A water control method for downward mining of a working face near an aquifer

Abstract

The present invention provides a water control method for downward mining of a working face near an aquifer. The water control method comprises the following steps: Step 1, determining the designed quantity of working faces and the replacement sequence of working faces; Step 2, constructing a water retaining curtain for the working faces affected by the aquifer; Step 3, constructing pumping boreholes into the aquifer within the water retaining curtain and conducting pumping, and simultaneously grouting into the aquifer; Step 4, conducting mining upwards from the first working face at the deepest part of the coal seam. After the mining of the first working face, detecting the water inflow of the next working face and promptly conducting water drainage work; Step 5, before mining the last working face, detecting the water inflow of the last working face and the adjacent roadways and conducting water drainage work; if the detected water inflow is large, supplementing grouting treatment within the range of the water retaining curtain. In this water control method, while achieving the effect of no water storage within the water retaining curtain, it also reduces the construction cost, improves the construction efficiency, and protects the ecological environment.

Description

Technical Field

[0001] The invention belongs to the technical field of safe coal mining, and particularly relates to a water control method for downward mining of a working face near an aquifer. Background Art

[0002] Water inrush refers to the phenomenon that a large amount of groundwater suddenly and concentratedly floods into mine roadways. Mine water inrush is one of the most threatening disasters in the process of coal mine production, causing heavy casualties and ranking first among the three major coal mine accidents in terms of economic losses. When the bedrock between the loose aquifer and the coal seam is thin and the distance between the loose aquifer and the coal seam is relatively close, water inrush accidents are extremely likely to occur during the coal mining process.

[0003] To ensure the safety of coal mining, the traditional method is to leave a certain distance of coal pillars between the coal seam and the loose aquifer and grout and reinforce the top of the coal seam; the above traditional method not only causes losses of coal resources, but also when grouting and reinforcing the top of the coal seam, the slurry escapes everywhere, resulting in a large amount of slurry waste, and the effectiveness of grouting and reinforcement cannot be guaranteed, increasing the construction cost.

[0004] Therefore, an improved technical solution is needed to address the deficiencies of the above existing technologies. Contents of the Invention

[0005] The purpose of the invention is to provide a water control method for downward mining of a working face near an aquifer to at least solve the above problems existing in the prior art.

[0006] To achieve the above purpose, the invention provides the following technical solutions:

[0007] A water control method for downward mining of a working face near an aquifer, the water control method comprising the following steps:

[0008] Step 1, determine the number of working face designs and the working face replacement sequence according to the distance relationship between the upper boundary of the coal seam and the aquifer and the water-resisting layer;

[0009] Step 2, construct a water-blocking curtain for the working face affected by the aquifer, and the water-blocking curtain is a pile-connected wall structure;

[0010] The water-blocking curtain extends from the ground to the water-resisting layer, and the water-blocking curtain covers the working face affected by the aquifer and the roadway near the working face in the vertical projection direction;

[0011] Step 3, construct pumping boreholes into the aquifer within the water-blocking curtain and pump water, and at the same time grout into the aquifer until there is no water left within the range of the water-blocking curtain and it is filled with grout;

[0012] Step 4: Mining is carried out upward from the first working face at the deepest part of the coal seam. After the mining of the first working face is completed, the water inflow of the next working face and the roadway near the working face is detected, and the water drainage work is carried out in a timely manner until the last working face closest to the aquifer is mined.

[0013] Step 5: Before mining the last working face, the water inflow of the last working face and the nearby roadway is detected, and the water drainage work is carried out; if the detected water inflow is large, supplementary grouting treatment is carried out within the range of the water retaining curtain until the detected water inflow reaches the standard, and then the mining operation of the last working face is carried out.

[0014] For the water control method for downward mining of the working face near the aquifer as described above, preferably, a diversion wall is arranged on the water retaining curtain facing the water flow direction of the aquifer, and the diversion wall has an inclination angle with the water flow direction of the aquifer.

[0015] For the water control method for downward mining of the working face near the aquifer as described above, preferably, the diversion wall is a herringbone wall, and the tip of the herringbone wall faces the water flow direction of the aquifer.

[0016] For the water control method for downward mining of the working face near the aquifer as described above, preferably, in the vertical projection direction, the herringbone wall is located on the front side of the front end of the working face affected by the aquifer.

[0017] For the water control method for downward mining of the working face near the aquifer as described above, preferably, the water retaining curtain further includes two transverse walls, and the two transverse walls are respectively connected to both sides of the herringbone wall.

[0018] For the water control method for downward mining of the working face near the aquifer as described above, preferably, the distance between the two transverse walls is greater than the width of the working face affected by the aquifer, and in the vertical projection direction, both transverse walls are located outside the left and right sides of the working face affected by the aquifer.

[0019] For the water control method for downward mining of the working face near the aquifer as described above, preferably, the water retaining curtain further includes a longitudinal wall, and the longitudinal wall is connected to the ends of the two transverse walls far from the herringbone wall.

[0020] For the water control method for downward mining of the working face near the aquifer as described above, preferably, in the vertical projection direction, the longitudinal wall is located on the rear side of the rear end of the working face affected by the aquifer.

