A construction method for grouting control of a roof of a gob-side top coal caving mining stope

Abstract

The application provides a construction method for grouting control of a roof of a gob-side top-coal-cutting left lane, and the construction method comprises the following steps: step 1, cutting a seam on the roof of the left lane from the roadway; step 2, drilling a lane-drilling hole in the surrounding rock in the roadway obliquely upwards, and continuously carrying out gas drainage through the lane-drilling hole; the lane-drilling hole comprises a plurality of low-position lane-drilling holes and a plurality of high-position lane-drilling holes; step 3, after the working face is mined, stopping the gas drainage in the roadway drilling hole, carrying out filling grouting through the low-position lane-drilling hole, and carrying out permeation and splitting grouting through the high-position lane-drilling hole; step 4, after the working face is mined, the roof of the goaf starts to collapse, at this time, a surface drilling hole is drilled from the surface downwards and grouting is carried out; the surface drilling hole comprises a surface high-position drilling hole and a surface low-position drilling hole. The construction method can effectively control the deformation of the overlying strata of the goaf in the case that the top cutting effect is not ideal.

Description

Technical Field

[0001] This invention belongs to the technical field of roof cutting and pressure relief roadway retention, specifically relating to a construction method for grouting control of the roof of a roadway retention mining area. Background Technology

[0002] Many coal mines in my country have coal seams under the "three underground" conditions. The mining of these coal seams has strict requirements on the amount of surface subsidence. If the roof cutting effect in the roof cutting and pressure relief roadway is not ideal, that is, the roof of the goaf does not collapse sufficiently and the collapsed gangue does not completely fill the goaf, the roof of the goaf will deform under the pressure of the overlying rock, forming "two zones, one area, and two interfaces" above the goaf. This will cause the surface subsidence to exceed the allowable range, which can easily cause damage to surface buildings and railways, and lead to underground water inrush accidents.

[0003] The technology of cutting the roof and leaving the roadway along the goaf involves pre-splitting the roof to cut off the stress transmission of the roof, thereby preserving the roadway along the goaf for the next working face. This technology can improve the roof collapse effect in the goaf, and the crushing and swelling properties of the collapsed gangue can make the gangue fill the goaf more fully, thereby reducing surface subsidence. However, in actual construction, the roof cutting effect cannot be guaranteed. How to control the roof of the goaf cutting and roadway leaving mining area when the roof cutting effect is not ideal is still an unsolved problem.

[0004] Therefore, there is a need to provide an improved technical solution that addresses the shortcomings of the existing technology. Summary of the Invention

[0005] The purpose of this invention is to provide a construction method for grouting control of the roof of the goaf-cutting and roadway-retaining mining area, so as to at least solve the above-mentioned problems existing in the prior art.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A construction method for grouting control of the roof of a goaf-cutting and roadway-retaining mining area, wherein the rock strata are arranged in the following order from bottom to top above the coal seam: rock strata 1, rock strata 2, rock strata 3, rock strata 4, rock strata 5, rock strata 6 and rock strata 7.

[0008] The construction method includes the following steps:

[0009] Step 1: Excavate two roadways in the coal seam. The middle section of the two roadways forms a working face. Cut a groove in the roof of the roadway from inside the roadway.

[0010] Step 2: After the surrounding rock that has been cut has stabilized, drill boreholes in the surrounding rock at an angle upward in the tunnel and continuously drain gas through the boreholes.

[0011] The boreholes in the tunnel include multiple low-level boreholes and multiple high-level boreholes in the tunnel, wherein the depth of the high-level boreholes in the tunnel is greater than the depth of the low-level boreholes in the tunnel.

[0012] Step 3: After the working face has been mined, stop the gas drainage from the boreholes in the roadway, and carry out filling grouting through the low-level boreholes in the roadway, and carry out infiltration and fracturing grouting through the high-level boreholes in the roadway; wherein, the grouting pressure of infiltration and fracturing grouting is higher than that of filling grouting.

[0013] Step 4: After the working face has been mined, the roof of the goaf begins to collapse. At this time, surface boreholes are drilled from the surface downwards, and grout is injected into the surrounding rock through the surface boreholes.

[0014] The surface boreholes include high-level surface boreholes and low-level surface boreholes, with the depth of the low-level boreholes being greater than the depth of the high-level surface boreholes.

