Coal seam roof weakly cemented sandstone water control method

Abstract

The invention discloses a coal seam roof weakly-cemented sandstone water prevention and control method. The method is specifically implemented according to the following steps: step 1, determining division of a water-bearing stratum of a to-be-treated area and a groundwater supply direction; 2, determining a main water-filling and water-containing layer and a secondary water-filling and water-containing layer of the working face according to the division condition of the water-containing layers; 3, a layered and partitioned treatment method is adopted for the main water-filling and water-containing layer and the secondary water-filling and water-containing layer; and 4, the treatment effect is checked. According to the coal seam roof weakly-cemented sandstone water prevention and control method, the problems that residual dynamic make-up water of the aquifer weakens a weakly-cemented roof rock stratum and drainage of multiple aquifers is insufficient are solved.

Description

Technical Field

[0001] The invention belongs to the technical field of mine roof water hazard prevention and control methods, and relates to a coal seam roof weakly cemented sandstone water prevention and control method. Background Art

[0002] Generally, the coal seam roof rock has a weak degree of cementation and poor mechanical properties. After being disturbed by coal seam mining, the weakly cemented rock layer interacts with the residual roof sandstone water after roof drainage, and it is easy to form a mud-sand-water mixture that breaks into the mining space, causing disasters and accidents. The prevention and control of such disasters and accidents is difficult because the current conventional roof sandstone water prevention and control measures have the following deficiencies and defects in the prevention and control of weakly cemented sandstone water in the coal seam roof: ① The roof sandstone water is mainly porous sandstone aquifers, and the mechanical properties of the rock formation cannot be transformed by grouting; ② The drainage of sandstone water in the working face roof can effectively drain the static reserves of the aquifer, but cannot solve the weakening effect of the residual dynamic recharge water in the aquifer on the weakly cemented roof rock layer; ③ The working face roof is generally composed of multiple aquifers, and the water head heights of each aquifer are different. When mixed drainage is used, the aquifers affect each other and the maximum drainage effect cannot be achieved.

[0003] Therefore, in order to solve the shortcomings and defects of the current conventional roof sandstone water control measures for the weakly cemented sandstone water control in the coal seam roof, it is necessary to study a method for the weakly cemented sandstone water control in the coal seam roof. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preventing and controlling water in weakly cemented sandstone on the roof of a coal seam, which solves the problem of weakening of weakly cemented roof rock layers by residual dynamic replenishment water of aquifers and insufficient drainage of multiple aquifers.

[0005] The technical solution adopted by the present invention is a method for preventing and controlling water in weakly cemented sandstone of coal seam roof, which is specifically implemented according to the following steps:

[0006] Step 1: Determine the division of aquifers and groundwater recharge direction in the area to be treated;

[0007] Step 2, determining the main water-filled aquifer and the secondary water-filled aquifer of the working face according to the division of the aquifer;

[0008] Step 3: adopting a layered and zoned management approach for the primary and secondary aquifers;

[0009] Step 4: Test the effectiveness of the treatment.

[0010] Furthermore, step 1 is specifically as follows: according to the geological and hydrogeological conditions of the mine, the division of the aquifer and the direction of groundwater recharge are determined.

[0011] Furthermore, the aquifer is the aquifer within the range of the water-conducting fracture zone after mining.

[0012] Furthermore, the groundwater recharge direction in step 1 is determined by drawing water level line diagrams of each aquifer based on the dynamic monitoring data of the water level of each aquifer during the mine production process.

[0013] Furthermore, 2 is specifically as follows: draw contour maps of aquifer thickness and stratigraphic profiles parallel to the water recharge direction of the aquifer, analyze the plane connectivity of the sandstone aquifer, and classify aquifers with a thickness greater than 20 m in the plane, continuous distribution of aquifers in the profile, and medium or above water richness as main water-replenishing aquifers;

[0014] Aquifers with a thickness of less than or equal to 20m in plane, discontinuous distribution of aquifers in profile, weak water-richness, and mainly static reserves are classified as secondary water-replenishing aquifers.

[0015] Furthermore, the stratified management in step 3 refers to the separate drainage of aquifer water from the primary aquifer and the secondary aquifer;

[0016] Zoning management is to arrange drainage projects in different areas of the main water-filled aquifers, that is, the main water-filled aquifers are arranged with regional drainage projects on the periphery of the working face according to the groundwater recharge direction, perpendicular to the groundwater recharge direction, and the excavation layout;

[0017] Local drainage projects are arranged at the working face for secondary water-bearing aquifers.

