A method for active prevention and treatment of floor heave in a coal mine roadway intersection type grouting net

Abstract

The present application belongs to the technical field of mine roadway mining maintenance control, and discloses a coal mine roadway cross type grouting net active prevention and treatment of floor heave method, comprising the following steps: based on stress determination and roadway surrounding rock deformation monitoring data, identifying and dividing the roadway area with soft floor or residual coal floor; at the two bottom corners of the roadway area, respectively, a plurality of large-diameter partition drill holes are drilled obliquely downward; hole brushing and diameter expanding operation is carried out at the bottom of the large-diameter partition drill hole, so that the bottom of the large-diameter partition drill hole forms a pressure relief cavity; water is injected into the large-diameter partition drill hole and the pressure relief cavity, and after water injection, waste gangue is filled into the large-diameter partition drill hole and the pressure relief cavity; at the bottom of the roadway area, a plurality of grouting drill holes are drilled obliquely into the internal part of the roadway floor and grout is injected, and the plurality of grouting drill holes constitute a grouting net. The present application is simple in construction, low in cost, can increase the strength of the soft floor of the roadway, and improve the stability of the roadway floor.

Description

Technical Field

[0001] This invention belongs to the field of mine roadway mining, maintenance and control technology, and particularly relates to a method for actively preventing floor heave in coal mine roadways using a cross-type grouting net. Background Technology

[0002] Currently, most coal mines face mining environments characterized by high ground pressure, high stress, and high ground temperature. With increasing mining depth, the stable maintenance of mining roadways becomes particularly important. Damage to mining roadways can generally be categorized into roof damage, sidewall damage, and floor damage. Floor damage not only affects coal transportation and equipment storage but, more seriously, can disrupt normal mine operations, causing significant economic losses. Floor damage often manifests as floor heave, which occurs when stress is transferred from the roof and floor to the floor, causing it to bulge upwards. Floor heave reduces the roadway cross-section, obstructs transportation and pedestrian access, hinders mine ventilation, and in severe cases, renders the entire roadway unusable, significantly restricting mine production and safety.

[0003] Methods for preventing floor heave in roadways mainly include post-heave treatment and pre-heave prevention. Post-heave treatment often employs passive methods, involving "removing" the bulging portion of the roadway floor. This typically requires multiple removals and cannot completely stop the heave. Removing the floor is not only labor-intensive and costly but also affects the stability of the sidewalls and roof strata. Another method involves replacing weak sections of the roadway floor with precast structures. Currently, various types of anti-heave structures are commonly used to strengthen the floor and prevent further heave. Pre-heave prevention methods are primarily active, including floor grouting and floor support to reinforce the roadway floor, increasing its resistance to deformation and thus protecting it. However, the above prevention and control methods all have different drawbacks and shortcomings. For example, passive prevention and control methods are carried out after the roadway is damaged. On the one hand, this delays the normal operation of coal mining. On the other hand, the amount of bottom-removal work is large, requiring a lot of manpower and material resources, and the bottom protection effect is not obvious. Active prevention and control methods require a large amount of support materials to reinforce the roadway floor, which is costly, and the support materials are difficult to recycle after the roadway is abandoned.

[0004] Therefore, there is an urgent need for a method to actively prevent floor heave in coal mine roadways using cross-grouting mesh, in order to solve the above problems. Summary of the Invention

[0005] The purpose of this invention is to provide a method for actively preventing floor heave in coal mine roadways using cross-type grouting nets, in order to solve the problems existing in the prior art.

[0006] To achieve the above objectives, the present invention provides the following solution: The present invention provides a method for actively preventing floor heave in coal mine roadways using a cross-grouting mesh, comprising the following steps: Based on stress measurement and roadway surrounding rock deformation monitoring data, roadway areas with weak floor or residual coal floor are identified and delineated. At the two bottom corners of the tunnel area, multiple large-diameter partition holes are drilled diagonally downwards. A hole-enlarging operation is performed at the bottom of the large-diameter partition borehole to form a pressure relief cavity at the bottom of the large-diameter partition borehole. Water is injected into the large-diameter partition borehole and the pressure relief cavity, and then waste gangue is filled into the large-diameter partition borehole and the pressure relief cavity. At the bottom of the tunnel area, multiple grouting holes are drilled obliquely into the tunnel floor and grout is injected, forming a grouting network.

