A method for hierarchical differential grouting filling in overlying strata

Abstract

The present invention discloses a method for grouting and filling in a stepped and differentiated manner in different zones of overlying strata, which comprises the following steps: taking cores after construction for mechanical tests to determine the horizons of the main key strata; determining the plane positions of grouting holes, and conducting indoor simulation tests according to the plane positions of the grouting holes to determine the mixing ratio of the filling materials for grouting in a stepped and differentiated manner in different zones of overlying strata and the standing time T after grouting; grouting through a grouting pump and the first-layer grouting holes according to the material mixing ratio in step two; after the standing time T is completed in step three, arranging the second-layer grouting holes, and conducting second-layer grouting through the grouting pump and the second-layer grouting holes, and ending the grouting and filling operation when saturated compaction bodies are formed by the precipitation of the slurry in the caving zone. The present invention can make a single long drill hole serve multiple purposes, conduct stepped and layered grouting, achieve better subsidence reduction effect by grouting, make the slurry conveying pipeline simpler, reduce the filling cost, realize parallel operation between underground mining and ground grouting and filling without interference with each other, and promote the safe and green mining of coal.

Description

Technical Field

[0001] The present invention relates to the technical field of green filling mining subsidence control in the coal industry, and particularly to a method for grouting and filling with different levels in different zones of overlying strata. Background Art

[0002] Ecological environment problems such as surface subsidence, groundwater system damage, and gangue discharge caused by large-scale coal resource mining have become increasingly prominent. In recent years, the technology of reducing subsidence by grouting in the separated strata of overlying strata has become one of the effective technical ways to solve the above problems due to its low cost, high coal recovery rate and production efficiency, and suitability for high-yield production.

[0003] Traditional grouting in the separated strata of overlying strata makes full use of the separated strata space after coal seam mining, injects the filling material into the separated strata area through ground drilling, and after the slurry precipitates, the water goes away and the ash remains, forming a bearing body of "separated strata filling body - coal pillar - key stratum" to ensure that the upper strata and the ground do not collapse, realizing parallel operation of underground mining and ground grouting and filling without interference. However, for the treatment of the caving zone and fracture zone in traditional separated strata grouting, usually, the separated strata grouting is carried out after the caving zone is naturally caved and compacted, or while drilling and grouting in the separated strata area, high-level boreholes are drilled into the caving zone and fracture zone, resulting in a large time span of separated strata grouting, complex filling technology, and too long slurry conveying pipeline, resulting in high filling cost. Therefore, there is an urgent need for a method for grouting and filling with different levels in different zones of overlying strata to solve the above problems. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for grouting and filling with different levels in different zones of overlying strata to solve the problems existing in the above-mentioned prior art, which can realize grouting in hierarchical layers, has a better effect of reducing subsidence by grouting, has a simpler slurry conveying pipeline, reduces the filling cost, realizes parallel operation of underground mining and ground grouting and filling, and ensures the safe and green mining of coal.

[0005] To achieve the above purpose, the present invention provides the following solution: The present invention provides a method for grouting and filling with different levels in different zones of overlying strata, including the following steps:

[0006] Step 1: Determine the position of the main key stratum: After construction, take cores for mechanical tests to determine the position of the main key stratum. The distance from the main key stratum to the ground is H1, and H1 is the length of the first grouting borehole.

[0007] Step 2: Preparation before grouting: Determine the plane position of the grouting holes, and conduct indoor simulation tests according to the plane position of the grouting holes to determine the mixing ratio of the filling material for grouting with different levels in different zones of overlying strata and the static time T after grouting.

[0008] Step 3: Directional drilling and grouting: Grout according to the material mixing ratio in Step 2 through the grouting pump and the first-layer grouting borehole.

[0009] Step 4: Grouting of the second layer: After the completion of Step 3, let it stand for a time T. Set the grouting holes for the second layer, and conduct the grouting of the second layer through the grouting pump and the grouting holes for the second layer. The grouting filling operation ends when the slurry forms a saturated compaction body in the caving zone.

[0010] Preferably, after the drilling construction in Step 1, take cores for mechanical tests, and determine the main key stratum layer and the separated zone according to the mud loss situation of the drilling holes and the core situation.

