A method for controlling water inrush from the floor of coal seams

Abstract

The present invention discloses a method for controlling water inrush from the coal seam floor. The method includes the following steps: First, determine the location of the area to be reinforced; Second, collect the original apparent resistivity of the area to be reinforced before reinforcement; Third, perform grouting reinforcement on the area to be reinforced; Fourth, determine the effective reinforcement area within the area to be reinforced after grouting reinforcement; Fifth, judge the water inrush risk of the area to be reinforced according to the effective reinforcement area within the area to be reinforced after grouting reinforcement; Sixth, perform supplementary grouting reinforcement on the area to be reinforced; Seventh, complete the grouting reinforcement of the area to be reinforced. By measuring the apparent resistivity of the area to be reinforced before and after reinforcement, the present invention judges whether there is a water inrush risk in the area to be reinforced after reinforcement. If there is a water inrush risk, supplementary grouting reinforcement is performed on the area to be reinforced until there is no water inrush risk in the area to be reinforced, thus eliminating the water inrush risk caused by the water inrush from the floor. The treatment effect is good, and the safety of coal mine production is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of controlling water inrush from coal seam floor, and particularly relates to a method for controlling water inrush from coal seam floor. Background Art

[0002] Safely and efficiently mining coal is a major event related to the national economy and people's livelihood. China is one of the countries with the largest coal production in the world. At the same time, the geological and hydrogeological conditions of coal mines in China are very complex. During the mining process of many coal seams, they are threatened by various water bodies. In recent years, with the continuous increase in the mining depth, intensity, and breadth of coal mine production, the hydrogeological conditions of coalfields have become increasingly complex. The confined water in the floor poses an increasingly serious threat to the safe production of coal mines. The adverse factors of water seriously restrict the sustainable development of the coal industry and affect environmental projects such as water-preserved coal mining. Up to now, mine water disasters are still major hidden dangers in coal mine safety production. The main measures for preventing and controlling Ordovician karst water disasters mainly include dewatering and pressure reduction, curtain grouting, and floor grouting reinforcement and transformation. The three technologies for preventing and controlling floor water disasters mainly target different aquifer characteristics. Floor grouting reinforcement and transformation is to construct grouting holes and grout them. Through the filling of grout, squeezing the cracks and small solution cavities in the floor rock layer, and after coagulation and cementation, the floor of the stope is reinforced, enhancing the ability of the floor rock layer to resist the damage of mining and high-confined water, and preventing water inrush accidents from occurring in the high-confined aquifer in the floor. However, the commonly used grouting reinforcement methods at present only simply grout and reinforce the coal seam floor, and do not evaluate and optimize the grouting reinforcement effect, and cannot ensure the grouting reinforcement effect of the floor. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a method for controlling water inrush from coal seam floor in view of the deficiencies in the above-mentioned prior art. The method steps are simple. By measuring the apparent resistivity before and after reinforcement of the area to be reinforced, it is judged whether there is a risk of water inrush in the area to be reinforced after reinforcement. If there is a risk of water inrush, additional grouting reinforcement is carried out on the area to be reinforced until there is no risk of water inrush in the area to be reinforced, eliminating the water inrush danger caused by water inrush from the floor, with good treatment effect and improving the safety of coal mine production.

[0004] To solve the above technical problem, the technical solution adopted by the present invention is: A method for controlling water inrush from coal seam floor, characterized in that the method includes the following steps:

[0005] Step 1: Determine the location of the area to be reinforced;

[0006] Step 2: Collect the original apparent resistivity of the area to be reinforced before reinforcement;

[0007] Step 3: Carry out grouting reinforcement on the area to be reinforced;

[0008] Step 4: Determine the effective reinforcement area within the area to be reinforced after grouting reinforcement;

[0009] Step Five: Judge the water inrush risk of the area to be reinforced according to the effective reinforcement area in the area to be reinforced after grouting reinforcement;

[0010] Step Six: Conduct supplementary grouting reinforcement on the area to be reinforced;

[0011] Step Seven: Complete the grouting reinforcement of the area to be reinforced.

[0012] The above method for controlling water inrush from the coal seam floor is characterized in that: in Step One, the position of the area to be reinforced is determined, and the specific process is as follows:

[0013] Determine the horizons of the coal seam floor, water-resisting layer and aquifer under the coal mining face. The area where the water-resisting layer is located in the vertically upward moving area is the area to be reinforced.

[0014] The above method for controlling water inrush from the coal seam floor is characterized in that: in Step Two, the original apparent resistivity of the area to be reinforced before reinforcement is collected, and the specific process is as follows:

[0015] Step 201: Arrange M groups of measuring points in sequence from the back to the front along the length direction of the coal mining face. Each group of measuring points includes a first measuring point located in the transportation roadway and a second measuring point located in the return airway; where M is a positive integer and M≥3;

[0016] Step 202: Measure the apparent resistivity of the area to be reinforced at M groups of measuring points respectively to obtain a set of M original apparent resistivity sequences of the area to be reinforced. The measurement methods of the apparent resistivity of the area to be reinforced at M groups of measuring points are the same. When measuring the apparent resistivity of the area to be reinforced at the mth group of measuring points, it mainly includes the following steps:

[0017] Step 2021: Place the transient electromagnetic instrument at the first measuring point of the mth group of measuring points, make the horizontal plane where the transmitting coil of the transient electromagnetic instrument is located perpendicular to the vertical plane where the central axis of the transportation roadway is located, and then rotate the transmitting coil of the transient electromagnetic instrument clockwise by 90°. During the rotation of the transmitting coil of the transient electromagnetic instrument, the transient electromagnetic instrument measures the apparent resistivity of the area to be reinforced at a set measurement interval to obtain the original apparent resistivity of the area to be reinforced at different angles at the first measuring point of the mth group of measuring points; where m is the measuring point number, 1≤m≤M, and the measurement interval is 10°-15°;

