Subsidence control method based on dynamic observation of stratigraphic movement

Abstract

This invention belongs to the field of surveying and subsidence control, specifically relating to a subsidence control method based on dynamic observation of strata movement. This invention obtains the dynamic movement patterns of strata by setting up surface and rock strata monitoring stations. Based on these patterns and the geological conditions of coal seam mining, it provides options for post-mining goaf grouting and backfilling, bottom coal mining, combined post-mining grouting and backfilling with bottom coal mining, and combined anchored shaft and underground partial backfilling mining. These options are particularly suitable for small-scale or individual building / structure mining, offering low cost and high efficiency. This invention creatively applies the dynamic movement patterns of strata to subsidence control, providing a reference for related research and stimulating further discussion.

Description

Technical Field

[0001] This invention belongs to the field of surveying and subsidence control, and specifically relates to a subsidence control method based on dynamic observation of strata movement. Background Technology

[0002] Setting up monitoring stations on the surface and obtaining subsidence data can be used to assess the damage to the strata after coal mining. However, currently, most of the data used is the final subsidence observation data, and there is a lack of utilization of dynamic subsidence observation data. Further exploration of subsidence patterns based on subsidence data, especially dynamic subsidence data, to guide coal mining has been a long-standing area of ​​exploration and practice in the industry.

[0003] Subsidence control methods in coal mining mainly include pillar-based skip mining and backfilling mining. Backfilling mining is suitable for mining under large-scale buildings or relatively large structures such as dams, while pillar-based skip mining is suitable for mining under small-scale or individual buildings or structures. However, pillar-based skip mining results in the loss of a large amount of coal resources and the scope of pillar-based mining is relatively conservative. Relocating buildings or structures takes a relatively long time. Therefore, how to conduct small-scale or individual mining under buildings or structures with the least loss or investment has been a problem that the industry has been hoping to solve. Summary of the Invention

[0004] To address the technical challenge of balancing economic efficiency and construction efficiency in coal mining under small-scale or individual buildings and structures, this invention utilizes monitoring stations to observe and acquire the dynamic movement patterns of strata. Based on these patterns and the geological conditions of coal seam mining, it provides options for post-mining goaf grouting and backfilling, bottom coal retention mining, and combined mining with anchored shafts and localized underground backfilling. Specifically, the subsidence control method based on dynamic strata movement observation of this invention includes the following steps:

[0005] 1. Rock movement observation wells shall be set up in the protected areas corresponding to the test working face and the target working face. Rock movement observation wells shall be equipped with rock strata monitoring stations inside the top and surface monitoring stations at the top surface.

[0006] 2. The test working face was mined, and dynamic moving observations were carried out at the surface monitoring station and the rock strata monitoring station at the same time;

[0007] The subsidence value A2 of the old roof was determined after the working face had just passed the rock movement observation hole and the old roof had just collapsed, combined with the original rock thickness h of the collapse zone. s The mining height M of the test working face S Determine the initial breccia coefficient k of the caving zone;

[0008] Determine the dynamic surface subsidence value A(x) observed by surface monitoring stations within the protected area as the working face advances. Then, calculate the dynamic surface subsidence coefficient α2(x) corresponding to different positions of the working face advancement. This coefficient is the sum of the dynamic surface subsidence value A(x) observed by surface monitoring stations within the protected area and the mining height M of the experimental working face. S The ratio, where x refers to the distance the working face has advanced since the cut.

[0009] 3. Determine the maximum subsidence value B that the protected area above the target working face can withstand; based on the mining height M of the target working face. M Thickness h of the original rock in the caving zone m The initial fragmentation coefficient k of the collapse zone is used to estimate the subsidence value B2 of the old roof after the target working face collapses, and compare it with the maximum subsidence value B that the protected area can withstand.

[0010] If B2 is less than B, then for the target working face mining range that affects the protected area, grouting boreholes are constructed above it. When the target working face has just pushed past a certain grouting borehole and the old roof below the grouting borehole has just collapsed, cementing material is injected into the goaf from the grouting borehole.

[0011] 4. If B2 is greater than B, in addition to injecting cementing material into the goaf as in step 3, it is also necessary to reduce the mining height by leaving a bottom.