[0011] Preferably, in Step 2, construct the grouting holes for the first layer before the caving in the goaf. The plane position of the grouting holes is located in the separated zone. There are two grouting holes, which are respectively located on both sides of the working face. The grouting diffusion radius is 100 - 150 m, and the grouting holes are arranged along the inflection point of the surface subsidence basin.

[0012] Preferably, when the length of the working face is 200 m - 400 m, add grouting holes in the middle of the working face, and the grouting holes are distributed along the inflection point of the surface subsidence basin.

[0013] Preferably, in Step 3, conduct directional drilling according to the main key stratum layer and the separated zone. The borehole diameter is 300 mm. The grouting holes for the first layer enter the separated zone. According to the filling material ratio in Step 2, the filling material ratio is gangue: gasification slag: fly ash: cement = 1:4.2:4.2:0.6. The grouting pump grouts into the grouting holes for the first layer at a pumping pressure of 3 MPa on the ground.

[0014] Preferably, in Step 4, after the grouting of the grouting holes for the first layer is completed, let it stand for a time T. Install a 270 - mm casing in the grouting holes for the first layer, and conduct the construction of the grouting holes for the second layer. Conduct drilling operations according to the calculated heights of the fissure zone and the caving zone. The drilling length of the grouting holes for the second layer is H2.

[0015] Preferably, determine the filling material ratio according to the caving zone and the fissure zone. The grouting pump applies a pumping pressure of 10 MPa on the ground to transport the slurry and grout into the grouting holes for the second layer.

[0016] Preferably, calculate the estimated heights of the fissure zone and the caving zone according to the formula:

[0017] When the mining height M ≤ 3.5 m, the estimated height H L of the fissure zone and the estimated height H K of the caving zone are respectively:

[0018] H L =(100M / (0.35M + 6.19)) ± 5.47

[0019] H K=(100M / (-7.71M + 42.44)) ± 2.38

[0020] When the mining height 3.5m < M < 6m, the estimated height H of the fissure zone L and the estimated height H of the caving zone K are respectively

[0021] H L =(100M / (-0.95M + 10.82)) ± 14.57

[0022] H K =(100M / (-1.77M + 26.04)) ± 7.90

[0023] When the mining height M ≥ 6m, the estimated height H of the fissure zone L and the estimated height H of the caving zone K are respectively

[0024] H L =(100M / (-0.77M + 12.52)) ± 28.5

[0025] H K =(100M / (-6.51M + 66.35)) ± 4.47.

[0026] Preferably, the method is applicable to the situation where there are thick and hard rock strata in the overlying strata of the actual coal seam.

[0027] The present invention discloses the following technical effects: A method for grouting and filling in a stepped and differentiated manner in different zones of overlying strata provided by the present invention has certain innovation and feasibility. Based on the traditional grouting and filling mining of overlying strata separation, after low-pressure grouting in the separation zone and waiting for the grouting slurry to fully solidify, drill holes through the filled separation zone and continue to drill holes into the caving zone and fissure zone on the basis of the original drill holes, and at the same time conduct high-pressure grouting, and complete the stepped and differentiated grouting and filling of the "three zones" of overlying strata under the action of the coal seam dip angle and the self-flow of the slurry. The present invention can have ultra-long drill holes, multi-purpose use of one hole, stepped and layered grouting, better grouting and subsidence reduction effect, simpler slurry conveying pipeline, further reducing the filling cost, and promoting the safe and green mining of coal. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0029] Figure 1 It is a schematic diagram of the coal seam strike method of the present invention;

[0030] Figure 2 Schematic diagram of grouting in the bedding separation area of the coal seam of the present invention;

[0031] Figure 3 Schematic diagram of grouting in the caving zone and fissure zone of the coal seam of the present invention;

[0032] Figure 4 Schematic diagram of the layout of the plane positions of the grouting holes of the present invention;

[0033] Wherein, 1. Grouting pump; 2. First-layer grouting borehole; 3. Second-layer grouting borehole; 4. Bedding separation area; 5. Fissure zone; 6. Caving zone; 7. Coal seam. Detailed implementation manners

[0034] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts shall fall within the protection scope of the present invention.

[0035] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific implementation manners.