[0018] Step 2022: Place the transient electromagnetic instrument at the second measuring point of the m-th group of measuring points, such that the horizontal plane where the transmitting coil of the transient electromagnetic instrument is located is perpendicularly arranged with respect to the vertical plane where the central axis of the return airway is located. Then, rotate the transmitting coil of the transient electromagnetic instrument counterclockwise by 90°. During the rotation of the transmitting coil of the transient electromagnetic instrument, the transient electromagnetic instrument measures the apparent resistivity of the area to be reinforced at a set measurement interval, obtaining the original apparent resistivity of the area to be reinforced at different angles at the second measuring point of the m-th group of measuring points.

[0019] Step 2023: Arrange the original apparent resistivity of the area to be reinforced at different angles at the first measuring point of the m-th group of measuring points obtained in Step 2021 and the original apparent resistivity of the area to be reinforced at different angles at the second measuring point of the m-th group of measuring points obtained in Step 2022 in the order of the measurement time, obtaining the original apparent resistivity sequence set ρ of the area to be reinforced at the m-th group of measuring points. 0m , the original apparent resistivity sequence set ρ 0m includes A original apparent resistivities. The a-th original apparent resistivity in the original apparent resistivity sequence set ρ 0m is denoted as ρ 0ma ; where A is a positive integer, a is the original apparent resistivity number, and 1 ≤ a ≤ A.

[0020] The above-described method for controlling water inrush from the coal seam floor is characterized in that: in Step three, grouting reinforcement is carried out on the area to be reinforced, which mainly includes the following steps:

[0021] Step 301: Determine the aperture, starting position, and ending position of the test borehole to be constructed in the area to be reinforced. Construct a test borehole in the area to be reinforced and carry out grouting reinforcement in the test borehole; wherein, the test borehole is arranged near the left end of the area to be reinforced, and the center of the test borehole is located on the horizontal center line of the area to be reinforced.

[0022] Step 302: According to the method described in Step 202, measure the apparent resistivity of the area to be reinforced again at M groups of measuring points, obtaining M first apparent resistivity sequence sets of the area to be reinforced; wherein, when measuring the apparent resistivity of the area to be reinforced at the m-th group of measuring points, obtaining the first apparent resistivity sequence set ρ 1m of the area to be reinforced at the m-th group of measuring points. The first apparent resistivity sequence set ρ 1m includes A first apparent resistivities. The a-th first apparent resistivity in the first apparent resistivity sequence set ρ 1m is denoted as ρ 1ma ;

[0023] Step 303: Perform data processing on the first apparent resistivity sequence sets and the original apparent resistivity sequence sets at M measurement points to obtain the effective reinforcement area and effective reinforcement width of the test boreholes at M measurement points. The methods for performing data processing on the first apparent resistivity sequence sets and the original apparent resistivity sequence sets at M measurement points are the same. For the first apparent resistivity sequence set ρ 1m and the original apparent resistivity sequence set ρ 0m at the m-th measurement point, the data processing mainly includes the following steps:

[0024] Step 3031: Match the A first apparent resistivities in the first apparent resistivity sequence set ρ 1m one by one with the A original apparent resistivities in the original apparent resistivity sequence set ρ 0m , and calculate the increase amplitudes of the A first apparent resistivities at the m-th measurement point respectively. Among them, the calculation methods of the increase amplitudes of the A first apparent resistivities are the same. When calculating the increase amplitude of the a-th first apparent resistivity, use the formula to calculate the increase amplitude Z 1a of the a-th first apparent resistivity;

[0025] Step 3032: Determine the effective reinforcement area of the test borehole at the m-th measurement point according to the increase amplitudes of the A first apparent resistivities. Among them, the basis for dividing the effective reinforcement area of the test borehole is: when the increase amplitude Z 1ma of the a-th first apparent resistivity ρ 1a ≥ 10%, the area corresponding to the a-th first apparent resistivity is located within the effective reinforcement area of the test borehole;

[0026] Step 3033: Measure the average width of the effective reinforcement area of the test borehole at the m-th measurement point as the effective reinforcement width b 1m of the test borehole at the m-th measurement point;

[0027] Step 304: Calculate the average effective reinforcement width of the test boreholes in the area to be reinforced according to the formula

[0028] Step 305: Determine the number of grouting holes to be constructed in the area to be reinforced according to the formula . Among them, represents rounding up, and B1 is the maximum width of the area to be reinforced;

[0029] Step 306: Construct N grouting holes along the length direction in the area to be reinforced, and perform grouting reinforcement in all N grouting holes to complete the grouting reinforcement of the area to be reinforced. Among them, the structure of the grouting holes is the same as that of the test boreholes. The centers of the N grouting holes are all on the same horizontal plane as the center of the test borehole, and the hole spacing between two adjacent grouting holes among the N grouting holes is k,

[0030] The above method for controlling water inrush from the coal seam floor is characterized in that: in step four, to determine the effective reinforcement area within the area to be reinforced after grouting reinforcement, the specific process is as follows:

[0031] Step 401: According to the method described in step 302, measure the apparent resistivity of the area to be reinforced again at M groups of measuring points, and obtain a set of second apparent resistivity sequences for M areas to be reinforced; among them, measure the apparent resistivity of the area to be reinforced at the m-th group of measuring points, and obtain a set of second apparent resistivity sequences ρ 2m of the area to be reinforced at the m-th group of measuring points, where the set of second apparent resistivity sequences ρ 2m includes A second apparent resistivities, and the a-th second apparent resistivity in the set of second apparent resistivity sequences ρ 2m is denoted as ρ 2ma ;

[0032] Step 402: According to the method described in step 303, perform data processing on the set of second apparent resistivity sequences and the set of original apparent resistivity sequences at M groups of measuring points to determine the effective reinforcement areas of N grouting holes at M groups of measuring points.