[0021] For the water control method for downward mining of the working face near the aquifer as described above, preferably, in step 3, the pumping borehole extends into the upper-middle part of the aquifer, a steel casing is arranged inside the pumping borehole, and a filter screen is arranged at the bottom of the steel casing.

[0022] For the water control method of downward mining in the near-aquifer working face as described above, preferably, in step 3, grouting bolts are set to grout the aquifer, and the bottom end of the grouting bolt extends into the upper part of the water-resisting layer.

[0023] Beneficial effects:

[0024] In this water control method, the water-blocking curtain not only plays a role in water isolation, reducing the pumping volume, but also plays a role in preventing the escape of grouting liquid, further reducing the grouting volume. While pumping water, grouting is carried out, and the grouting liquid sinks to the bottom of the aquifer inside the water-blocking curtain, raising the water surface height inside the water-blocking curtain, making it more convenient for pumping operations. Moreover, the groundwater resources are protected, and the local ecological environment is protected. The water-blocking curtain, grouting operation and pumping operation cooperate with each other. While achieving the effect of no water storage inside the water-blocking curtain, it can greatly reduce the construction cost, improve the construction efficiency, and protect the ecological environment.

[0025] The water flow of the aquifer, through the guiding action of the herringbone wall, flows to both sides of the herringbone wall, avoiding the water flow directly scouring the herringbone wall vertically, ensuring that the herringbone wall receives the smallest possible water flow impact force, ensuring that the herringbone wall can always effectively play its guiding role, and preventing the water flow from seeping into the inside of the water-blocking curtain wall. Description of the drawings

[0026] The specification drawings forming a part of the present application are used to provide a further understanding of the present invention. The schematic embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation to the present invention. Among them:

[0027] Figure 1 It is a schematic construction cross-section diagram of the water control method for downward mining in the near-aquifer working face according to an embodiment of the present invention;

[0028] Figure 2 It is a top view of the water-blocking curtain according to an embodiment of the present invention.

[0029] In the figure: 1. Water-blocking curtain; 11. Herringbone wall; 12. Transverse wall; 13. Longitudinal wall; 2. Pumping borehole; 3. Grouting bolt; 4. Working face affected by the aquifer. Detailed implementation manners

[0030] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art belong to the scope of protection of the present invention.

[0031] In the description of the present invention, the orientation or positional relationship indicated by terms such as "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention rather than requiring the present invention to be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention. The terms "connected" and "coupled" used in the present invention should be understood in a broad sense. For example, it can be a fixed connection or a detachable connection; it can be directly connected or indirectly connected through an intermediate component. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific circumstances.

[0032] The present invention will be described in detail below with reference to the drawings and in conjunction with embodiments. It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0033] According to a specific embodiment of the present invention, as Figure 1-2 shown, the present invention provides a water control method for downward mining of a working face near an aquifer. The water control method includes the following steps:

[0034] Step 1: Determine the number of working face designs and the working face succession order according to the distance relationship between the upper boundary of the coal seam and the aquifer and the water - resisting layer.

[0035] Step 2: Construct a water - retaining curtain 1 for the working face affected by the aquifer. The water - retaining curtain 1 is a pile - connected wall structure. In this embodiment, the pile - connected wall structure is formed by the interlocking of multiple piles. Among them, the piles can be selected from bored cast - in - place piles, cement mixing piles, rotary bored piles and other structures, and the appropriate pile type is selected according to the specific geological conditions. Using multiple piles to interlock to form a pile - connected wall has a small disturbance range during the construction process and also has a small impact on the underground aquifer and coal seam structure.

[0036] The water - retaining curtain 1 extends from the ground to the water - resisting layer, and the water - retaining curtain 1 covers the working face affected by the aquifer and the roadway near the working face in the vertical projection direction.

[0037] Step 3: Drill a pumping borehole 2 into the aquifer within the water - retaining curtain 1 and pump water, and at the same time grout into the aquifer until there is no water left within the range of the water - retaining curtain 1 and it is filled with grout.

[0038] Step 4: Start mining from the first working face at the deepest part of the coal seam. After the first working face is mined, detect the water inflow of the next working face and the roadway near the working face, and promptly carry out water drainage work until the last working face closest to the aquifer is mined.

[0039] Step 5: Before mining the last working face, detect the water inflow of the last working face and the nearby roadways, and carry out the work of water drainage and dewatering; if the detected water inflow is large, conduct supplementary grouting treatment within the range of the water retaining curtain 1 until the detected water inflow reaches the standard, and then carry out the mining operation of the last working face.

[0040] In this water control method, since the last working face is the closest to the aquifer, and both the caving zone and the water-conducting fissure zone of the last working face are very close to the aquifer, the aquifer has a greater impact on the last working face.