[0036] The present invention provides a method for grouting and filling in a layered and gradient-differentiated manner in overlying strata, which is characterized by including the following steps:

[0037] Step 1. Determine the layer position of the main key stratum: After construction, take cores for mechanical tests to determine the layer position of the main key stratum. The distance from the layer position of the main key stratum to the ground is H1, and H1 is the length of the first grouting borehole 2;

[0038] Step 2. Preparation before grouting: Determine the plane positions of the grouting holes, and conduct indoor simulation tests according to the plane positions of the grouting holes to determine the mixing ratio of the filling materials for the layered and gradient grouting in overlying strata and the standing time T after grouting;

[0039] Step 3. Directional borehole grouting: Grout according to the mixing ratio in Step 2 through the grouting pump 1 and the first-layer grouting borehole 2;

[0040] Step 4. Second-layer grouting: After standing for the time T in Step 3, set the second-layer grouting borehole 3, and conduct second-layer grouting through the grouting pump 1 and the second-layer grouting borehole 3. The grouting filling operation ends when the slurry forms a saturated compaction body by precipitation in the caving zone.

[0041] For the further optimized solution, in order to determine the main key strata horizons and the separated strata development sections, in step 1, according to the comprehensive hydrogeological columnar section of the mining mine, the lithology comparison method is adopted to infer the separated strata grouting area based on the rock stratum structure. To further ensure the accuracy of the data, after drilling construction, core sampling is carried out for mechanical tests, and the main key strata horizons and the separated strata area 4 are determined according to the drilling mud loss situation and the core situation.

[0042] For the further optimized solution, in order to better control the subsidence of the working face, in step 2, before the caving of the goaf, the first-layer grouting borehole 2 is constructed. The plane position of the grouting hole must be within the range of the separated strata area 4. There are two grouting holes, which are respectively located on both sides of the working face. The grouting diffusion radius is 100 - 150 m, and the grouting holes are arranged along the inflection point of the surface subsidence basin.

[0043] For the further optimized solution, when the length of the working face is 200 m - 400 m, in order to better control the subsidence of the whole working face, grouting holes can be added in the middle of the working face, and the grouting holes are distributed along the inflection point of the surface subsidence basin.

[0044] For the further optimized solution, in order to achieve low-pressure grouting of the separated strata area 4, in step 3, directional drilling is carried out according to the main key strata horizons and the separated strata development sections. The borehole diameter is 300 mm, and the first-layer grouting borehole 2 enters the separated strata area 4. According to the filling material ratio in step 2, the filling material ratio is gangue : gasification slag : fly ash : cement = 1 : 4.2 : 4.2 : 0.6. The material ratio ensures the stability of the slurry. The grouting pump 1 grouts into the first-layer grouting borehole 2 at a pumping pressure of 3 MPa on the ground.

[0045] For the further optimized solution, in order to ensure the multi-purpose use of the ultra-long borehole, the slurry conveying pipeline is simpler, and the filling cost is further reduced. In step 4, after the first-layer grouting borehole 2 is grouted, the static time T is set. A 270-mm casing is installed in the first-layer grouting borehole 2, and the second-layer grouting borehole 3 is constructed. Drilling operations are carried out according to the estimated heights of the fractured zone 5 and the caving zone 6. The drilling length of the second-layer grouting borehole 3 is H2.

[0046] For the further optimized solution, in order to complete the stepped differential grouting filling of the overlying strata under the action of the inclination of the coal seam 7 and the self-flowing of the slurry, so that the grouting subsidence reduction effect is better, the filling material ratio is determined according to the caving zone and the fractured zone 5. The grouting pump 1 grouts the slurry into the second-layer grouting borehole 3 at a pumping pressure of 10 MPa on the ground. After the slurry reaches the fractured zone 5, it spreads and finally enters the caving zone 6 to fill the goaf after caving. The grouting filling operation ends until the slurry forms a saturated compaction body when precipitating in the caving zone.