[0012] V. If the solution in step four still cannot control the surface subsidence of the protected area to within the maximum subsidence value B that the protected area can withstand, then a combined mining scheme of anchored shaft and underground partial backfilling will be adopted, as follows: In the protected area, anchored shafts will be constructed from the surface and cementing materials will be injected to form anchored piles. At the same time, directly below the protected area, after the target working face is mined, steel ladle support columns will be used to support the direct top. Under the support of the steel ladle support columns, waste gangue generated during mining will be discharged into the goaf area, and cementing materials will be injected into the accumulated waste gangue to form a gangue cemented backfill body.

[0013] VI. If the surface subsidence of the protected area cannot be controlled within the maximum subsidence value B that the protected area can withstand by adopting the scheme in step five, in addition to implementing the scheme of combined mining of anchor shafts and local backfilling in the protected area in step five, it is also necessary to carry out backfilling in the well within a certain range outside the protected area.

[0014] Preferably, in step one, the rock movement observation holes include at least three located on both sides of the protected area and in the middle of the protected area in the direction of the working face advance.

[0015] Preferably, in step two, based on the observation results, the maximum surface subsidence value A1 after the surface stabilizes following the mining of the working face is determined, and this value is compared with the mining height M of the test working face. S The ratio of α1 to α2 is used as the final subsidence coefficient α1 of the land surface.

[0016] Preferably, in step four, the method of reducing the mining height by leaving a bottom is as follows: before the target working face advances to the mining range of the target working face affecting the protected area, slope mining is carried out, so that when the target working face advances to the boundary of the mining range of the target working face affecting the protected area, the mining height is reduced to M. N When the target working face advances to the other boundary of the target working face mining area affecting the protected area, the slope is lowered and the mining height is gradually restored to M. M .

[0017] Preferably, in step four, the reduction in sampling height does not exceed 300 mm.

[0018] Preferably, in step four, the reduced sampling height M N It should be ensured that it falls within the mining height range applicable to the original hydraulic support.

[0019] Preferably, in step five, the sum of the subsidence coefficients at the two boundaries of the protection zone in the direction of face advance is determined when the working face has just been mined back to the boundary of the protection zone, and this sum is multiplied by the mining height M. M The product is taken as the maximum subsidence value B3 of the protected area. The maximum subsidence value B3 of the protected area is less than the maximum subsidence value B that the protected area can withstand.

[0020] Preferably, in step five, the construction scope of the anchoring shaft is multiple rock strata anchoring holes set in layers along the anchoring shaft from the ground surface to above the old top.

[0021] Preferably, in step five, the steel-clad support column is a cylinder with a steel outer circumference and a reinforced concrete inner layer.

[0022] Preferably, in step six, the scheme of carrying out underground filling within a certain range outside the protected area is the same as the scheme of carrying out underground filling directly below the protected area in step five.

[0023] Preferably, the method for determining the certain range outside the protection zone is as follows: when the working face advances to a certain range outside the protection zone, the sum of the subsidence coefficients at the two boundaries of the protection zone in the direction of working face advancement is added to the mining height M. M The product of these values ​​is taken as the maximum subsidence value B4 of the protected area. The maximum subsidence value B4 of the protected area is equal to the maximum subsidence value B that the protected area can withstand.

[0024] Preferably, when the target working face has a small mining height and a small final surface subsidence coefficient α1, the protected area is protected only by reducing the mining height. The mining height reduction method is the same as the mining height reduction method in step four, and the reduction value of the mining height does not exceed 300mm.

[0025] Beneficial Technical Effects: This invention obtains the dynamic movement patterns of strata by setting up surface and rock strata monitoring stations. Based on these patterns and the geological conditions of coal seam mining, it provides options for post-mining goaf grouting and backfilling, bottom coal mining, combined post-mining grouting and backfilling with bottom coal mining, and combined anchored shaft and underground partial backfilling mining. These options are particularly suitable for coal mining under small-scale or individual buildings and structures, offering low cost and high efficiency. This invention creatively applies the dynamic movement patterns of strata to subsidence control, providing a reference for related research and stimulating further discussion. Attached Figure Description

[0026] Figure 1 This is a schematic cross-sectional view of the station layout of the present invention;

[0027] Figure 2 This is a schematic cross-sectional view of the post-harvest grouting and filling arrangement of the present invention;