[0007] According to the present invention, a method for actively preventing floor heave in coal mine roadways using cross-type grouting mesh is provided, wherein the diameter of the large-diameter partition borehole is 100mm-110mm, and the distance between two adjacent large-diameter partition boreholes is 1300mm-1700mm.

[0008] According to the present invention, a method for actively preventing floor heave in coal mine roadways using a cross-type grouting mesh is provided, wherein the axis of the large-diameter isolation borehole has an angle of 5°-10° with the vertical direction, and the deflection direction points to the outside of the roadway area.

[0009] According to the present invention, a method for actively preventing floor heave in coal mine roadways using cross-type grouting mesh is provided, wherein the diameter of the grouting borehole is 50mm-73mm.

[0010] According to the present invention, a method for actively preventing floor heave in coal mine roadways using cross-type grouting mesh is provided, wherein the projected length of the grouting borehole is 1 / 2 of the roadway cross-sectional width.

[0011] According to the present invention, a method for actively preventing floor heave in coal mine roadways using a cross-type grouting mesh is provided, wherein four adjacent grouting holes form a rhombus-shaped grouting mesh unit, and multiple rhombus-shaped grouting mesh units form the grouting mesh.

[0012] According to the present invention, a method for actively preventing floor heave in coal mine roadways using a cross-type grouting mesh is provided. The four grouting holes in the rhomboid grouting mesh unit are divided into two groups and symmetrically arranged at the floor position of the roadway area. The distance between the two grouting holes in the same group is 500mm, and the distance between the grouting holes in each group and the corresponding side coal wall of the roadway area is 500mm.

[0013] According to the present invention, a method for actively preventing floor heave in coal mine roadways using a cross-type grouting mesh is provided, wherein the grouting boreholes are arranged around the large-diameter partition boreholes, and the two grouting boreholes in the same group and the adjacent large-diameter partition boreholes are distributed in a plane as equilateral triangle vertices.

[0014] According to the present invention, a method for actively preventing floor heave in coal mine roadways using a cross-type grouting mesh is provided, wherein the angle between the grouting borehole and the roadway floor plane in the vertical direction is 20°-40°, and the angle between the grouting borehole and the line connecting the center of the roadway cross section in the horizontal direction is 20°-35°.

[0015] According to the present invention, a method for actively preventing floor bulging in coal mine roadways using a cross-type grouting mesh is provided, wherein the openings of the large-diameter isolation borehole and the grouting borehole are sealed.

[0016] Compared with the prior art, the present invention has the following advantages and technical effects: This invention provides a method for actively preventing floor heave in coal mine roadways using a cross-grouting network. In development roadways, preparation roadways, and mining roadways, based on stress measurement and roadway surrounding rock deformation monitoring data, the roadway floor areas and damage ranges with weak or residual coal bottoms are determined and demarcated. Within the demarcated damage range or roadway areas prone to floor heave, large-diameter isolation boreholes are drilled downwards at both bottom corners. A brushing operation is performed at the bottom of these large-diameter isolation boreholes to form pressure relief pits. Water is injected into the large-diameter isolation boreholes, and then waste gangue is filled into them. Grouting boreholes are drilled into the interior of the roadway floor area at both bottom corners, forming a grouting network. The large-diameter interruption boreholes and trumpet-shaped pressure relief holes used in this invention can significantly block the transmission of stress and load on the roof, reducing the stress on the roadway floor. The grouting mesh can increase the strength of the weak roadway floor without damaging it, thus improving the stability of the roadway floor. Moreover, the construction is simple, and the required equipment and materials are all commonly used on-site. The process is simple, the cost is low, and the effect is obvious. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a side view of the overall structure of the present invention; Figure 3This is a top view of the overall structure of the present invention; Figure 4 This is a schematic diagram of the state after grouting according to the present invention; Among them: 1. Roadway area; 2. Large-diameter partition borehole; 3. Soft floor or bottom coal floor; 4. Hard rock strata; 5. Pressure relief cavity; 6. Gangue; 7. Grouting borehole; 8. Rhomboid grouting mesh unit; 9. Water injection softening area; 10. Grout diffusion area. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0021] Reference Figures 1-4 This invention provides a method for actively preventing floor heave in coal mine roadways using a cross-grouting mesh, comprising the following steps: Based on stress measurement and roadway surrounding rock deformation monitoring data, roadway areas 1 with weak floor or bottom coal 3 were identified and delineated; At the two bottom corners of the tunnel area 1, multiple large-diameter partition holes 2 are drilled diagonally downwards. A brushing and enlarging operation is performed at the bottom of the large-diameter partition borehole 2 to form a pressure relief cavity 5 at the bottom of the large-diameter partition borehole 2. Water is injected into the large-diameter partition borehole 2 and the pressure relief cavity 5. After water injection, waste gangue 6 is filled into the large-diameter partition borehole 2 and the pressure relief cavity 5. At the bottom of tunnel area 1, multiple grouting holes 7 are drilled obliquely into the tunnel floor and grout is injected, forming a grouting network.

