A method for preventing casing breakage in mines

Abstract

The present invention discloses a method for preventing casing breakage in underground mines, the steps of which include constructing a plurality of pressure relief boreholes around the original boreholes where casing breakage needs to be prevented, and using a plurality of anchor cables to anchor the surrounding rock around the original boreholes outside the pressure relief boreholes, so as to ensure that the anchor cable heads are anchored on stable rock formations. After adopting this method, when the tunnel is deformed and the bottom bulges due to ground stress, the pressure relief boreholes can increase the deformation capacity of the rock formations around the casing, strengthen the anchoring force of the anchor cables, and reduce the deformation of the rock formations around the casing, thereby reducing the deformation of the surrounding rock and the influence of the deformation on the casing, so as to prevent the casing from breaking. In addition, when this method is applied, the borehole can be used normally.

Description

Technical Field

[0001] The invention relates to the field of underground mine safety, and in particular to a method for preventing casing breakage in an underground mine. Background Art

[0002] A large number of boreholes are constructed underground in mines for aquifer level monitoring, geological structure detection, aquifer water-rich condition detection, geological disaster control, etc. For example, for boreholes constructed for mine water prevention and control, according to the Coal Mine Safety Regulations and Coal Mine Water Prevention and Control Regulations, in order to ensure the safety of the construction process and controllability of the drilling process, casing is required to be installed in the boreholes, and the casing length is strictly regulated according to the water pressure data of the detected aquifer.

[0003] The casing is generally a steel pipe, which is connected by threads in sections. The casing and the surrounding rock of the hole wall are often consolidated together with cement slurry. In recent years, casing fractures have occurred from time to time. For example, the casing of the O2-7 hole in the Xinglongzhuang Coal Mine underground ash water level monitoring hole suddenly broke, the water out of the borehole could not be controlled, and the total water inflow of the mine suddenly increased, causing a tense drainage situation. According to research and detection, the casing fracture is mainly caused by the deformation of the surrounding rock of the tunnel and the development of the loose circle. The fracture position is generally at the edge of the loose circle. The thickness of the loose circle is generally between 0.5-1.0 times the width of the tunnel. For example, the width of the tunnel is 5m, and the thickness of the loose circle is generally 2.5-5m. The fracture position of the drilling casing in the tunnel is between 2.5-5m. Summary of the invention

[0004] In view of the above-mentioned technical deficiencies, the purpose of the present invention is to provide a method for preventing the breakage of underground mine casing, which adopts the idea of ​​combining pressure relief and reinforcement, internal relief and external reinforcement, and is mainly used to prevent the breakage of existing underground borehole casing. The principle is simple, the operation is convenient, safe and effective.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] The present invention provides a method for preventing casing breakage in a mine, comprising the following steps:

[0007] S1. Construct several pressure relief holes around the original borehole where casing breakage needs to be prevented, so as to weaken the connection between the casing and the surrounding rock. The direction of the pressure relief holes is consistent with that of the original boreholes and the depth of the holes exceeds the width of the tunnel where the original boreholes are located.

[0008] S2. Use several anchor cables to anchor the surrounding rock around the original borehole outside the pressure relief borehole to reduce the deformation of the surrounding rock of the tunnel around the casing. The extension direction of the anchor cable hole is consistent with the direction of the original borehole and its depth is more than 1.5 times the width of the tunnel to ensure that the anchor cable head is anchored on a stable rock formation.

[0009] Preferably, it is characterized in that the diameter of the pressure relief drilling hole in step S1 is 28-42 mm, and the depth of the pressure relief drilling hole exceeds the width of the tunnel where the original drilling hole is located by 0.5 m.

[0010] Preferably, it is characterized in that the extension direction of the pressure relief drilling hole in step S1 is consistent with the direction of the original drilling hole. Under the condition of avoiding the orifice flange and valve of the original drilling hole, the opening point of the pressure relief drilling hole is as close to the casing as possible and arranged in multiple circles. The spacing between the pressure relief drilling holes is controlled at 10±0.5cm.

[0011] Preferably, it is characterized in that in step S2, the anchor cable is a conventional mining steel anchor cable, and is anchored at the end with a resin anchoring agent.

[0012] Preferably, it is characterized in that the number of anchor holes in step S2 is determined comprehensively according to the magnitude of the tunnel floor heave, the pull-out resistance of the anchor cables used, and the ground pressure environment of the tunnel, and the anchor cable spacing is controlled at 0.5-1.0m.