[0033] The above method for controlling water inrush from the coal seam floor is characterized in that: in step five, judge the water inrush risk of the area to be reinforced according to the effective reinforcement area within the area to be reinforced after grouting reinforcement, and the specific process is as follows:

[0034] When the effective reinforcement areas of any two adjacent grouting holes at a certain group of measuring points among M groups of measuring points are not connected, the area to be reinforced has a water inrush risk, and step six is executed;

[0035] When the effective reinforcement areas of two adjacent grouting holes at each group of measuring points among M groups of measuring points are all connected, the area to be reinforced has no water inrush risk, and step seven is executed.

[0036] The above method for controlling water inrush from the coal seam floor is characterized in that: in step six, perform supplementary grouting reinforcement on the area to be reinforced, which mainly includes the following steps:

[0037] Construct supplementary grouting holes between two adjacent grouting holes where the effective reinforcement areas are not connected, and perform supplementary grouting in the supplementary grouting holes to make the effective reinforcement areas of two adjacent grouting holes at M groups of measuring points all connected.

[0038] The above-described method for controlling water inrush from the coal seam floor is characterized in that: in step 301, both the starting position and the ending position of the test borehole are in front of the open-off cut of the working face. The starting position of the test borehole is determined by the width of the coal mining face. The distance L1 between the starting position of the test borehole and the open-off cut of the working face is L1 = 2B0 + L0, where B0 is the width of the coal mining face, and L0 is the distance between the ending position of the test borehole and the open-off cut of the working face. The value range of L0 is 20m to 40m.

[0039] The beneficial effects of the present invention are as follows: By determining the position of the area to be reinforced and measuring the apparent resistivity before and after grouting reinforcement of the area to be reinforced, the original apparent resistivity sequence set and the second apparent resistivity sequence set of the area to be reinforced are obtained. According to the original apparent resistivity sequence set and the second apparent resistivity sequence set of the area to be reinforced, the effective reinforcement area within the area to be reinforced after grouting reinforcement is determined, and it is judged whether there is a risk of water inrush in the area to be reinforced after reinforcement. If there is still a risk of water inrush in the area to be reinforced after reinforcement, supplementary grouting reinforcement is carried out on the area to be reinforced, so that there is no risk of water inrush in the area to be reinforced after reinforcement, the water inrush risk caused by water inrush from the floor is eliminated, the treatment effect is good, it has a practical and positive guiding role in the safe production of coal mines, and improves the safety of coal mine production.

[0040] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a flow chart of the method of the present invention.

[0042] Figure 2 It is a structural schematic diagram of the present invention.

[0043] Figure 3 It is a schematic diagram of the positional relationship among the area to be reinforced, the transportation roadway, the return airway, the test borehole and the grouting hole of the present invention.

[0044] DESCRIPTION OF THE REFERENCE NUMERALS:

[0045] 1 - Coal mining face; 2 - Coal seam floor; 3 - Aquifuge;

[0046] 4 - Aquifer; 5 - Vertically upward movement area; 6 - Area to be reinforced;

[0047] 6-1 - Reinforcement section; 6-2 - Safety section; 7 - Transportation roadway;

[0048] 8 - Return airway; 9 - First measuring point; 10 - Second measuring point;

[0049] 11 - Transient electromagnetic instrument; 12 - Test borehole; 13 - Grouting hole. DETAILED DESCRIPTION OF THE INVENTION

[0050] As Figure 1 shown, a method for controlling water inrush from the coal seam floor according to the present invention includes the following steps:

[0051] Step 1: Determine the location of the area to be reinforced;

[0052] Step 2: Collect the original apparent resistivity of the area to be reinforced before reinforcement;

[0053] Step 3: Inject grout to reinforce the area to be reinforced;

[0054] Step 4: Determine the effective reinforcement area within the area to be reinforced after grouting reinforcement;

[0055] Step 5: Judge the water inrush risk of the area to be reinforced according to the effective reinforcement area within the area to be reinforced after grouting reinforcement;

[0056] Step 6: Inject supplementary grout to reinforce the area to be reinforced;

[0057] Step 7: Complete the grouting reinforcement of the area to be reinforced.

[0058] The beneficial effect of the present invention is that by determining the location of the area 6 to be reinforced and measuring the apparent resistivity before and after grouting reinforcement of the area 6 to be reinforced, the original apparent resistivity sequence set and the second apparent resistivity sequence set of the area 6 to be reinforced are obtained, and the effective reinforcement area within the area 6 to be reinforced after grouting reinforcement is determined according to the original apparent resistivity sequence set and the second apparent resistivity sequence set of the area 6 to be reinforced, and it is judged whether there is a water inrush risk in the area 6 to be reinforced after reinforcement. If there is still a water inrush risk in the area 6 to be reinforced after reinforcement, supplementary grout injection is carried out on the area to be reinforced, so that there is no water inrush risk in the area 6 to be reinforced after reinforcement, the water inrush risk caused by the water inrush from the floor is eliminated, the treatment effect is good, it has a practical and positive guiding role for the safe production of coal mines, and improves the safety of coal mine production.