[0028] Figure 3 This is a schematic cross-sectional view of the combined mining layout of post-mining grouting and bottom coal retention according to the present invention;

[0029] Figure 4 This is a schematic cross-sectional view of the combined mining layout of anchored vertical shaft and underground partial backfilling according to the present invention;

[0030] Figure 5 This is a schematic cross-sectional view of the bottom coal mining layout of the present invention;

[0031] In the figure, the loose layer is 1, the rock layer is 2, the old roof is 21, the coal seam is 3, the bottom coal is 31, the rock movement observation hole is 4, the surface station is 41, the rock layer station is 42, the grouting borehole is 5, the goaf is 6, the anchored shaft is 7, the steel ladle support column is 81, and the gangue cemented filling body is 82. Detailed Implementation

[0032] The invention will now be further described with reference to the accompanying drawings.

[0033] The subsidence control method based on dynamic observation of strata movement of the present invention includes the following steps:

[0034] 1. Select a test working face. The geological mining conditions of the test working face are basically the same as those of the target working face. There is a protected area (hereinafter referred to as the protected area) on the surface above the target working face consisting of a small area or individual buildings or structures. Due to the long migration cycle of buildings or structures and the tight succession of coal mining faces, the target working face needs to adopt a subsidence reduction mining scheme in order to protect the protected area while achieving normal mining of the target working face.

[0035] like Figure 1As shown, multiple rock movement observation holes 4 are set up in the protected areas corresponding to the test working face and the target working face. The multiple rock movement observation holes 4 include at least three located on both sides of the protected area and in the middle of the protected area in the direction of working face advancement. The multiple rock movement observation holes 4 are located near the middle of the working face in the width direction. The rock movement observation holes 4 are constructed from the surface through the loose layer 1 into the rock layer 2, and are constructed to the old roof 21 in the rock layer 2. A rock layer monitoring station 42 is set up in the old roof 21, and a surface monitoring station 41 is set up at the surface of the top of the rock movement observation holes 4. The rock layer monitoring station 42 is used to observe the dynamic movement (mainly subsidence) of the old roof 21 during the working face mining process, and the surface monitoring station 41 is used to observe the dynamic movement (mainly subsidence) of the surface.

[0036] 2. During the trial mining, dynamic mobile observations were conducted on surface station 41 and rock stratum station 42. The observation cycle was one week, that is, observations were conducted once every week. When the subsidence rate of surface station 41 or rock stratum station 42 was greater than 2 mm / day, the observation cycle was set to 1-2 days, that is, observations were conducted once every 1-2 days. When the average subsidence rate of surface station 41 was less than 0.2 mm / day and the cumulative subsidence was less than 5 mm for a continuous month, the observation of surface station 41 was stopped.

[0037] Based on the observation results, the maximum surface subsidence value A1 was determined after the working face was mined and the surface stabilized (the subsidence velocity at surface monitoring station 41 was less than 0.2 mm / day and the cumulative subsidence was less than 5 mm for one consecutive month). The relationship between A1 and the mining height M of the test working face was then calculated. S The ratio of α1 to α2 is used as the final subsidence coefficient of the land surface.

[0038] The subsidence value A2 of the old roof 21 was determined after the working face had just pushed past the rock movement observation hole 4 and the old roof 21 had just collapsed. Based on the original rock thickness h of the collapse zone... s The initial breccia coefficient k of the caving zone is obtained by the formula (k-1)*h. s =M S -A2,(k-1)*h s This refers to the increased thickness of the caving zone compared to the original caving rock after the initial bulging.

[0039] The dynamic surface subsidence value A(x) observed by 41 surface monitoring stations within the protected area was determined as the working face advanced. The dynamic surface subsidence coefficient α2(x) corresponding to different positions of the working face was then calculated. This coefficient is the sum of the dynamic surface subsidence value A(x) and the mining height M of the experimental working face. S The ratio, where x refers to the distance the working face advances from the cut.