[0015] The grouting control method for the roof of the goaf-cutting and roadway-retaining mining area, as described above, preferably involves the following: after the working face is mined, rock stratum 1 collapses and forms broken gangue in the goaf; the termination position of the low-level borehole in the roadway is the junction of rock stratum 1 and rock stratum 2, and the termination positions of multiple low-level boreholes in the roadway are evenly distributed in the width direction of the coal seam.

[0016] In the above-described method for grouting control of the roof of the goaf-cutting and roadway-retaining mining area, preferably, after the collapse of rock stratum one, rock stratum two and rock stratum three above rock stratum one form a fracture zone, and the termination positions of multiple high-level boreholes in the roadway are evenly distributed within the fracture zone formed by rock stratum two and rock stratum three.

[0017] In the above-described method for grouting control of the roof of the goaf-cutting and roadway-retaining mining area, preferably, multiple boreholes in the roadway are drilled within a single roadway.

[0018] The grouting control method for the construction of the roof of the goaf-cutting and roadway-retaining mining area, as described above, preferably forms a curved subsidence zone in the rock strata four and five above the rock strata three, and the termination position of multiple low-level surface boreholes is located inside the curved subsidence zone.

[0019] The grouting control method for the construction of the roof of the goaf-cutting and roadway-retaining mining area, as described above, preferably involves the formation of a separation zone between rock stratum five and rock stratum six, with the termination positions of multiple high-level surface boreholes located within the separation zone.

[0020] In the above-described method for grouting control of the roof of the goaf-cutting and roadway-retaining mining area, preferably, the grouting fluid used for grouting in the roadway boreholes is malissa.

[0021] The construction method for grouting control of the roof of the goaf-cutting and roadway-retaining mining area as described above, preferably, uses malissa as the grouting fluid when grouting in the low-level surface boreholes;

[0022] The grouting fluid used for grouting in the high-level surface boreholes is cement or mud.

[0023] The grouting control method for the construction of the roof of the goaf-cutting and roadway retention mining area, as described above, preferably involves, in step 1, the cut penetrating the rock strata above the coal seam, and the cut inclined toward the central axis of the two roadways, so as to separate the roof above the coal seam from the roof above the roadway.

[0024] In the above-described method for grouting control of the roof of the goaf in the goaf-cutting and roadway-keeping mining area, preferably, the height of the goaf is proportional to the number of vertical rows of boreholes in the roadway, the width of the goaf is proportional to the number of horizontal rows of boreholes in the roadway, and the width of the goaf is proportional to the number of surface boreholes.

[0025] Beneficial effects:

[0026] This construction method involves setting up low-level and high-level boreholes within the roadway, combined with grouting in the surface boreholes. This allows for faster filling of the surrounding rock above the goaf, reducing surface subsidence caused by insufficient roof cutting and minimizing potential gas outbursts before the working face is mined. It is an economical and relatively simple method for controlling the roof of the mining area. Attached Figure Description

[0027] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. Wherein:

[0028] Figure 1 This is a schematic diagram of the initial positions of various rock layers according to an embodiment of the present invention;

[0029] Figure 2 This is a schematic diagram of the slit arrangement according to an embodiment of the present invention;

[0030] Figure 3 This is a schematic diagram of drilling inside a tunnel according to an embodiment of the present invention;

[0031] Figure 4 This is a view of the deformation of the overlying strata in the goaf and the boreholes in the tunnel and the surface boreholes, according to an embodiment of the present invention.

[0032] In the diagram: 1. Rock stratum 7, 2. Rock stratum 6, 3. Rock stratum 5, 4. Rock stratum 4, 5. Rock stratum 3, 6. Rock stratum 2, 7. Rock stratum 1, 8. Coal seam, 9. Cut joint, 10. Roadway with retained sections, 11. Roadway without retained sections, 12. High-level borehole 1 in the roadway, 13. High-level borehole 2 in the roadway, 14. Low-level borehole 1 in the roadway, 15. Low-level borehole 2 in the roadway, 16. Low-level borehole 3 in the roadway, 17. High-level borehole on the surface, 18. Low-level borehole on the surface, 19. Delamination zone, 20. Interface 2, 21. Interface 1. Detailed Implementation

[0033] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.

[0034] In the description of this invention, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," and "bottom," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and do not require the invention to be constructed and operated in a specific orientation; therefore, they should not be construed as limitations on the invention. The terms "connected" and "linked" used in this invention should be interpreted broadly. For example, they can refer to a fixed connection or a detachable connection; they can refer to a direct connection or an indirect connection through intermediate components. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0035] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other.