[0022] In one embodiment of the present invention, in the development roadway, preparation roadway, and mining roadway, the roadway floor area and damage range with weak floor plate and retained coal floor plate are determined and demarcated according to methods such as stress measurement and roadway surrounding rock deformation monitoring data; within the demarcated damage range or in the roadway area 1 prone to floor heave, large-diameter isolation boreholes 2 are drilled downwards from two bottom corners. The depth of the large-diameter isolation boreholes 2 must exceed the weak floor plate or retained coal floor plate 3, reaching the hard rock layer 4. A brushing operation is performed at the bottom of the large-diameter isolation boreholes 2 to increase the fracture area at the bottom of the large-diameter isolation boreholes 2, so that... The large-diameter isolation borehole 2 is a funnel-shaped pressure relief cavity 5 with a thicker bottom and a thinner top, which increases the fractured area of ​​the hard rock layer 4 at the bottom and further blocks the transmission of high stress to the hard rock layer. Water is injected into the large-diameter isolation borehole 2 to increase the area of ​​the water-softened area 9 in the pressure relief cavity 5. After water injection, waste gangue 6 is filled into the large-diameter isolation borehole 2. The particle size of gangue 6 can be processed according to the site conditions to ensure that gangue 6 can fill the large-diameter isolation borehole 2. Grouting boreholes 7 are drilled into the bottom plate of the tunnel area 1 at both bottom feet. Multiple grouting boreholes 7 form a grouting network. The large-diameter isolation borehole 2 and the trumpet-shaped pressure relief cavity 5 used in this invention can significantly block the transmission of stress and load on the roof plate, reducing the stress on the roadway floor. The grouting mesh can increase the strength of the weak roadway floor without damaging it, improve the stability of the roadway floor, and is simple to construct. The required equipment and materials are all commonly used on site. The process is simple, the cost is low, and the effect is obvious.

[0023] As an optional implementation, the diameter of the large-diameter partition hole 2 is 100mm-110mm, and the distance between two adjacent large-diameter partition holes 2 is 1300mm-1700mm.

[0024] In one embodiment of the present invention, the borehole diameter is controlled at 100-110mm and the spacing is controlled at 1300-1700mm. This ensures sufficient isolation space and pressure relief range, effectively blocking the transmission of deep stress in the base plate, while avoiding construction waste caused by excessively dense drilling, thus achieving a balance between prevention and control effects and project costs.

[0025] As an optional implementation, the axis of the large-diameter partition borehole 2 is at an angle of 5°-10° with the vertical direction, and the deflection direction points to the outside of the tunnel area 1.

[0026] In one embodiment of the present invention, the borehole is inclined outward, which can actively guide the concentrated stress of the floor plate to the stable rock mass outside the roadway outline, reduce the direct effect of stress on the roadway floor plate, and at the same time provide a more stable support for subsequent filling of waste gangue, thereby improving the durability of pressure relief.

[0027] As an optional implementation, the diameter of the grouting borehole 7 is 50mm-73mm.

[0028] In one embodiment of the present invention, small-diameter grouting holes of 50-73mm are used, which not only meet the requirements for grout delivery and diffusion, but also reduce secondary disturbance to the bottom rock strata. The drilling construction is fast and low-cost, and it is easy to form a dense grouting network.

[0029] As an optional implementation, the projected length of the grouting borehole 7 is 1 / 2 of the width of the tunnel cross-section.

[0030] In one embodiment of the present invention, the length of the grouting borehole 7 is determined according to the width of the roadway cross-section, ensuring that the projected length of the grouting borehole 7 reaches 1 / 2 of the width of the roadway cross-section.