[0059] As Figure 2 shown, in this embodiment, the process of determining the location of the area to be reinforced in Step 1 is as follows:

[0060] Determine the horizons of the coal seam floor 2, the water - resistant layer 3 and the aquifer 4 below the coal mining face 1. The area where the water - resistant layer 3 is located within the vertically upward movement area 5 is the area 6 to be reinforced.

[0061] In this embodiment, it should be noted that during the mining process of the coal mining face 1, the deformation and failure of the water-resisting layer 3 below the coal mining face 1 mainly show three different change forms: First, the water-resisting layer 3 remains intact before the coal mining face 1 is mined; Second, the water-resisting layer 3 gradually bends and deforms during the mining process of the coal mining face 1; Finally, the water-resisting layer 3 is significantly broken after the coal mining face 1 is mined, and the water-resisting layer 3 within the vertical upward movement area 5 is the first to break. Therefore, the area of the water-resisting layer 3 within the vertical upward movement area 5 is used as the area to be reinforced 6, and grouting reinforcement is carried out on the area to be reinforced 6. The grout injected during the grouting reinforcement diffuses within the area to be reinforced 6 and mixes and solidifies with the rock mass in the area to be reinforced 6, improving the mechanical properties of the rock mass of the water-resisting layer 3, increasing the anti-seepage performance of the water-resisting layer 3, enhancing the ability of the water-resisting layer 3 to resist deformation, and effectively avoiding the water inrush from the coal seam floor 2 caused by the breakage of the water-resisting layer 3.

[0062] In this embodiment, during actual use, the maximum width of the area to be reinforced 6 is used as the overall width of the area to be reinforced 6, making the area to be reinforced 6 in a rectangular structure, which is convenient for ensuring the reinforcement effect of the area to be reinforced 6.

[0063] As Figure 2 and Figure 3 shown, in this embodiment, in step two, the original apparent resistivity of the area to be reinforced before reinforcement is collected, and the specific process is as follows:

[0064] Step 201: M groups of measuring points are arranged in sequence from the back to the front along the length direction of the coal mining face 1. Each group of measuring points includes a first measuring point 9 located in the transportation roadway 7 and a second measuring point 10 located in the return airway 8; where M is a positive integer and M≥3;

[0065] Step 202: The apparent resistivity of the area to be reinforced 6 is measured at M groups of measuring points respectively, and M original apparent resistivity sequence sets of the area to be reinforced 6 are obtained. The measuring methods of the apparent resistivity of the area to be reinforced 6 at M groups of measuring points are the same. When measuring the apparent resistivity of the area to be reinforced 6 at the m-th group of measuring points, it mainly includes the following steps:

[0066] Step 2021: Place the transient electromagnetic instrument 11 at the first measuring point 9 of the m-th group of measuring points, make the horizontal plane where the transmitting coil of the transient electromagnetic instrument 11 is located perpendicular to the vertical plane where the central axis of the transportation roadway 7 is located, and then rotate the transmitting coil of the transient electromagnetic instrument 11 clockwise by 90°. During the rotation of the transmitting coil of the transient electromagnetic instrument 11, the transient electromagnetic instrument 11 measures the apparent resistivity of the area to be reinforced 6 at a set measurement interval, and obtains the original apparent resistivity of the area to be reinforced 6 at different angles at the first measuring point 9 of the m-th group of measuring points; where m is the measuring point number, 1≤m≤M, and the measurement interval is 10° - 15°;

[0067] Step 2022: Place the transient electromagnetic instrument 11 at the second measuring point 10 of the m-th group of measuring points, such that the horizontal plane where the transmitting coil of the transient electromagnetic instrument 11 is located is perpendicularly arranged with respect to the vertical plane where the central axis of the return airway 8 is located. Then, rotate the transmitting coil of the transient electromagnetic instrument 11 counterclockwise by 90°. During the rotation of the transmitting coil of the transient electromagnetic instrument 11, the transient electromagnetic instrument 11 measures the apparent resistivity of the area to be reinforced 6 at a set measurement interval, obtaining the original apparent resistivity of the area to be reinforced 6 at different angles at the second measuring point 10 of the m-th group of measuring points;

[0068] Step 2023: Arrange the original apparent resistivity of the area to be reinforced 6 at different angles at the first measuring point 9 of the m-th group of measuring points obtained in Step 2021 and the original apparent resistivity of the area to be reinforced 6 at different angles at the second measuring point 10 of the m-th group of measuring points obtained in Step 2022 in the order of the measurement time, obtaining the original apparent resistivity sequence set ρ of the area to be reinforced 6 at the m-th group of measuring points 0m of the area to be reinforced 6, where the original apparent resistivity sequence set ρ 0m includes A original apparent resistivities, and the a-th original apparent resistivity in the original apparent resistivity sequence set ρ 0m is denoted as ρ 0ma ; where A is a positive integer, a is the original apparent resistivity number, and 1 ≤ a ≤ A.

[0069] In this embodiment, it should be noted that when using the transient electromagnetic instrument 11 to measure the apparent resistivity of the area to be reinforced 6, based on the principle of electromagnetic induction, a high-power transient electromagnetic instrument 11 is placed in the haulage roadway 7 or the return airway 8. The sudden change of the large current in the transient electromagnetic instrument 11 excites a transient electromagnetic field. The low-frequency part of these transient electromagnetic fields can effectively enter the rock stratum where the area to be reinforced 6 is located, inducing a secondary induced electromotive force in the rock stratum where the area to be reinforced 6 is located. This secondary induced electromotive force is related to the conductivity of the rock stratum where the area to be reinforced 6 is located. This secondary induced electromotive force can effectively pass through the rock stratum and enter the receiving coil of the transient electromagnetic instrument 11 again. By measuring the secondary induced electromotive force, the apparent resistivity of the rock stratum where the area to be reinforced 6 is located is obtained. The measurement is convenient, without the need for other drilling operations in the coal mine roadway, saving time and effort, and having high measurement accuracy, which is convenient for popularization and use;

