amplitude of the mining area; Secondly, grouting of key layers on the ground. These methods cannot be widely used because of their complex process and high cost. Therefore, it is urgent for those skilled in the art to provide a method that can achieve or mostly achieve the desired goal in Figure 1.

SUMMARY The purpose of the invention is to overcome the defects of the prior art, provide a method for reducing the surface subsidence range of mined-out area, and solve the technical problem that the subsidence range is too large due to the traction and stretching of the underground mined-out area to the soil around the surface in the prior art. The invention 1s realized by the following technical scheme: The invention relates to a method for reducing the surface subsidence range of an underground mining area, which comprises the following steps: Step 1: Acquiring the position of underground mining work, the working advancing direction and speed, and the depth of the vadose zone; Step 2: Predicting the surface subsidence range and time according to the information obtained in step 1. Dividing the subsidence range into an underground goaf direct caving subsidence area, a tension extrusion subsidence area and a tension subsidence area from inside to outside: Step 3: Before the time point of surface subsidence, drilling and blasting are carried out at the joint of the tension extrusion subsidence area and the tension subsidence area to form a partition groove, or the groove is directly excavated; Step 4: Repeat the above steps after the time point of surface subsidence comes at this stage.

Further, in step 3, the drilling goes through the vadose zone of the topsoil during drilling blasting, and the drilling spacing should be controlled within the range where cracks can penetrate each other after blasting between adjacent drilling holes.

Further, when the trench 1s excavated directly in step 3, the depth of the trench is not less than the depth of the vadose zone of the topsoil, and the width of the trench is not less than 1m.

Compared with the prior art, the invention has the following advantages: The invention provides a method for reducing the surface subsidence range of an underground mining area, which comprises the following steps of: drilling holes and carrying out controlled blasting on the periphery of the surface projection of an underground working face before the surface subsidence time point, so that a fracture occurs between the surface projection area of the mining area and the periphery soil body, so that when the subsidence time point arrives, the surface projection to be subsided is sinking, and the stretching of the periphery soil body is weakened or even disappeared, thereby greatly weakening the influence of dragging the periphery soil body to deform when sinking, further effectively reducing the scope of the subsidence area and realizing or most realizing the surface.

It can reduce the damage of surface environment caused by mining, such as village relocation and destruction of structures. Reduce the danger of geological disasters in mining areas and improve the land use efficiency in mining areas. The method has the characteristics of concise technical steps, simple operation, low cost and remarkable effect. It is applicable to coal mines and other non-metallic and metal mines.

BRIEF DESCRIPTION OF THE FIGURES Figure 1 is a schematic diagram of surface subsidence range and expected subsidence range in mining area.

Figure 2 is a schematic cross-sectional view of the surface subsidence range in the mining area shown in figure 1.

DESCRIPTION OF THE INVENTION In order to make the skilled better understand the scheme of this application, the technical scheme of this application will be described clearly and completely with reference to the example of this application. Obviously, the described example 1s only a part of this application, not all embodiments. Based on the example in this application, all other embodiments obtained by ordinary technicians in this field without creative labour should belong to the protection scope of this application.

It should be noted that the term "including" in the specification and claims of this application is intended to cover non-exclusive inclusion. For example, a method including a series of steps need not be limited to those steps explicitly listed, but may also include other steps not explicitly listed or inherent to these methods. The embodiments in this application and the features in the embodiments can be combined with each other without conflict. The application will be described in detail below with reference to example.

Example Referring to figure 1 and figure 2, it can be seen that in the prior art, the area of ground subsidence after mining in the underground working area is much larger than the actual mining area. Even if the ground above the mining area is cultivated land without buildings, the ground will suffer from tensile cracking. It will lead to the decline of soil quality and the destruction of ecological environment. Because of this, in order to exploit underground mineral resources to a greater extent, mining enterprises have to spend a lot of money to relocate villages or protect important structures or adopt filling mining technology. These will greatly increase the mining cost.