[0031] As an optional implementation, four adjacent grouting holes 7 form a rhombus grouting mesh unit 8, and multiple rhombus grouting mesh units 8 form a grouting mesh.

[0032] In one embodiment of the present invention, the rhomboid grouting mesh unit 8 causes the grout to cross-link and diffuse in the base plate in a mesh-like manner, forming an integral reinforcement layer, which significantly improves the bending stiffness of the base plate, effectively suppresses the deformation of the base plate, and the unitized hole layout facilitates standardized construction and quality control.

[0033] As an optional implementation, the four grouting holes 7 in the diamond grouting mesh unit 8 are divided into two groups and symmetrically arranged at the bottom plate position of the roadway area 1. The distance between the two grouting holes 7 in the same group is 500mm, and the distance between each group of grouting holes 7 and the corresponding side coal wall of the roadway area 1 is 500mm.

[0034] In one embodiment of the present invention, symmetrical holes are arranged and kept 500mm away from the coal wall to accurately lock the two bottom corners and the key area of ​​the middle prone to bottom heave, so that the stress field of grouting reinforcement matches the stress field of the surrounding rock of the roadway, avoids eccentric loading, and achieves uniform reinforcement.

[0035] As an optional implementation, the grouting holes 7 are arranged around the large-diameter partition holes 2, and the two grouting holes 7 in the same group and the adjacent large-diameter partition holes 2 are distributed in the plane as equilateral triangle vertices.

[0036] In one embodiment of the present invention, the equilateral triangle layout enables the partition hole and the grouting hole 7 to form a stable mechanical structure in space. The pressure relief zone and the reinforcement zone are interlocked, which not only prevents stress from bypassing the partition layer, but also fixes the filling gangue 6 with the grouting body, thus synergistically improving the overall stability of the base plate.

[0037] As an optional implementation, the grouting borehole 7 has an angle of 20°-40° with the roadway floor plane in the vertical direction, and an angle of 20°-35° with the line connecting the center of the roadway cross section in the horizontal direction.

[0038] In one embodiment of the present invention, double-angle inclined grouting is adopted, which allows the drilling trajectory to penetrate more weak layers. The grout is fully diffused in three-dimensional space to form a three-dimensional intersecting grouting curtain, which significantly improves the integrity and shear resistance of the reinforcement layer. Specifically, concrete grout is injected into the grouting borehole 7 to ensure that the weak bottom plate or the bottom coal bottom plate 3 is fused with the concrete grout, and to reinforce the grouting area and the grout diffusion area 10, thereby improving the strength and bearing capacity of the weak bottom plate.

[0039] As an optional implementation, the openings of the large-diameter partition borehole 2 and the grouting borehole 7 are sealed.

[0040] In one embodiment of the present invention, the top of the large-diameter partition borehole 2 and the grouting borehole 7 is sealed to ensure the integrity of the bottom plate of the tunnel area 1 and avoid affecting the normal use of the tunnel area 1.

[0041] This invention provides a method for actively preventing floor heave in coal mine roadways using a cross-grouting mesh, applicable to areas with weak or residual coal flooring that are prone to floor heave damage. In use, firstly, the load on the top coal and rock mass of roadway area 1 is composed of ground stress, static load from roadway excavation, and dynamic load from face mining and roof fracture. The stress and load are transmitted downwards through the coal mass on both sides of the roadway. When transmitted to the floor of roadway area 1, they are blocked by the large-diameter isolation borehole 2, reducing the transmission of high stress to the roadway floor. Secondly, the bottom of the large-diameter isolation borehole 2 forms a funnel-shaped pressure relief cavity 5, which can further block and consume the high load transmitted from the roof. Water injection into the large-diameter isolation borehole 2 accelerates the softening of the hard rock layer 4, reducing the amount of high stress and energy stored in the hard rock layer 4, and reducing the stress on the floor of roadway area 1. Gangue 6 is filled into the large-diameter partition borehole 2. The crushed gangue 6 can maintain the integrity of the large-diameter partition borehole 2, improve the blocking effect on vertical loads, and the space gaps between the gangue 6 can further absorb energy and reduce stress value. Finally, boreholes are drilled in the weak floor or the bottom coal floor 3 to open multiple grouting boreholes 7. The grouting boreholes 7 are drilled and grouted according to the above method. According to the distribution pattern of the grouting boreholes 7, a rhomboid grouting mesh unit 8 can be formed. The four grouting boreholes 7 of each rhomboid grouting mesh unit 8 together form a rhomboid three-dimensional area. The grout diffusion range can provide all-round three-dimensional reinforcement of the floor of the roadway area 1, ensuring the flatness and stability of the roadway floor.