[0013] The beneficial effect of the present invention is that after adopting this method, when the tunnel is deformed and the bottom bulges due to ground stress, the pressure relief drilling can increase the deformation capacity of the rock formation around the casing, strengthen the anchoring force of the anchor cable, and reduce the deformation of the rock formation around the casing, thereby reducing the deformation of the surrounding rock and the influence of the deformation on the casing to prevent the casing from breaking. In addition, when this method is applied, the drilling can be used normally. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0015] Figure 1 A schematic diagram of the location of the pressure relief drilling hole provided in an embodiment of the present invention.

[0016] Description of reference numerals:

[0017] 1. Pressure relief drilling hole; 2. Anchor cable; 3. Casing. DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] like Figure 1 As shown, a method for preventing casing breakage in a mine includes the following steps:

[0020] S1. Use an anchor drill to construct several pressure relief holes 1 around the original borehole where the casing 3 needs to be prevented from breaking, mainly to weaken the connection between the casing 3 and the surrounding rock of the formation;

[0021] The diameter of the pressure relief borehole 1 is 28-42 mm. The depth of the pressure relief borehole 1 needs to exceed the width of the tunnel where the casing 3 is located to prevent the casing 3 from breaking, preferably more than 0.5 m. For example, if the tunnel width is 4 m, the depth of the pressure relief borehole 1 is 4.5 m.

[0022] The extension direction of the pressure relief drill hole 1 is consistent with the direction of the original drill hole. Under the condition of avoiding the flange and valve of the original drill hole, the opening point of the pressure relief drill hole 1 is as close to the casing 3 as possible, and a multi-circle arrangement is adopted. The spacing of the pressure relief drill holes 1 is controlled at 10 cm to prevent the pressure relief drill holes from being skewed and connected during the drilling process, which may cause the pressure relief drill holes to be stuck and unable to form holes.

[0023] S2. Outside the pressure relief borehole 1, at a position farther from the casing 3, anchor cables 2 are used to anchor the surrounding rock around the original borehole to reduce the deformation of the surrounding rock in the tunnel around the casing 3 (the bottom plate is mainly bottom drum, and the tunnel is convergent).

[0024] The extension direction of the anchor hole is consistent with the original drill hole. The anchor hole is constructed with an anchor drilling rig. The depth of the anchor hole must be more than 1.5 times the width of the tunnel to ensure that the anchor head is anchored on a stable rock formation.

[0025] The anchor cable 2 uses conventional mining steel anchor cables and is anchored at the end with a resin anchor. The number of anchor cable holes is determined based on the magnitude of the tunnel floor heave, the pull-out resistance of the anchor cable 2 used, and the ground pressure environment of the tunnel. The spacing between anchor cables 2 is controlled at 0.5-1.0m.

[0026] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for preventing casing breakage in a mine, characterized in that: The following steps are involved: S1. Constructing a number of pressure relief holes (1) around the original borehole where the casing (3) needs to be prevented from breaking, so as to weaken the connection between the casing (3) and the surrounding rock of the formation. The direction of the pressure relief holes (1) is consistent with the direction of the original borehole and the hole depth exceeds the width of the tunnel where the original borehole is located; S2. A plurality of anchor cables (2) are used outside the pressure relief borehole (1) to anchor the surrounding rock around the original borehole, thereby reducing the deformation of the surrounding rock of the tunnel around the casing (1). The extension direction of the anchor cable hole is consistent with the direction of the original borehole and its depth is more than 1.5 times the width of the tunnel, ensuring that the anchor cable head is anchored on a stable rock formation.

2. A method for preventing casing breakage in a mine as claimed in claim 1, characterized in that: In step S1, the diameter of the pressure relief drill hole (1) is 28-42 mm, and the depth of the pressure relief drill hole (1) exceeds the width of the tunnel where the original drill hole is located by 0.5 m.

3. A method for preventing casing breakage in a mine as claimed in claim 1, characterized in that: In step S1, the extension direction of the pressure relief drill hole (1) is consistent with the direction of the original drill hole. While avoiding the orifice flange and valve of the original drill hole, the opening point of the pressure relief drill hole (1) is as close to the casing (3) as possible and is arranged in multiple circles. The spacing between the pressure relief drill holes (1) is controlled to be 10±0.5cm.

4. A method for preventing casing breakage in a mine as claimed in claim 1, characterized in that: The anchor cable (2) is a conventional mining steel anchor cable, and is anchored at the end with a resin anchoring agent.

5. A method for preventing casing breakage in a mine as claimed in claim 1, characterized in that: The spacing between anchor cables (2) is controlled at 0.5-1.0m.

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