[0070] In step 201, M groups of measurement points are arranged in sequence from the back to the front along the length direction of the area 6 to be strengthened. The first group of measurement points in the M groups of measurement points and the termination position of the test borehole 12 in the area 6 to be strengthened are located in the same vertical plane. The last group of measurement points in the M groups of measurement points and the starting position of the test borehole 12 in the area 6 to be strengthened are located in the same vertical plane. Each group of measurement points includes a first measurement point 9 and a second measurement point 10. By measuring the apparent resistivity of the area 6 to be strengthened around each group of measurement points at the first measurement point 9 and the second measurement point 10 of each group of measurement points respectively, the apparent resistivity of the area 6 to be strengthened within a section around each group of measurement points can be measured in all directions, with a wide measurement range and high measurement accuracy.

[0071] By measuring the apparent resistivity of the area 6 to be strengthened at the M groups of measurement points respectively, it is convenient to evaluate the overall strengthening effect of the area 6 to be strengthened in the later stage, and the evaluation accuracy is high.

[0072] In step 202, when measuring the apparent resistivity of the area 6 to be strengthened at each measurement point, the transient electromagnetic instrument 11 needs to be rotated to ensure that the measurement range of the transient electromagnetic instrument 11 covers the entire area 6 to be strengthened.

[0073] In this embodiment, in step 2021, when the transmitting coil of the transient electromagnetic instrument 11 rotates clockwise by 90°, the transient electromagnetic instrument 11 rotates around its side away from the coal mining face 1. In step 2022, when the transmitting coil of the transient electromagnetic instrument 11 rotates counterclockwise by 90°, the transient electromagnetic instrument 11 rotates around its side away from the coal mining face 1.

[0074] As Figure 2 and Figure 3 shown, in this embodiment, in step three, grouting reinforcement is carried out on the area to be strengthened, which mainly includes the following steps:

[0075] Step 301: Determine the aperture, starting position and termination position of the test borehole 12 to be constructed in the area 6 to be strengthened, construct a test borehole 12 in the area 6 to be strengthened, and carry out grouting reinforcement in the test borehole 12. Among them, the test borehole 12 is arranged near the left end of the area 6 to be strengthened, and the center of the test borehole 12 is located on the horizontal center line of the area 6 to be strengthened.

[0076] Step 302: According to the method described in step 202, measure the apparent resistivity of the area 6 to be strengthened at the M groups of measurement points again to obtain a first set of apparent resistivity sequences of M areas 6 to be strengthened. Among them, when measuring the apparent resistivity of the area 6 to be strengthened at the mth group of measurement points, a first set of apparent resistivity sequences ρ 1m of the area 6 to be strengthened at the mth group of measurement points is obtained, and the first set of apparent resistivity sequences ρ 1m includes A first apparent resistivities, and the first set of apparent resistivity sequences ρ1m The a-th first apparent resistivity in it is denoted as ρ 1ma ;

[0077] Step 303: Process the first apparent resistivity sequence sets and the original apparent resistivity sequence sets at M groups of measuring points to obtain the effective reinforcement area and the effective reinforcement width of the test borehole 12 at M groups of measuring points; the methods for processing the first apparent resistivity sequence sets and the original apparent resistivity sequence sets at M groups of measuring points are the same. When processing the first apparent resistivity sequence set ρ 1m and the original apparent resistivity sequence set ρ 0m at the m-th group of measuring points, the following steps are mainly included:

[0078] Step 3031: Match the A first apparent resistivities in the first apparent resistivity sequence set ρ 1m one by one with the A original apparent resistivities in the original apparent resistivity sequence set ρ 0m , and calculate the increase amplitudes of the A first apparent resistivities at the m-th group of measuring points respectively; among them, the calculation methods of the increase amplitudes of the A first apparent resistivities are the same. When calculating the increase amplitude of the a-th first apparent resistivity, use the formula to calculate the increase amplitude Z 1a of the a-th first apparent resistivity;

[0079] Step 3032: Determine the effective reinforcement area of the test borehole 12 at the m-th group of measuring points according to the increase amplitudes of the A first apparent resistivities; among them, the basis for dividing the effective reinforcement area of the test borehole 12 is: when the increase amplitude Z 1ma of the a-th first apparent resistivity ρ 1a ≥10%, the area corresponding to the a-th first apparent resistivity is located within the effective reinforcement area of the test borehole 12;

[0080] Step 3033: Measure the average width of the effective reinforcement area of the test borehole 12 at the m-th group of measuring points as the effective reinforcement width b 1m of the test borehole 12 at the m-th group of measuring points;

[0081] Step 304: Calculate the average effective reinforcement width of the test borehole 12 in the area to be reinforced 6 according to the formula

[0082] Step 305: Determine the number of grouting holes 13 to be constructed in the area to be reinforced 6 according to the formula ; among them, means rounding up, and B1 is the maximum width of the area to be reinforced 6;

[0083] Step 306: Construct N grouting holes 13 along the length direction of the area 6 to be strengthened, and perform grouting reinforcement in all N grouting holes 13 to complete the grouting reinforcement of the area 6 to be strengthened; wherein, the structure of the grouting hole 13 is the same as that of the test drilling hole 12, the centers of the N grouting holes 13 are all on the same horizontal plane as the center of the test drilling hole 12, and the hole spacing between two adjacent grouting holes 13 among the N grouting holes 13 is k.