[0042] This invention can prevent floor heave damage in roadway area 1. The large-diameter isolation boreholes 2 and the trumpet-shaped pressure relief holes 5 can significantly block the transmission of roof stress and load, reducing the stress on the floor of roadway area 1. The diamond-shaped grouting mesh unit 8 can increase the strength of the weak floor or the bottom coal floor 3 without damaging the floor of roadway area 1, thereby improving the stability of the floor of roadway area 1. Moreover, this method is simple to construct, and the required equipment and materials are all commonly used on site. The process is simple, the cost is low, and the effect is obvious.

[0043] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0044] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for actively preventing floor heave in coal mine roadways using cross-type grouting mesh, characterized in that, Includes the following steps: Based on stress measurement and roadway surrounding rock deformation monitoring data, roadway areas with weak floor or bottom coal floor (3) were identified and delineated (1). At the two bottom corners of the tunnel area (1), multiple large-diameter partition holes (2) are drilled obliquely downwards respectively. A brushing and enlarging operation is performed at the bottom of the large-diameter partition borehole (2) to form a pressure relief cavity (5) at the bottom of the large-diameter partition borehole (2). Water is injected into the large-diameter partition borehole (2) and the pressure relief cavity (5), and then waste gangue (6) is filled into the large-diameter partition borehole (2) and the pressure relief cavity (5). At the bottom of the roadway area (1), multiple grouting holes (7) are drilled obliquely into the roadway floor and grout is injected. The multiple grouting holes (7) form a grouting network.

2. The method for actively preventing floor heave in coal mine roadways using cross-type grouting mesh according to claim 1, characterized in that: The diameter of the large-diameter partition hole (2) is 100mm-110mm, and the distance between two adjacent large-diameter partition holes (2) is 1300mm-1700mm.

3. The method for actively preventing floor heave in coal mine roadways using cross-type grouting mesh according to claim 1, characterized in that: The axis of the large-diameter partition borehole (2) is at an angle of 5°-10° with the vertical direction, and the deflection direction points to the outside of the tunnel area (1).

4. The method for actively preventing floor heave in coal mine roadways using cross-type grouting mesh according to claim 1, characterized in that: The diameter of the grouting borehole (7) is 50mm-73mm.

5. The method for actively preventing floor heave in coal mine roadways using cross-type grouting mesh according to claim 1, characterized in that: The projected length of the grouting borehole (7) is 1 / 2 of the width of the roadway cross section.

6. The method for actively preventing floor heave in coal mine roadways using cross-type grouting mesh according to claim 1, characterized in that: Each set of four adjacent grouting holes (7) forms a rhombus grouting mesh unit (8), and multiple rhombus grouting mesh units (8) form the grouting mesh.

7. The method for actively preventing floor heave in coal mine roadways using cross-type grouting mesh according to claim 6, characterized in that: The four grouting holes (7) in the diamond-shaped grouting mesh unit (8) are divided into two groups and symmetrically arranged at the bottom plate position of the roadway area (1). The distance between the two grouting holes (7) in the same group is 500mm, and the distance between each group of grouting holes (7) and the corresponding side coal wall of the roadway area (1) is 500mm.

8. The method for actively preventing floor heave in coal mine roadways using cross-type grouting mesh according to claim 1, characterized in that: The grouting holes (7) are arranged around the large-diameter partition holes (2), and the two grouting holes (7) in the same group and the adjacent large-diameter partition holes (2) are distributed in the plane as the vertices of an equilateral triangle.

9. The method for actively preventing floor heave in coal mine roadways using cross-type grouting mesh according to claim 1, characterized in that: The grouting borehole (7) has an angle of 20°-40° with the roadway floor plane in the vertical direction, and an angle of 20°-35° with the line connecting the center of the roadway cross section in the horizontal direction.

10. The method for actively preventing floor heave in coal mine roadways using cross-type grouting mesh according to claim 1, characterized in that: The openings of the large-diameter partition borehole (2) and the grouting borehole (7) are sealed.

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