[0018] Furthermore, in step 3, the regional drainage project for the main water-filled aquifer is specifically arranged as follows:

[0019] Regional drainage of the main water-filled aquifers Drilling to drain the main water-filled aquifers and casing to seal off the secondary water-filled aquifer sections;

[0020] The local drainage project for the secondary water-filled aquifer is as follows:

[0021] Drain the secondary aquifer locally by drilling holes to drain the secondary aquifer water and seal the primary aquifer water with casing.

[0022] Furthermore, the number of drainage boreholes n when draining water from the main water-filled aquifer and the secondary water-filled aquifer in step 3 is calculated according to the following formula:

[0023]

[0024] Among them, Q is the water inflow of the primary or secondary aquifer, and q is the water inflow of the drainage borehole.

[0025] Furthermore, step 4 is specifically as follows:

[0026] Inspection holes are arranged on the working face. The inspection holes are arranged in groups. The number of inspection holes is 5% to 10% of the number of drainage holes. Two inspection holes in each group are used to verify the main water-filled aquifer and the secondary water-filled aquifer respectively. After the drilling construction is completed, the water inflow and water head height of the inspection holes are measured. The water inflow of the drilling holes is less than 0.1m 3 / h, the water head height is lower than the bottom of the aquifer.

[0027] Furthermore, in step 2, the water-richness being medium or above means that the water-richness q>0.1L / s·m, and the water-richness being weak means that the water-richness q≤0.1L / s·m.

[0028] The beneficial effects of the present invention are:

[0029] The present invention aims to solve the problem that the interaction between the weakly cemented rock layer on the roof and the residual roof sandstone water during coalfield mining causes the mud-sand-water mixture to burst into the post-mining space and form disaster accidents. Through the analysis and research on the water-richness, planar distribution characteristics and recharge conditions of the weakly cemented sandstone aquifer on the roof of the coal seam, a new method of layered and zoned prevention and control is formulated, which solves the problem of the weakening of the weakly cemented roof rock layer by the residual dynamic recharge water of the weakly cemented sandstone water on the roof of the coal seam and the insufficient drainage of multiple aquifers caused by the current conventional roof sandstone water prevention and control measures. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a flow chart of the method for preventing and controlling water in weakly cemented sandstone of coal seam roof of the present invention;

[0031] Figure 2 It is a cross-sectional schematic diagram of the method for preventing and controlling water in weakly cemented sandstone of the coal seam roof according to the present invention;

[0032] Figure 3 It is a schematic plan view of the method for preventing and controlling water in weakly cemented sandstone of the coal seam roof according to the present invention. DETAILED DESCRIPTION

[0033] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0034] Example 1

[0035] The method for preventing and controlling water in weakly cemented sandstone of coal seam roof of the present invention has the following process: Figure 1 As shown, the specific steps are as follows:

[0036] Step 1: Determine the division of aquifers and the direction of groundwater recharge according to the geological and hydrogeological conditions of the mine, wherein the aquifer is the aquifer within the scope of the water-conducting fracture zone after the mine is mined; the groundwater recharge direction is determined by drawing a water level line diagram of each aquifer based on the dynamic monitoring data of the water level of each aquifer during the mine production process;

[0037] Step 2, such as Figure 2As shown in the figure, the main water-filled aquifer and the secondary water-filled aquifer of the working face are determined according to the division of aquifers, the aquifer thickness contour map and the stratigraphic profile parallel to the water recharge direction of the aquifer are drawn, the plane connectivity of the sandstone aquifer is analyzed, and the aquifers with a thickness greater than 20m on the plane, continuous distribution of aquifers on the profile, and medium or above water richness (q>0.1L / s·m) are divided as the main water-filled aquifers;

[0038] Aquifers with a thickness of less than or equal to 20m in plane, discontinuous distribution in profile, weak water-richness (q≤0.1L / s·m), and mainly static storage are classified as secondary recharge aquifers.

[0039] Step 3: adopting a stratified and zoned management method for the main water-filled aquifer and the secondary water-filled aquifer; wherein stratified management refers to draining the main water-filled aquifer and the secondary water-filled aquifer separately; Figure 3 As shown, zoning management is to arrange drainage projects in different areas of the main water-filled aquifers, that is, regional drainage projects are arranged on the periphery of the working face for the main water-filled aquifers according to the groundwater recharge direction, perpendicular to the groundwater recharge direction and the mining layout; local drainage projects are arranged on the working face for the secondary water-filled aquifers.