[0084] In this embodiment, in actual use, in step three, by constructing a test drilling hole 12 in the area 6 to be strengthened and performing grouting reinforcement in the test drilling hole 12, comparing the original apparent resistivity sequence set and the first apparent resistivity sequence set measured before and after the grouting reinforcement of the test drilling hole 12, the average effective reinforcement width of the test drilling hole 12 in the area 6 to be strengthened is determined. And determine the number of the constructed grouting holes 13 according to the average effective reinforcement width b1 of the test drilling hole 12 in the area 6 to be strengthened.

[0085] In this embodiment, the area 6 to be strengthened includes a reinforcement section 6-1 and a safety section 6-2. The test drilling hole 12 and the grouting holes 13 are both located in the reinforcement section 6-1. The safety section 6-2 is located between the reinforcement section 6-1 and the working face cutting roadway. The distance between the termination position of the test drilling hole 12 and the working face cutting roadway is the length of the safety section 6-2. By setting the safety section 6-2, it is avoided that the normal operation of the working face cutting roadway is affected when performing grouting operations on the test drilling hole 12 and the grouting holes 13 in the reinforcement section 6-1, leaving a safety range, and the safety performance is good.

[0086] In this embodiment, both the test drilling hole 12 and the grouting holes 13 are directional long-distance drilling holes. The aperture of the grouting hole 13 is equal to the aperture of the test drilling hole 12. The starting position of the grouting hole 13 is the same as the starting position of the test drilling hole 12, and the termination position of the grouting hole 13 is the same as the termination position of the test drilling hole 12.

[0087] In this embodiment, by performing grouting reinforcement in the grouting hole 13, the slurry is mixed and solidified with the rock mass in the area 6 to be strengthened, improving the rock mass mechanical properties of the water-resisting layer 3, increasing the anti-seepage performance of the water-resisting layer 3, enhancing the ability of the water-resisting layer 3 to resist deformation, and effectively avoiding the situation of water inrush from the coal seam floor 2 caused by the fracture of the water-resisting layer 3.

[0088] In this embodiment, in step four, to determine the effective reinforcement area in the area to be strengthened after grouting reinforcement, the specific process is as follows:

[0089] Step 401: According to the method described in step 302, measure the apparent resistivity of the area to be reinforced 6 again at M groups of measuring points, and obtain M sets of second apparent resistivity sequences of the area to be reinforced 6. Among them, when measuring the apparent resistivity of the area to be reinforced 6 at the m-th group of measuring points, obtain the second apparent resistivity sequence set ρ of the area to be reinforced 6 at the m-th group of measuring points 2m , the second apparent resistivity sequence set ρ 2m includes A second apparent resistivities. The a-th second apparent resistivity in the second apparent resistivity sequence set ρ 2m is denoted as ρ 2ma ;

[0090] Step 402: According to the method described in step 303, perform data processing on the second apparent resistivity sequence set and the original apparent resistivity sequence set at M groups of measuring points to determine the effective reinforcement areas of N grouting holes 13 at M groups of measuring points.

[0091] In this embodiment, in step four, the transient electromagnetic instrument 11 is used to measure the apparent resistivity of the area to be reinforced 6 after grouting reinforcement, and a set of second apparent resistivity sequences is obtained. By comparing the original apparent resistivity sequence set and the second apparent resistivity sequence set collected before and after the grouting reinforcement of the area to be reinforced 6, the effective reinforcement area of the area to be reinforced 6 is obtained. The measurement efficiency is high, and it can vividly and intuitively reflect the water inrush risk areas of the coal seam floor and the corresponding risk levels of each area, and the result accuracy is good.

[0092] In this embodiment, in step five, the water inrush risk level of the area to be reinforced is evaluated according to the effective reinforcement area in the area to be reinforced after grouting reinforcement. The specific process is as follows:

[0093] When the effective reinforcement areas of two adjacent grouting holes 13 do not communicate at any group of measuring points among the M groups of measuring points, there is a water inrush risk in the area to be reinforced 6, and step six is executed;

[0094] When the effective reinforcement areas of two adjacent grouting holes 13 communicate at each group of measuring points among the M groups of measuring points, there is no water inrush risk in the area to be reinforced 6, and step seven is executed.

[0095] In this embodiment, it should be noted that in step five, by observing whether the effective reinforcement areas of two adjacent grouting holes 13 in the area 6 to be reinforced after grouting reinforcement are connected, the water inrush risk degree of the area 6 to be reinforced during the coal mining face 1 mining period is evaluated, and the water inrush risk level of the area 6 to be reinforced after grouting reinforcement is obtained; when the effective reinforcement areas of two adjacent grouting holes 13 at each measurement point in the M groups of measurement points are all connected, it indicates that at this time, the effective reinforcement area of the area 6 to be reinforced covers the width of the area 6 to be reinforced, and the water - resisting layer 3 is less affected by the mining stress disturbance of the coal mining face 1. At this time, there is no water inrush risk in the area 6 to be reinforced; when there is any group of measurement points in the M groups of measurement points where the effective reinforcement areas of two adjacent grouting holes 13 are not connected, it indicates that at this time, the effective reinforcement area of the area 6 to be reinforced does not cover the width of the area 6 to be reinforced, and the water - resisting layer 3 is more affected by the mining stress disturbance of the coal mining face 1. At this time, there is a water inrush risk in the area 6 to be reinforced.

[0096] In this embodiment, in step six, supplementary grouting reinforcement is carried out on the area to be reinforced, which mainly includes the following steps:

[0097] Construct supplementary grouting holes between two adjacent grouting holes 13 whose effective reinforcement areas are not connected, and conduct supplementary grouting in the supplementary grouting holes to make the effective reinforcement areas of two adjacent grouting holes 13 at each measurement point in the M groups of measurement points all connected.