[0040] 3. Determine the maximum subsidence value B that the protected area above the target working face can withstand; based on the mining height M of the target working face. M Initial thickness h of the collapse zone mBased on the initial calving coefficient k of the caving zone, calculate the subsidence value B2 of the target working face at the moment the old roof 21 collapsed, where B2 = M. M -(k-1)*h m And compare it with the maximum subsidence value B that the protected area can withstand;

[0041] like Figure 2 As shown, if the subsidence value B2 of the old roof when the target working face just collapsed is less than the maximum subsidence value B that the protected area can withstand (a certain safety factor can be taken, such as less than 90% of the maximum subsidence value B that the protected area can withstand, the same applies below. Since taking the safety factor is a basic common sense in this field, the inventor will not elaborate on it here, but it should be understood that taking the safety factor is also within the scope of protection of this invention), then for the target working face mining range that affects the protected area, a grouting borehole 5 is constructed above it. When the target working face just pushes past a certain grouting borehole 5 and the old roof 21 below the grouting borehole 5 just collapses, cementing material is injected from the grouting borehole 5 into the goaf into the gap of the rock mass in the goaf collapse zone, controlling the old roof 21 to continue to sink, so that the subsidence value of the upper rock layer 2, loose layer 1 and down to the ground surface of the old roof 21 are all controlled at the subsidence value B2 of the old roof when it just collapsed.

[0042] IV. Figure 3 As shown, if the subsidence value B2 of the old roof after the target working face has just collapsed is greater than the maximum subsidence value B that the protected area can withstand, in addition to injecting cementing material into the goaf in step three, it is also necessary to reduce the mining height.

[0043] Specifically, for the target working face mining range that affects the protected area, the mining height will be adjusted from M... M Reduced to M N And above it, a grouting borehole 5 is constructed. When the target working face has just pushed past a certain grouting borehole 5 and the old roof 21 below the grouting borehole 5 has just collapsed, cementing material is injected from the grouting borehole 5 into the goaf into the gap of the rock mass in the goaf collapse zone, controlling the old roof 21 to continue to sink, so that the sinking value of the upper rock layer 2, loose layer 1 and the ground surface of the old roof 21 is controlled at the sinking value B2 of the old roof when it just collapsed.

[0044] The method for reducing the mining height is as follows: when the target working face advances to a distance of 10-15m from the mining range of the target working face in the affected protection zone, slope mining is initiated, so that the mining height is reduced to M when the target working face advances to the boundary of the mining range of the target working face in the affected protection zone. N When the target working face advances to the other boundary of the target working face mining area affecting the protected area, the slope is lowered and the mining height is gradually restored to M. M ;

[0045] The reduction in mining height shall not exceed 300 mm.

[0046] Among them, the reduced sampling height M N It should be ensured that the mining height falls within the applicable range of the original hydraulic support, and that the original hydraulic support can be used for mining at a height of M. N The mining work;

[0047] V. For example Figure 4 As shown, if the solution in step four still cannot control the surface subsidence of the protected area to within the maximum subsidence value B that the protected area can withstand, then a combined mining solution of anchored shafts and underground partial backfilling will be adopted.

[0048] The proposed combined anchored shaft and underground partial backfilling mining scheme is a modified version of previous research (CN114673540A, A Method for Controlling the Migration of Underground Strata in Mining Areas), as detailed below:

[0049] When the working face has just been mined back to the boundary of the protection zone, determine the sum of the subsidence coefficients at the two boundaries of the protection zone in the direction of working face advancement, and then add them to the mining height M. M The maximum subsidence value B3 of the protected area is taken as the maximum subsidence value B that the protected area can withstand. If the maximum subsidence value B3 of the protected area is less than the maximum subsidence value B that the protected area can withstand, then within the protected area, anchor shafts 7 are constructed from the ground surface. The construction range extends from the ground surface to above the old top 21, but does not pass through the old top 21. Multiple rock strata anchoring holes are set in layers along the anchor shafts. The hole-making method can be hydraulic cutting. Cementing material is injected into the anchor shafts to form several anchor piles within the protected area. The anchor piles are equivalent to several nails being constructed in the strata. They can reduce the disturbance of coal seam mining to the protected area. The mechanism of reducing disturbance is that the anchor piles can reduce the tensile damage of coal seam mining outside the protected area to the rock strata within the protected area and reduce the compressive deformation of the rock strata within the protected area caused by mining disturbance.