To sum up, in this example, in order to reduce the subsidence range caused by mining and make the safe subsidence range after mining reach or mostly reach the desired subsidence area, the following method is adopted: The invention relates to a method for reducing the surface subsidence range of an underground mining area, which comprises the following steps: Step 1: Acquiring the position of an underground mining working area, the advancing direction and speed of the working area, and the depth of the vadose zone of the topsoil, Step 2: Predicting the surface subsidence range and time according to the information obtained in step 1, and dividing the subsidence range into a goaf direct caving subsidence area, a stretching extrusion subsidence area and a stretching subsidence area from inside to outside; Step 3: Before the time point of surface subsidence, drilling and blasting are carried out at the joint of the tension extrusion subsidence area and the tension subsidence area to form a partition groove, or the groove is directly excavated,

Step 4: Repeat the above steps after the time points of surface subsidence come.

In the step 3, the drilling goes through the vadose zone of the topsoil during drilling blasting, and the drilling spacing should be controlled within the range where cracks can penetrate each other after blasting between adjacent drilling holes.

When the trench is excavated directly in step 3, the depth of the trench is not less than the depth of the vadose zone of the topsoil, and the width of the trench is not less than 1m.

Among them, in step 1, the position, advancing direction and speed of the underground mining face, the depth of the surface vadose zone and the influence range of the surface subsidence around the projection area of the working face are all determined by investigation; The location of surface projection and subsidence range can be determined by the location of underground mining face. According to the advancing direction and speed of the working face, the time point of surface subsidence can be determined. The distribution range of tensile subsidence area and compressive tensile subsidence area is obtained through the early mining data of the mining area or according to the mining geological condition data calculation and ground investigation; After the underground mining range is determined, the physical and mechanical properties of soil in the subsidence range can be tested synchronously. If there is rock mass on the ground surface in the subsidence area, its physical and mechanical properties can be analysed synchronously to prepare for setting blasting parameters later.

Surface subsidence depends on the speed of underground mining, and shows periodic development. Therefore, drilling and blasting or grooving the area to be sunk before the subsidence can effectively cut off the drag or traction force between the soil in the subsidence range (i.e., the soil CF in the desired subsidence area in fig. 1) and the soil in the peripheral control area (i.e., AC and FB in fig. 1). This is equivalent to relatively isolating the surrounding soil, thus controlling the deformation of the surrounding soil when the subsidence time comes, and then achieving the purpose of reducing the subsidence range.

The above example only illustrates the technical concept and characteristics of the present invention. The purpose is to make the skilled familiar with this technology understand the content and implementation of the present invention. It cannot limit the scope of protection of the present invention. All equivalent changes or modifications made according to the spirit of the present invention should be covered within the scope of protection of the present invention.

It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be realized in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, the embodiments should be regarded as exemplary and non-limiting from any point of view, and the scope of the present invention is defined by the appended claims rather than the above description, so it is intended to embrace all changes falling within the meaning and range of equivalent elements of the claims.

In addition, it should be understood that although this specification is described according to embodiments, each embodiment does not contain only one independent technical solution. The description of this specification is only for the sake of clarity, and those skilled in the art should take the specification as a whole. The technical solutions in each embodiment can also be combined appropriately to form other embodiments that can be understood by those skilled in the art.

The present invention is not limited to the above description of the example. The improvements and modifications made by those skilled in the art based on the disclosure of the present invention without creative labour should be within the protection scope of the present invention.

Claims (3)

CLAIMS:

1. A method for reducing the surface subsidence range of underground mining areas, which 1s characterized by comprising the following steps: Step 1: acquiring the position of an underground mining working area, the advancing direction and speed of the working face, and the depth of the vadose zone of the topsoil; Step 2: predicting the surface subsidence range and time according to the information obtained in step 1; dividing the subsidence range into a goaf direct caving subsidence area, a stretching extrusion subsidence area and a stretching subsidence area from inside to outside: Step 3: before the time point of surface subsidence, drilling and blasting are carried out at the joint of the tension extrusion subsidence area and the tension subsidence area to form a partition groove, or the groove is directly excavated; Step 4: repeat the above steps after the time point of surface subsidence comes at this stage.

2. The method according to claim 1, characterized in that in the step 3, the drilling depth goes through the vadose zone of the topsoil during drilling blasting, and the drilling spacing should be controlled within the range where cracks can penetrate each other after blasting between adjacent drilling holes.

3. The method according to claim 1 or 2, characterized in that, when the trench is directly excavated in step 3, the depth of the trench 1s not less than the depth of the vadose zone of the topsoil, and the width of the trench is not less than 1m.