[0098] In this embodiment, both the starting position and the ending position of the test borehole 12 in step 301 are in front of the starting cut of the working face. The starting position of the test borehole 12 is determined by the width of the coal mining face 1. The distance L1 between the starting position of the test borehole 12 and the starting cut of the working face is L1 = 2B0 + L0, where B0 is the width of the coal mining face 1, and L0 is the distance between the ending position of the test borehole 12 and the starting cut of the working face. The value range of L0 is 20m to 40m.

[0099] The above - mentioned is only a preferred embodiment of the present invention, and does not impose any limitation on the present invention. Any simple modification, change, and equivalent structural change made to the above - mentioned embodiments according to the technical essence of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A method for controlling water inrush from the floor of a coal seam, characterized in that, The method comprises the following steps: Step 1, determine the position of the area to be reinforced; Step 2, collect the original apparent resistivity of the area to be reinforced before reinforcement; Step 3, perform grouting reinforcement on the area to be reinforced; Step 4, determine the effective reinforcement area within the area to be reinforced after grouting reinforcement; Step 5, judge the water inrush risk of the area to be reinforced according to the effective reinforcement area within the area to be reinforced after grouting reinforcement; Step 6, perform supplementary grouting reinforcement on the area to be reinforced; Step 7, complete the grouting reinforcement of the area to be reinforced; In Step 2, the process of collecting the original apparent resistivity of the area to be reinforced before reinforcement is as follows: Step 201, successively arrange M groups of measuring points from back to front along the length direction of the coal mining face (1), and each group of measuring points includes a first measuring point (9) located in the transportation roadway (7) and a second measuring point (10) located in the return airway (8); where M is a positive integer and M≥3; Step 202, measure the apparent resistivity of the area to be reinforced (6) at the M groups of measuring points respectively to obtain an original apparent resistivity sequence set of M areas to be reinforced (6); In Step 3, the grouting reinforcement of the area to be reinforced mainly includes the following steps: Step 301, determine the aperture, starting position and ending position of the test borehole (12) to be constructed within the area to be reinforced (6), construct a test borehole (12) within the area to be reinforced (6), and perform grouting reinforcement within the test borehole (12); Step 302, according to the method described in Step 202, measure the apparent resistivity of the area to be reinforced (6) again at the M groups of measuring points to obtain a first apparent resistivity sequence set of M areas to be reinforced (6); Step 303, perform data processing on the first apparent resistivity sequence set and the original apparent resistivity sequence set at the M groups of measuring points to obtain the effective reinforcement area and effective reinforcement width of the test borehole (12) at the M groups of measuring points; Step 304, calculate the average effective reinforcement width of the test borehole (12) within the area to be reinforced (6); Step 305, determine the number N of grouting holes (13) to be constructed within the area to be reinforced (6); Step 306, construct N grouting holes (13) along the length direction within the area to be reinforced (6), and perform grouting reinforcement in all N grouting holes (13) to complete the grouting reinforcement of the area to be reinforced (6).

2. A method for controlling water inrush from the coal seam floor according to claim 1, characterized in that: In Step 1, the process of determining the position of the area to be reinforced is as follows: Determine the horizons of the coal seam floor (2), water - resisting layer (3) and aquifer (4) below the coal mining face (1), and the area where the water - resisting layer (3) is located within the vertically upward - moving area (5) is the area to be reinforced (6).

3. A method for controlling water inrush from the coal seam floor according to claim 1, characterized in that: The measuring methods of the apparent resistivity of the area to be reinforced (6) at the M groups of measuring points in Step 202 are the same. When measuring the apparent resistivity of the area to be reinforced (6) at the m - th group of measuring points, it mainly includes the following steps: Step 2021: Place the transient electromagnetic instrument (11) at the first measurement point (9) of the m-th group of measurement points, such that the horizontal plane where the transmitting coil of the transient electromagnetic instrument (11) is located is perpendicularly arranged with respect to the vertical plane where the central axis of the transportation roadway (7) is located. Then, rotate the transmitting coil of the transient electromagnetic instrument (11) clockwise by 90°. During the rotation of the transmitting coil of the transient electromagnetic instrument (11), the transient electromagnetic instrument (11) measures the apparent resistivity of the area to be reinforced (6) at a set measurement interval, obtaining the original apparent resistivity of the area to be reinforced (6) at different angles at the first measurement point (9) of the m-th group of measurement points; where m is the measurement point number, 1 ≤ m ≤ M, and the measurement interval is 10° - 15°. Step 2022: Place the transient electromagnetic instrument (11) at the second measurement point (10) of the m-th group of measurement points, such that the horizontal plane where the transmitting coil of the transient electromagnetic instrument (11) is located is perpendicularly arranged with respect to the vertical plane where the central axis of the return airway (8) is located. Then, rotate the transmitting coil of the transient electromagnetic instrument (11) counterclockwise by 90°. During the rotation of the transmitting coil of the transient electromagnetic instrument (11), the transient electromagnetic instrument (11) measures the apparent resistivity of the area to be reinforced (6) at a set measurement interval, obtaining the original apparent resistivity of the area to be reinforced (6) at different angles at the second measurement point (10) of the m-th group of measurement points. Step 2023: Arrange the original apparent resistivity of the area to be reinforced (6) at different angles at the first measurement point (9) of the m-th group of measurement points obtained in Step 2021 and the original apparent resistivity of the area to be reinforced (6) at different angles at the second measurement point (10) of the m-th group of measurement points obtained in Step 2022 in the order of the measurement time to obtain the original apparent resistivity sequence set ρ of the area to be reinforced (6) at the m-th group of measurement points 0m , the original apparent resistivity sequence set ρ 0m includes A original apparent resistivities, and the a-th original apparent resistivity in the original apparent resistivity sequence set ρ 0m is denoted as ρ 0ma ; where A is a positive integer, a is the original apparent resistivity number, and 1 ≤ a ≤ A.