[0050] Meanwhile, directly below the protected area, after the target working face is mined, a steel ladle support column 81 is used to support the roof to prevent it from collapsing. The steel ladle support column 81 is a cylinder with a steel outer circumference and a reinforced concrete inner layer. Under the support of the steel ladle support column 81, the waste gangue generated during mining is discharged into the goaf area, and cementing material is injected into the accumulated waste gangue to form a gangue cemented filling body 82.

[0051] VI. For example Figure 4 As shown, if the solution in step five still cannot control the surface subsidence of the protected area within the maximum subsidence value B that the protected area can withstand, in addition to implementing the solution of anchoring the protected area shaft and local backfilling in step five, it is also necessary to carry out underground backfilling within a certain range outside the protected area; so that the surface subsidence of the protected area is controlled within the maximum subsidence value B that the protected area can withstand when mining coal seams outside the certain range outside the protected area.

[0052] Within a certain range outside the protected area, after the target working face is mined, a steel ladle support column 81 is used to support the roof directly to prevent the roof from collapsing. The steel ladle support column 81 is a cylinder with a steel outer circumference and a reinforced concrete inner layer. Under the support of the steel ladle support column 81, the waste gangue generated during mining is discharged into the goaf, and the accumulated waste gangue is filled with cementing material gangue cemented backfill body 82.

[0053] The method for determining a certain range outside the protection zone is as follows: when the working face advances to a certain range outside the protection zone, the sum of the subsidence coefficients at the two boundaries of the protection zone in the direction of working face advancement is multiplied by the mining height M. M The product of these values ​​is taken as the maximum subsidence value B4 of the protected area. The maximum subsidence value B4 of the protected area is equal to the maximum subsidence value B that the protected area can withstand.

[0054] VII. For example Figure 5 As shown, when the target working face has a small mining height and the final surface subsidence coefficient α1 is small, the protected area can be protected simply by reducing the mining height.

[0055] The method for reducing the mining height is as follows: when the target working face advances to a distance of 10-15m from the mining range of the target working face in the affected protection zone, slope mining is initiated, so that the mining height is reduced to M when the target working face advances to the boundary of the mining range of the target working face in the affected protection zone. N When the target working face advances to the other boundary of the target working face mining area affecting the protected area, the slope is lowered and the mining height is gradually restored to M. M M M Reduced to M N At that time, the maximum subsidence value of the protected area was M M α1 decreases to M N α1;

[0056] The reduction in mining height shall not exceed 300 mm.

[0057] Among them, the reduced sampling height M N It should be ensured that the mining height falls within the applicable range of the original hydraulic support, and that the original hydraulic support can be used for mining at a height of M. N The mining work.

Claims

1. A subsidence control method based on dynamic observation of stratigraphic movement, characterized in that, Includes the following steps:

1. Rock movement observation wells shall be set up in the protected areas corresponding to the test working face and the target working face. Rock movement observation wells shall be equipped with rock strata monitoring stations inside the top and surface monitoring stations at the top surface.

2. The test working face was mined, and dynamic moving observations were carried out at the surface monitoring station and the rock strata monitoring station at the same time; The subsidence value A2 of the old roof was determined after the working face had just passed the rock movement observation hole and the old roof had just collapsed, combined with the original rock thickness h of the collapse zone. s The mining height M of the test working face S The initial breccia coefficient k of the caving zone is obtained using the formula (k-1)*h. s =M S -A2,(k-1)*h s This refers to the increased thickness of the caving zone compared to the original caving rock after the initial bulging. Determine the dynamic surface subsidence value A(x) observed by surface monitoring stations within the protected area as the working face advances. Then, calculate the dynamic surface subsidence coefficient α2(x) corresponding to different positions of the working face advancement. This coefficient is the sum of the dynamic surface subsidence value A(x) observed by surface monitoring stations within the protected area and the mining height M of the experimental working face. S The ratio, where x refers to the distance the working face has advanced since the cut.

3. Determine the maximum subsidence value B that the protected area above the target working face can withstand; based on the mining height M of the target working face. M The initial fragmentation coefficient k of the caving zone is used to estimate the subsidence value B2 of the old roof after the target working face has just collapsed. B2 = M M -(k-1)*h s And compare it with the maximum subsidence value B that the protected area can withstand; If B2 is less than B, then for the target working face mining range that affects the protected area, grouting boreholes are constructed above it. When the target working face has just pushed past a certain grouting borehole and the old roof below the grouting borehole has just collapsed, cementing material is injected into the goaf from the grouting borehole.