[0040] Among them, the regional drainage project for the main water-bearing aquifer is specifically as follows:

[0041] To improve drainage efficiency, regional drainage drilling is carried out for the main water-filled aquifer to drain the water from the main water-filled aquifer and casing is used to seal the secondary water-filled aquifer section;

[0042] The local drainage project for the secondary water-filled aquifer is as follows:

[0043] In order to avoid the different water head heights of each aquifer affecting the drainage effect, local drainage drilling is carried out in the secondary water-filled aquifer to drain the water of the secondary water-filled aquifer and casing is used to seal the water of the main water-filled aquifer.

[0044] Step 4 is as follows:

[0045] Inspection holes are arranged on the working face in groups. The number of inspection holes is 5% to 10% of the number of drainage holes. Two inspection holes in each group are used to verify the main water-filled aquifer and the secondary water-filled aquifer respectively.

[0046] Example 2

[0047] Based on Example 1, the number of drainage boreholes n when draining water from the main water-filled aquifer and the secondary water-filled aquifer is calculated according to the following formula:

[0048]

[0049] Among them, Q is the water inflow of the primary or secondary aquifer, and q is the water inflow of the drainage borehole.

[0050] Regional drainage boreholes only drain water from the main water-filled aquifer. To improve drainage efficiency, casing is used to seal the secondary water-filled aquifer section. Local drainage boreholes only drain water from the secondary water-filled aquifer. To avoid the different head heights of each aquifer affecting the drainage effect, casing is used to seal the main water-filled aquifer.

[0051] Example 3

[0052] In a typical coal mine mining Jurassic coal seam, the mechanical strength of the rock test items in the roof and floor sections is low, the saturated compressive strength of most rock layers Rc < 5MPa, the softening coefficient Ka < 0.77, the rock hardness coefficient f = 2 ~ 5, and the roof and floor of each coal seam are mostly extremely soft rocks with layered structures. The internal cohesion of the roof rock is small, the interlayer bonding force is weak, and the sandstone is easy to soften and disintegrate when it encounters water. In order to eliminate the disaster problem of mud, sand and water mixture bursting into the mining space caused by the interaction between the weakly cemented rock layer of the roof and the residual roof sandstone water during coal seam mining.

[0053] On the basis of Example 2, the control method of the present invention is adopted to carry out layered and zoned control, as follows:

[0054] Step 1: According to the geological and hydrogeological conditions of the mine, it is determined that two aquifers are developed in the water-conducting fracture zone of the coal seam. The thickness of aquifer I is 28.5 to 86.3 m, with an average of 63 m, and its water-richness is weak to medium; the thickness of aquifer II is 0 to 36.5 m, with an average of 10.8 m, and its water-richness is weak.

[0055] Step 2: Draw an iso-water level map based on the monitoring data of 7 water level long-holes in the well field aquifer I, and determine that the water recharge direction of the aquifer is in the northeast direction. Draw an iso-water level map based on the monitoring data of 5 water level long-holes in the aquifer II, and determine that the water recharge direction of the aquifer is in the northeast direction.

[0056] Step 3: Draw linear and cross-sectional diagrams of aquifer thickness based on the well field exploration drilling data, analyze the spatial distribution characteristics and connectivity of the sandstone aquifer, and determine that aquifer I has a large aquifer thickness, good sandstone connectivity, and weak to medium water-richness, and is determined to be the main water-filled aquifer. Aquifer 2 has a small aquifer thickness, poor sandstone connectivity, and weak water-richness, and is determined to be a secondary water-filled aquifer.

[0057] Step 4: Arrange the drainage project of aquifer I area in the northeast direction of the working face, and arrange the local drainage project of aquifer 2 in the working face drift.

[0058] Step 5: The drainage volume of the drainage project in the aquifer I area is expected to be 352m 3 / h, the single hole drainage volume is expected to be 15m3 / h, 31 drainage boreholes were arranged, and two sections of aquifer were sealed with casing; the local drainage volume of aquifer 2 was expected to be 150m 3 / h, the single hole drainage volume is expected to be 10m 3 / h, arranged 20 drainage holes, and used casing to seal the aquifer section I.