4. A method for controlling water inrush from the coal seam floor according to claim 3, characterized in that: In step 301, the test borehole (12) is arranged near the left end of the area to be reinforced (6), and the center of the test borehole (12) is located on the horizontal center line of the area to be reinforced (6). In step 302, the apparent resistivity of the area to be strengthened (6) at the m-th group of measurement points is measured to obtain the first apparent resistivity sequence set ρ of the area to be strengthened (6) at the m-th group of measurement points 1m , the first apparent resistivity sequence set ρ 1m includes A first apparent resistivities, and the a-th first apparent resistivity in the first apparent resistivity sequence set ρ 1m is denoted as ρ 1ma ; In step 303, the data processing methods for the first apparent resistivity sequence set and the original apparent resistivity sequence set at M groups of measurement points are the same. When processing the first apparent resistivity sequence set ρ 1m and the original apparent resistivity sequence set ρ 0m at the m-th group of measurement points, the main steps are as follows: Step 3031: One-to-one match the A first apparent resistivity values in the first apparent resistivity sequence set ρ 1m with the A original apparent resistivity values in the original apparent resistivity sequence set ρ 0m , and calculate the increase amplitudes of the A first apparent resistivity values at the m-th group of measurement points respectively; among them, the calculation methods of the increase amplitudes of the A first apparent resistivity values are the same. When calculating the increase amplitude of the a-th first apparent resistivity value, use the formula to calculate the increase amplitude Z 1a of the a-th first apparent resistivity value; Step 3032: Determine the effective reinforcement area of the test borehole (12) at the mth group of measuring points according to the increase amplitude of the A first apparent resistivity values. The basis for dividing the effective reinforcement area of the test borehole (12) is as follows: when the increase amplitude Z 1ma of the ath first apparent resistivity ρ 1a ≥ 10%, the area corresponding to the ath first apparent resistivity is located within the effective reinforcement area of the test borehole (12); Step 3033, measure the average width of the effective reinforcement area of the test borehole (12) at the m-th group of measuring points as the effective reinforcement width b of the test borehole (12) at the m-th group of measuring points 1m ; In step 304, according to the formula calculate the average effective reinforcement width of the test boreholes (12) in the area to be reinforced (6) In step 305, according to the formula determine the number of grouting holes (13) to be constructed in the area to be strengthened (6); where represents rounding up, and B1 is the maximum width of the area to be strengthened (6). In step 306, the structure of the grouting holes (13) is the same as that of the test boreholes (12). The centers of the N grouting holes (13) are all on the same horizontal plane as the center of the test borehole (12), and the hole spacing between two adjacent grouting holes (13) among the N grouting holes (13) is k.

5. A method for controlling water inrush from the coal seam floor according to claim 4, characterized in that: In step four, to determine the effective reinforcement area within the area to be reinforced after grouting reinforcement, the specific process is as follows: Step 401: According to the method described in step 302, measure the apparent resistivity of the area to be strengthened (6) again at M groups of measuring points, and obtain a second set of apparent resistivity sequences of M areas to be strengthened (6); among them, measure the apparent resistivity of the area to be strengthened (6) at the m-th group of measuring points, and obtain a second set of apparent resistivity sequences ρ of the area to be strengthened (6) at the m-th group of measuring points 2m , the second set of apparent resistivity sequences ρ 2m includes A second apparent resistivities, and the a-th second apparent resistivity in the second set of apparent resistivity sequences ρ 2m is denoted as ρ 2ma ; Step 402: According to the method described in step 303, perform data processing on the second apparent resistivity sequence set and the original apparent resistivity sequence set at the M groups of measurement points to determine the effective reinforcement areas of the N grouting holes (13) at the M groups of measurement points.

6. A method for controlling water inrush from the coal seam floor according to claim 5, characterized in that: In step five, to judge the water inrush risk of the area to be reinforced based on the effective reinforcement area within the area to be reinforced after grouting reinforcement, the specific process is as follows: When there is no connection between the effective reinforcement areas of any two adjacent grouting holes (13) at a certain group of measurement points among the M groups of measurement points, the area to be reinforced (6) has a water inrush risk, and step six is executed. When the effective reinforcement areas of any two adjacent grouting holes (13) at each group of measurement points among the M groups of measurement points are all connected, the area to be reinforced (6) has no water inrush risk, and step seven is executed.

7. A method for controlling water inrush from the coal seam floor according to claim 6, characterized in that: In step six, supplementary grouting reinforcement is carried out on the area to be reinforced, mainly including the following steps: Construct supplementary grouting holes between any two adjacent grouting holes (13) where the effective reinforcement areas are not connected, and perform supplementary grouting in the supplementary grouting holes to connect the effective reinforcement areas of any two adjacent grouting holes (13) at the M groups of measurement points.

8. A method for controlling water inrush from the coal seam floor according to claim 4, characterized in that: In step 301, both the starting position and the ending position of the test borehole (12) are located in front of the starting cut of the working face. The starting position of the test borehole (12) is determined by the width of the coal mining face (1). The distance L1 between the starting position of the test borehole (12) and the starting cut of the working face is L1 = 2B0 + L0, where B0 is the width of the coal mining face (1), and L0 is the distance between the ending position of the test borehole (12) and the starting cut of the working face. The value range of L0 is 20m to 40m.

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