4. If B2 is greater than B, in addition to injecting cementing material into the goaf as in step 3, it is also necessary to reduce the mining height by leaving a bottom. V. If the solution in step four still cannot control the surface subsidence of the protected area to within the maximum subsidence value B that the protected area can withstand, then a combined mining scheme of anchored shaft and underground partial backfilling will be adopted, as follows: In the protected area, anchored shafts will be constructed from the surface and cementing materials will be injected to form anchored piles. At the same time, directly below the protected area, after the target working face is mined, steel ladle support columns will be used to support the direct top. Under the support of the steel ladle support columns, waste gangue generated during mining will be discharged into the goaf area, and cementing materials will be injected into the accumulated waste gangue to form a gangue cemented backfill body. VI. If the surface subsidence of the protected area cannot be controlled within the maximum subsidence value B that the protected area can withstand by adopting the scheme in step five, in addition to implementing the scheme of combined mining with anchoring shafts and local backfilling in the protected area in step five, it is also necessary to carry out underground backfilling within a certain range outside the protected area; the method for determining the certain range outside the protected area is to sum the subsidence coefficients at the two boundaries of the protected area in the direction of working face advancement when the working face advances to the certain range outside the protected area, and then add this sum to the mining height M. M The product of these values ​​is taken as the maximum subsidence value B4 of the protected area. The maximum subsidence value B4 of the protected area is equal to the maximum subsidence value B that the protected area can withstand.

2. The subsidence control method based on dynamic observation of strata movement according to claim 1, characterized in that, In step one, the rock movement observation wells include at least three located on both sides of the protected area and in the middle of the protected area in the direction of the working face advance.

3. The subsidence control method based on dynamic observation of strata movement according to claim 1, characterized in that, In step two, based on the observation results, the maximum surface subsidence value A1 after the surface stabilizes following the mining of the working face is determined, and this value is compared with the mining height M of the test working face. S The ratio of α1 to α2 is used as the final subsidence coefficient α1 of the land surface.

4. The subsidence control method based on dynamic observation of strata movement according to claim 3, characterized in that, In step four, the method of reducing the mining height by leaving a bottom is as follows: before the target working face advances to the mining range of the target working face affecting the protected area, slope mining is carried out, so that when the target working face advances to the boundary of the mining range of the target working face affecting the protected area, the mining height is reduced to M. N When the target working face advances to the other boundary of the target working face mining area affecting the protected area, the slope is lowered and the mining height is gradually restored to M. M .

5. The subsidence control method based on dynamic observation of strata movement according to claim 4, characterized in that, In step four, the reduction in mining height shall not exceed 300 mm; the reduced mining height M N It should be ensured that it falls within the mining height range applicable to the original hydraulic support.

6. The subsidence control method based on dynamic observation of strata movement according to claim 1, characterized in that, When using step five, determine the sum of the subsidence coefficients at the two boundaries of the protection zone in the direction of face advance when the working face has just been mined back to the boundary of the protection zone, and then sum this sum with the mining height M. M The product is taken as the maximum subsidence value B3 of the protected area. The maximum subsidence value B3 of the protected area is less than the maximum subsidence value B that the protected area can withstand.

7. The subsidence control method based on dynamic observation of strata movement according to claim 1, characterized in that, In step five, the construction scope of the anchoring shaft is from the ground surface to the top of the old roof, and multiple rock strata anchoring holes are set in layers along the anchoring shaft; in step five, the steel-clad support column is a cylinder with a steel outer circumference and a reinforced concrete inner layer.

8. The subsidence control method based on dynamic observation of strata movement according to claim 1 or 7, characterized in that, In step six, the method of carrying out underground filling within a certain range outside the protected area is the same as the method of carrying out underground filling directly below the protected area in step five.

9. The subsidence control method based on dynamic observation of strata movement according to claim 4, characterized in that, When the target working face has a small mining height and a small final surface subsidence coefficient α1, the protected area is protected only by reducing the mining height. The mining height reduction method is the same as the mining height reduction method in step four, and the reduction value of the mining height shall not exceed 300mm.

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