[0047] For the further optimized solution, in order to obtain the estimated heights of the fractured zone 5 and the caving zone 6, the estimated heights of the fractured zone 5 and the caving zone 6 are calculated according to the formula:

[0048] When the mining height M ≤ 3.5 m, the estimated height H of the fissure zone 5 L and the estimated height H of the caving zone 6 K are respectively:

[0049] H L =(100M / (0.35M + 6.19)) ± 5.47

[0050] H K =(100M / (-7.71M + 42.44)) ± 2.38

[0051] When the mining height 3.5 m < M < 6 m, the estimated height H of the fissure zone 5 L and the estimated height H of the caving zone 6 K are respectively:

[0052] H L =(100M / (-0.95M + 10.82)) ± 14.57

[0053] H K =(100M / (-1.77M + 26.04)) ± 7.90

[0054] When the mining height M ≥ 6 m, the estimated height H of the fissure zone 5 L and the estimated height H of the caving zone 6 K are respectively:

[0055] H L =(100M / (-0.77M + 12.52)) ± 28.5

[0056] H K =(100M / (-6.51M + 66.35)) ± 4.47.

[0057] For the further optimized scheme, in order to ensure the filling effect, the mixing ratio of the filling material in the separated layer area 4 needs to have a short initial and final setting time and high strength, and the mixing ratio of the filling materials in the caving zone 6 and the fissure zone 5 needs to have good fluidity, and the slurry concentration can meet the designed grouting diffusion radius.

[0058] For the further optimized scheme, the grouting method of the present invention is applicable to the situation where there are thick and hard rock layers in the overlying strata of the actual coal seam 7.

[0059] Referring to Figures 1-4 , the present invention provides a method for grouting and filling in a hierarchical and differential manner in the overlying strata. According to the comprehensive hydrogeological columnar section of the mining mine, the lithology comparison method is adopted to infer the separated layer grouting area based on the rock layer structure. At the same time, after drilling construction, core sampling is carried out for mechanical tests, and the main key layer position and the separated layer development section are determined according to the drilling mud loss situation and the core situation, so as to determine that the length of the first grouting borehole 2 is the distance H1 from the ground to the main key layer position;

[0060] Before the gob collapses, the construction of the first-layer grouting boreholes 2 is carried out. One grouting hole is arranged on each side of the working face, so that the grouting diffusion radius is 100 - 150 m, ensuring that the plane position of the grouting hole is within the range of the area where the separation develops. According to the arrangement method of the plane position of the grouting hole, an indoor simulation test is carried out to determine the filling material ratio of the hierarchical grouting in the overlying strata. According to the initial and final setting times of the filling material in the separation zone 4, the standing time T after the grouting in the separation zone 4 is completed is determined;

[0061] Directional boreholes are drilled according to the main key stratum position and the separation development section. After the first-layer grouting boreholes 2 enter the separation zone 4, grouting is carried out by the ground grouting pump 1 according to the filling material ratio in the separation zone 4;

[0062] After grouting in the separation zone 4 for T, a casing is installed on the basis of the first-layer grouting boreholes 2, and the construction of the second-layer grouting boreholes 3 is continued. Drilling operations are carried out according to the estimated heights of the fracture zone 5 and the caving zone 6. Drilling stops when the drilling length of the second-layer grouting boreholes 3 reaches the theoretical length H2;

[0063] According to the filling material ratio of the caving zone 6 and the fracture zone 5, the ground grouting pump conveys the slurry. After the slurry reaches the fracture zone 5, it spreads and finally enters the caving zone 6 to fill the gob after caving. The grouting filling operation ends until the slurry precipitates in the caving zone 6 to form a saturated compaction body.

[0064] A method for hierarchical differential grouting filling in the overlying strata provided by the present invention has certain innovation and feasibility. On the basis of the traditional overlying strata separation grouting filling mining, after low-pressure grouting in the separation zone 4 and waiting for the filling slurry to fully solidify, drilling continues through the filled separation zone 4 to the caving zone 6 and the fracture zone 5 on the basis of the original boreholes, and high-pressure grouting is carried out at the same time. Under the action of the inclination angle of the coal seam 7 and the self-flow of the slurry, the hierarchical differential grouting filling of the "three zones" in the overlying strata is completed. The present invention can drill ultra-long boreholes, use one borehole for multiple purposes, carry out hierarchical layered grouting, has a better grouting and subsidence reduction effect, the slurry conveying pipeline is simpler, further reduces the filling cost, and promotes the safe and green mining of coal.