[0036] According to specific embodiments of the present invention, such as Figure 1-4 As shown, the present invention provides a construction method for grouting control of the roof of the goaf-cutting and roadway retention mining area, which includes rock strata 1 7, rock strata 2 6, rock strata 3 5, rock strata 4 4, rock strata 5 3, rock strata 6 2 and rock strata 7 1 in sequence from bottom to top above coal seam 8.

[0037] The construction method includes the following steps:

[0038] Step 1: Excavate two roadways in coal seam 8. The middle section of the two roadways forms a working face. Cut a groove 9 in the roof of the roadway 10 from inside the roadway.

[0039] Step 2: After the surrounding rock deformation stabilizes after the cut 9, drill boreholes obliquely upwards in the surrounding rock within the tunnel and continuously drain gas through the boreholes.

[0040] The drilling within the tunnel includes multiple low-level boreholes and multiple high-level boreholes, with the depth of the high-level boreholes being greater than that of the low-level boreholes.

[0041] Step 3: After the working face has been mined, stop the gas drainage from the boreholes in the roadway, and carry out filling grouting through the low-level boreholes in the roadway, and carry out infiltration and fracturing grouting through the high-level boreholes in the roadway; wherein, the grouting pressure of infiltration and fracturing grouting is higher than that of filling grouting.

[0042] Step 4: After the working face has been mined, the roof of the goaf begins to collapse. At this time, surface boreholes are drilled from the ground surface downwards, and grout is injected into the surrounding rock through the surface boreholes.

[0043] The surface boreholes include a high-level surface borehole 17 and a low-level surface borehole 18, with the depth of the low-level borehole being greater than the depth of the high-level surface borehole 17.

[0044] In this construction method, low-level and high-level boreholes are set up in the roadway. The boreholes in the roadway not only enable continuous gas drainage before the mining of coal seam 8 is completed, thus ensuring the safety of coal seam 8 mining; after the mining of coal seam 8 is completed, the gas drainage in the boreholes in the roadway is quickly stopped, and grouting is carried out in the boreholes in the roadway. The grout is quick-drying cement, which facilitates the rapid solidification of the grout. At the same time, combined with grouting in the surface boreholes, the surrounding rock above the goaf can be filled more quickly, avoiding the subsidence of the surface of the goaf.

[0045] After the working face was mined, rock stratum 7 collapsed and formed a goaf with broken gangue; the termination position of the low-level borehole in the roadway was at the junction of rock stratum 7 and rock stratum 26, and the termination positions of multiple low-level boreholes in the roadway were evenly distributed in the width direction of coal seam 8.

[0046] In one embodiment of this application, rock stratum 7 is the immediate roof of the goaf, and rock stratum 6 is the basic roof of the goaf. That is, the termination position of the low-level borehole in the roadway is located between the immediate roof and the basic roof of the goaf. After the working face is mined, the overlying rock strata of the goaf gradually deform, and the rock strata form broken gangue, fracture zone, and bending zone from bottom to top. There is an interface 21 between the broken gangue and the fracture zone, and an interface 20 between the fracture zone and the bending zone. A delamination zone 19 is formed between the bending zone and the upper rock strata with smaller deformation. The above-mentioned deformation of the overlying rock constitutes "two zones, one zone, and two interfaces".

[0047] The low-level boreholes in the roadway extend into the interface 21 between the broken gangue and the fracture zone in the goaf. Grouting is then carried out through the low-level boreholes in the roadway to form a closed isolation surface in the interface 21, thus separating the broken gangue and the fracture zone in the goaf. This prevents the fracture zone from developing further after the working face is mined and ensures that the fracture zone is well supported.

[0048] After the collapse of rock stratum 7, rock stratum 26 and rock stratum 35 above rock stratum 7 formed a fracture zone. The termination positions of multiple high-level boreholes in the tunnel were evenly distributed within the fracture zone formed by rock stratum 26 and rock stratum 35.

[0049] In one embodiment of this application, grouting is performed through high-level borehole drilling within the tunnel. This grouting fluid disperses within the fracture zone formed by rock strata 2 (6) and strata 3 (5), sealing the regenerated fractures within the fracture zone and bonding the fracture zone into a unified whole. This enhances the supporting force of the fracture zone and gives it better stability and bearing capacity. Furthermore, after grouting through borehole drilling within the tunnel, the goaf and overlying strata are separated by the grout, thereby preventing gas from entering the tunnel 10 from the rock strata.