[0059] Step 6: After the drainage project was completed, two verification holes for aquifers I and II were arranged on the working face, and the water inflow of the boreholes was less than 0.1m 3 / h, the water head height in the borehole is lower than the bottom plate of the aquifer, achieving the purpose of treatment.

Claims

1. A method for preventing and controlling water in weakly cemented sandstone at the roof of a coal seam, characterized in that: The specific steps are as follows: Step 1: Determine the division of aquifers and groundwater recharge direction in the area to be treated; Step 2, determining the main water-filled aquifer and the secondary water-filled aquifer of the working face according to the division of the aquifer; Step 3: adopting a layered and zoned management approach for the primary and secondary aquifers; Step 4: Test the effectiveness of the treatment.

2. The method for preventing and controlling water in weakly cemented sandstone at the roof of a coal seam according to claim 1, characterized in that: The step 1 specifically includes: determining the division of aquifers and the direction of groundwater recharge according to the geological and hydrogeological conditions of the mine; The aquifer is the aquifer within the range of the water-conducting fracture zone after mining.

3. The method for preventing and controlling water in weakly cemented sandstone at the roof of a coal seam according to claim 2, characterized in that: In the step 1, the groundwater recharge direction is determined by drawing a water level line diagram of each aquifer based on the dynamic monitoring data of the water level of each aquifer during the mine production process.

4. The method for preventing and controlling water in weakly cemented sandstone at the roof of a coal seam according to claim 3, characterized in that: The above 2 is specifically as follows: draw aquifer thickness contour map and stratigraphic profile parallel to the water recharge direction of the aquifer, analyze the plane connectivity of the sandstone aquifer, and classify aquifers with a thickness of more than 20m on the plane, continuous distribution of aquifers on the profile, and medium or above water richness as main water-replenishing aquifers; Aquifers with a thickness of less than or equal to 20m in plane, discontinuous distribution of aquifers in profile, weak water-richness, and mainly static reserves are classified as secondary water-replenishing aquifers.

5. The method for preventing and controlling water in weakly cemented sandstone at the roof of a coal seam according to claim 4, characterized in that: The stratified management in step 3 refers to draining water from the main aquifer and the secondary aquifer respectively; Zoning management is to arrange drainage projects in different areas of the main water-filled aquifers, that is, the main water-filled aquifers are arranged with regional drainage projects on the periphery of the working face according to the groundwater recharge direction, perpendicular to the groundwater recharge direction, and the excavation layout; Local drainage projects are arranged at the working face for secondary water-bearing aquifers.

6. The method for preventing and controlling water in weakly cemented sandstone at the roof of a coal seam according to claim 5, characterized in that: In step 3, the regional drainage project for the main water-filled aquifer is specifically arranged as follows: Regional drainage of the main water-filled aquifers Drilling to drain the main water-filled aquifers and casing to seal off the secondary water-filled aquifer sections; The local drainage project for the secondary water-filled aquifer is as follows: Drain the secondary aquifer locally by drilling holes to drain the secondary aquifer water and seal the primary aquifer water with casing.

7. The method for preventing and controlling water in weakly cemented sandstone at the roof of a coal seam according to claim 6, characterized in that: The number of drainage boreholes n for draining water from the main water-filled aquifer and the secondary water-filled aquifer in step 3 is calculated according to the following formula: Among them, Q is the water inflow of the primary or secondary aquifer, and q is the water inflow of the drainage borehole.

8. The method for preventing and controlling water in weakly cemented sandstone at the roof of a coal seam according to claim 7, characterized in that: The step 4 is specifically as follows: Inspection holes are arranged on the working face. The inspection holes are arranged in groups. The number of inspection holes is 5% to 10% of the number of drainage holes. Two inspection holes in each group are used to verify the main water-filled aquifer and the secondary water-filled aquifer respectively. After the drilling construction is completed, the water inflow and water head height of the inspection holes are measured. The water inflow of the drilling holes is less than 0.1m 3 / h, the water head height is lower than the bottom of the aquifer.

9. The method for preventing and controlling water in weakly cemented sandstone at the roof of a coal seam according to claim 7, characterized in that: In the step 2, the water-richness is medium or above, which means that the water-richness q is greater than 0.1 L / s·m, and the water-richness is weak, which means that the water-richness q is less than or equal to 0.1 L / s·m.

Images