[0065] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0066] The embodiments described above are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for grouting and filling in a stepped and differentiated manner in different zones of overlying strata, characterized in that, It includes the following steps: Step 1. Determine the horizon of the main key stratum: After construction, take cores for mechanical tests to determine the horizon of the main key stratum. The distance from the main key stratum to the ground is H1, and H1 is the length of the first grouting borehole (2). Step 2. Prepare before grouting: Determine the plane position of the grouting holes, and conduct indoor simulation tests according to the plane position of the grouting holes to determine the filling material ratio for hierarchical grouting in the overlying strata and the standing time T after grouting. Step 3. Directional borehole grouting: Grout according to the material ratio in Step 2 through the grouting pump (1) and the first grouting borehole (2). Step 4. Second-layer grouting: After the standing time T in Step 3, set up the second-layer grouting borehole (3), and conduct second-layer grouting through the grouting pump (1) and the second-layer grouting borehole (3). The grouting filling operation ends when the slurry forms a saturated compaction body in the caving zone. In Step 4, after the first-layer grouting borehole (2) is grouted and the standing time T is reached, install a 270-mm casing in the first-layer grouting borehole (2), conduct the construction of the second-layer grouting borehole (3), and conduct drilling operations according to the calculated heights of the fissure zone (5) and the caving zone (6). The drilling length of the second-layer grouting borehole (3) is H2.

2. A method for grouting and filling in a stepped differential manner in different zones of overlying strata according to claim 1, characterized in that: In Step 1, take cores for mechanical tests after drilling construction, and determine the horizon of the main key stratum and the separated zone (4) according to the mud loss situation and core situation of the borehole.

3. A method for grouting and filling in a stepped and differentiated manner in different zones of overlying strata according to claim 2, characterized in that: In Step 2, construct the first-layer grouting borehole (2) before the caving in the goaf. The plane position of the grouting holes is located in the separated zone (4). There are two grouting holes, which are respectively located on both sides of the working face. The grouting diffusion radius is 100 - 150 m, and the grouting holes are set along the inflection point of the surface subsidence basin.

4. A method for grouting and filling in a stepped differential manner in different zones of overlying strata according to claim 3, characterized in that: When the length of the working face is 200 m - 400 m, add grouting holes in the middle of the working face, and the grouting holes are distributed along the inflection point of the surface subsidence basin.

5. A method for stepped differential grouting and filling in overlying strata according to claim 2, characterized in that: In Step 3, conduct directional drilling according to the horizon of the main key stratum and the separated zone (4). The borehole diameter is 300 mm. The first-layer grouting borehole (2) enters the separated zone (4). According to the filling material ratio in Step 2, the filling material ratio is gangue: gasification slag: fly ash: cement = 1:4.2:4.2:0.

6. The grouting pump (1) grouts into the first-layer grouting borehole (2) at a pumping pressure of 3 MPa on the ground.

6. The differential grouting and filling method for hierarchical zoning of overlying strata according to claim 1, characterized in that: Determine the filling material ratio according to the caving zone (6) and the fissure zone (5). The grouting pump (1) applies a pumping pressure of 10 MPa on the ground to transport the slurry to grout into the second-layer grouting borehole (3).

7. A method for grouting and filling in a stepped and differentiated manner in different zones of overlying strata according to claim 6, characterized in that: Calculate the estimated heights of the fissure zone (5) and the caving zone (6) according to the formula: When the mining height M ≤ 3.5 m, the estimated height HL of the fissure zone (5) and the estimated height H of the caving zone (6) K are respectively: H L = (100M / (0.35M + 6.19)) ± 5.47 H K =(100M / (-7.71M + 42.44)) ± 2.38 When the mining height 3.5m < M < 6m, the estimated height H of the fissure zone (5) L and the estimated height H of the caving zone (6) K are respectively H L =(100M / (-0.95M + 10.82)) ± 14.57 H K =(100M / (-1.77M + 26.04)) ± 7.90 When the mining height M≥6m, the estimated height H of the fissure zone (5) L and the estimated height H of the caving zone (6) K are respectively H L =(100M / (-0.77M + 12.52)) ± 28.5 H K =(100M / (-6.51M + 66.35)) ± 4.

47.

8. A method for grouting and filling in a stepped differential manner in different zones of overlying strata according to any one of claims 1-7, characterized in that: The method is applicable to the situation where there are thick and hard strata in the overlying strata of the actual coal seam (7).

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