[0050] Multiple boreholes are drilled within a single roadway. In one embodiment of the application, the working face is divided into a retaining roadway 10 and a non-retaining roadway 11 on either side. Multiple low-level and high-level boreholes are drilled within the retaining roadway 10, allowing grouting equipment to be installed in only one roadway to complete grouting operations for all boreholes. This saves grouting costs and facilitates grouting operations. The low-level boreholes include Low-level Borehole 14, Low-level Borehole 25, and Low-level Borehole 36; all three extend into the interface 21. The high-level boreholes include High-level Borehole 12 and High-level Borehole 23, with High-level Borehole 12 extending into rock stratum 26 and High-level Borehole 23 extending into rock stratum 35.

[0051] In other embodiments, roadways are set up on both sides of the working face. In this case, boreholes can be drilled from the roadways on both sides of the working face, so that the boreholes can be drilled nearby in the roadways on both sides of the working face. This helps to reduce the length of the roadway boreholes and thus reduce the grouting transmission distance.

[0052] A tortuous subsidence zone is formed between rock layers 4 and 5 above rock layer 35, and the termination points of multiple low-level surface boreholes 18 are located inside the tortuous subsidence zone. In one embodiment of this application, grout is injected into the tortuous subsidence zone through surface boreholes to fill the fine cracks within the tortuous subsidence zone, thereby inhibiting the development of fine cracks within the tortuous subsidence zone composed of rock layers 4 and 53, and thus reducing the tortuous subsidence of rock layers 4 and 53.

[0053] A separation zone 19 is formed between rock stratum 53 and rock stratum 62, and the termination points of multiple high-level surface boreholes 17 are located inside the separation zone 19.

[0054] In one embodiment of this application, grouting is performed in the delamination zone 19 through a high-level surface borehole 17, wherein the surface borehole is subjected to high-pressure grouting; so that the delamination zone 19 is filled with grouting fluid, thereby eliminating the space for downward displacement of the delamination zone 19 as much as possible, which also avoids the possibility of deformation of the delamination zone 19 as much as possible.

[0055] The grouting fluid used for grouting in the tunnel borehole is malissa. In one embodiment of this application, the low-level grouting fluid has a certain degree of adhesion and strength, and needs to share the pressure of the overlying strata with the goaf gangue; malissa, also known as polyurethane resin material, has good adhesion and high strength, making it easier to bond and fill the broken gangue and fracture zone in the goaf, and ensuring that the broken gangue and fracture zone in the goaf have good overall structural strength after grouting.

[0056] The grouting fluid used for grouting in the low-level surface borehole 18 is malathion; the grouting fluid used for grouting in the high-level surface borehole 17 is cement or mud.

[0057] In one embodiment of this application, the low-level surface borehole 18 uses malathion as the grouting fluid, which can ensure that the bending and subsidence zone is well bonded and filled, thereby further controlling the bending and subsidence of the bending and subsidence zone; while the high-level surface borehole 17 uses cement or mud, which is injected into the abscission zone 19, and mainly plays a filling role in the abscission zone 19, thereby controlling the upper rock strata from sinking significantly.

[0058] In step 1, the cut 9 penetrates the rock stratum 7 above the coal seam 8, and the cut 9 is inclined toward the central axis of the two roadways so that the roof above the coal seam 8 is separated from the roof above the roadway.

[0059] In one embodiment of this application, two upward-sloping cuts 9 are provided in both roadways, and both cuts 9 are inclined toward the central axis of the two roadways. Specifically, the angle between the cuts 9 and the horizontal plane is less than 90°; and the cuts penetrate the rock stratum 7. This makes the two cuts 9 form a roof with a trapezoidal cross-section in the rock stratum 7. After the coal seam 8 is mined, the trapezoidal roof is more likely to collapse, thus ensuring a better collapse effect.

[0060] The height of the goaf is directly proportional to the number of vertical rows of boreholes in the roadway, the width of the goaf is directly proportional to the number of horizontal rows of boreholes in the roadway, and the width of the goaf is directly proportional to the number of surface boreholes.

[0061] In one embodiment of this application, when the height of the goaf is large, the number of vertical rows of grouting pipes is increased appropriately, and when the length of the goaf is large, the number of horizontal rows is increased. That is, the higher the height of the goaf, the more vertically arranged the boreholes in the roadway; the wider the goaf, the more horizontally arranged the boreholes in the roadway. At the same time, the wider the goaf, the more horizontally arranged the surface boreholes, and the boreholes are mainly arranged towards the pores.

[0062] In summary, after the roof of the goaf collapses along the cut joint in the working face, this application proposes to control the roof of the goaf-cutting and roadway-retaining mining area by conducting multi-dimensional grouting operations through drilling in the roadway and on the surface. This can effectively control the deformation of the overlying strata in the goaf when the roof cutting effect is not ideal, and solve the problem of surface subsidence.

[0063] It is understood that the above description is merely exemplary and the embodiments of this application do not limit the scope of the application.

[0064] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention shall be within the scope of protection of the pending claims of the present invention.

Claims

1. A construction method for grouting control of the roof of a goaf-cutting and retaining roadway, characterized in that, Above the coal seam, from bottom to top, there are rock strata one, rock strata two, rock strata three, rock strata four, rock strata five, rock strata six, and rock strata seven; The construction method includes the following steps: Step 1: Excavate two roadways in the coal seam. The coal body in the middle of the two roadways forms a working face section. Cut a groove in the roof of the roadway from inside the roadway. Step 2: After the surrounding rock that has been cut has stabilized, drill boreholes in the surrounding rock at an angle upward in the tunnel and continuously drain gas through the boreholes. The boreholes in the tunnel include multiple low-level boreholes and multiple high-level boreholes in the tunnel, wherein the depth of the high-level boreholes in the tunnel is greater than the depth of the low-level boreholes in the tunnel. Step 3: After the working face has been mined, stop the gas drainage from the boreholes in the roadway, and carry out filling grouting through the low-level boreholes in the roadway, and carry out infiltration and fracturing grouting through the high-level boreholes in the roadway; wherein, the grouting pressure of infiltration and fracturing grouting is higher than that of filling grouting. Step 4: After the working face has been mined, the roof of the goaf begins to collapse. At this time, surface boreholes are drilled from the surface downwards, and grout is injected into the surrounding rock through the surface boreholes. The surface boreholes include high-level surface boreholes and low-level surface boreholes, with the depth of the low-level surface boreholes being greater than the depth of the high-level surface boreholes.

2. The construction method for grouting control of the roof slab in the goaf-cutting and roadway-retaining mining area according to claim 1, characterized in that, After the working face is mined, rock stratum 1 collapses and forms a goaf with broken gangue; the termination position of the low-level borehole in the roadway is the junction of rock stratum 1 and rock stratum 2, and the termination positions of multiple low-level boreholes in the roadway are evenly distributed in the width direction of the coal seam.

3. The construction method for grouting control of the roof of the goaf-cutting and roadway-retaining mining area according to claim 2, characterized in that, After the collapse of rock stratum 1, rock stratum 2 and rock stratum 3 above rock stratum 1 formed a fracture zone, and the termination positions of multiple high-level boreholes in the tunnel were evenly distributed within the fracture zone formed by rock stratum 2 and rock stratum 3.

4. The construction method for grouting control of the roof slab in the goaf-cutting and roadway-retaining mining area according to claim 3, characterized in that, All of the aforementioned boreholes were drilled within a single tunnel.

5. The construction method for grouting control of the roof slab in the goaf-cutting and roadway-retaining mining area according to claim 3, characterized in that, The rock layers four and five above rock layer three form a curved subsidence zone, and the termination points of multiple low-level surface boreholes are located inside the curved subsidence zone.

6. The construction method for grouting control of the roof of the goaf-cutting and roadway-retaining mining area according to claim 5, characterized in that, A delamination zone is formed between rock strata five and six, and the termination points of multiple high-level surface boreholes are located inside the delamination zone.

7. The construction method for grouting control of the roof of the goaf-cutting and retaining roadway according to any one of claims 1-6, characterized in that, The grouting fluid used for grouting in the boreholes within the alley is malissa.

8. The construction method for grouting control of the roof of the goaf-cutting and roadway-retaining mining area according to claim 7, characterized in that, The grouting fluid used during grouting of the low-level surface boreholes is malissa; The grouting fluid used for grouting in the high-level surface boreholes is cement or mud.

9. The construction method for grouting control of the roof of the goaf-cutting and retaining roadway according to any one of claims 1-6, characterized in that, In step 1, the cut penetrates the rock stratum above the coal seam, and the cut is inclined toward the central axis of the two roadways so as to separate the roof above the coal seam from the roof above the roadway.

10. The construction method for grouting control of the roof of the goaf-cutting and retaining roadway according to any one of claims 1-6, characterized in that, The height of the goaf is directly proportional to the number of vertical rows of boreholes in the roadway, the width of the goaf is directly proportional to the number of horizontal rows of boreholes in the roadway, and the width of the goaf is directly proportional to the number of surface boreholes.

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