[0041] By constructing the water retaining curtain 1 from the ground to the aquitard, and the water retaining curtain 1 completely covers the working face affected by the aquifer in the vertical projection direction. First, the aquifer that has a greater impact on the working face is isolated by the water retaining curtain 1, so that the water inside the water retaining curtain 1 and the water outside the water retaining curtain 1 do not affect each other; then drill holes inside the water retaining curtain 1, lower the water extraction pipe into the drill holes for water extraction operations, and at the same time carry out grouting operations into the water retaining curtain 1. Due to the limitation of the water retaining curtain 1, most of the grouting liquid will stay within the water retaining curtain 1 and will not escape everywhere, and grouting can also raise the water level inside the water retaining curtain 1, thus making it more convenient for the water extraction operation to extract the water inside the water retaining curtain 1 completely, so that there is no water left inside the water retaining curtain 1; at the same time, after each working face is mined, water inflow inspection and treatment operations are carried out, which plays a role of double insurance and fundamentally ensures the safety of the working face mining.

[0042] Among them, the water retaining curtain 1 not only plays a role in water isolation, which can reduce the water extraction volume; but also plays a role in preventing the escape of the grouting liquid, which can further reduce the grouting volume; and grouting is carried out while pumping water, and the grouting liquid sinks to the bottom of the aquifer inside the water retaining curtain 1, thereby raising the water level inside the water retaining curtain 1, which makes it more convenient for the water extraction operation; moreover, water extraction operations are only carried out inside the water retaining curtain 1, and the aquifer outside the water retaining curtain 1 will not be over-pumped, protecting the groundwater resources, and thus also protecting the local ecological environment; in summary, the water retaining curtain 1, grouting operations and water extraction operations cooperate with each other. While achieving the effect of no water left inside the water retaining curtain 1, it can also greatly reduce the construction cost, improve the construction efficiency, and protect the ecological environment.

[0043] The water retaining curtain 1 is provided with a diversion wall facing the water flow direction of the aquifer, and the diversion wall has an inclination angle with the water flow direction of the aquifer. In an embodiment of the present application, a diversion wall with an inclination angle with the water flow direction is provided in front of the water retaining curtain 1, thus avoiding the direct impact of the aquifer water flow on the water retaining curtain 1 and ensuring the safety and effectiveness of the water retaining curtain 1.

[0044] The diversion wall is a chevron-shaped wall 11, and the tip of the chevron-shaped wall 11 faces the water flow direction of the aquifer. In an embodiment of the present application, through the diversion effect of the chevron-shaped wall 11, the water flow of the aquifer flows to both sides of the chevron-shaped wall 11, avoiding the water flow directly scouring the chevron-shaped wall 11 vertically, ensuring that the chevron-shaped wall 11 is subjected to as small a water flow impact as possible, thereby ensuring that the chevron-shaped wall 11 can always effectively play its diversion role and preventing the water flow from seeping into the inside of the water retaining curtain wall.

[0045] In the vertical projection direction, the chevron-shaped wall 11 is located on the front side of the front end of the working face 4 affected by the aquifer. In an embodiment of the present application, the chevron-shaped wall 11 is located on the front side of the front end of the working face 4 affected by the aquifer in the vertical projection direction, enabling the chevron-shaped wall 11 to cover a larger range in front of the aquifer affecting the working face.

[0046] The water retaining curtain 1 further includes two transverse walls 12, and the two transverse walls 12 are respectively connected to both sides of the chevron-shaped wall 11.

[0047] The distance between the two transverse walls 12 is greater than the width of the working face 4 affected by the aquifer, and in the vertical projection direction, both of the two transverse walls 12 are located outside the left and right sides of the working face 4 affected by the aquifer.

[0048] In an embodiment of the present application, the two transverse walls 12 are connected to both sides of the chevron-shaped wall 11. In the vertical projection direction, the two transverse walls 12 are arranged on the periphery of the working face, enabling the two transverse walls 12 to cover a larger range on the left and right sides of the aquifer affecting the working face, thereby facilitating subsequent treatment operations on the aquifer in the water retaining curtain 1.

[0049] The water retaining curtain 1 further includes a longitudinal wall 13, and the longitudinal wall 13 is connected to the ends of the two transverse walls 12 far from the chevron-shaped wall 11. In an embodiment of the present application, the chevron-shaped wall 11, the two transverse walls 12 and the longitudinal wall 13 enclose a completely closed curtain. The closed water retaining curtain 1 completely encloses the aquifer affecting the working face, and the lower part of the closed water retaining curtain 1 extends to the aquitard, so that the water bodies inside and outside the closed water retaining curtain 1 do not affect each other, thereby making it more convenient to pump and treat the inside of the closed water retaining curtain 1.

[0050] In the vertical projection direction, the longitudinal wall 13 is located on the rear side of the rear end of the working face 4 affected by the aquifer. In an embodiment of the present application, in the vertical projection direction, the longitudinal wall 13 is located outside the working face 4 affected by the aquifer, enabling the longitudinal wall 13 to cover a larger range on the rear side of the aquifer affecting the working face, thereby facilitating the water retaining curtain 1 to better enclose the aquifer affecting the working face.

[0051] In step 3, the pumping borehole 2 extends into the upper-middle part of the aquifer. A steel casing is arranged inside the pumping borehole 2, and a filter screen is arranged at the bottom of the steel casing. In an embodiment of the present application, a plurality of pumping boreholes 2 are provided, and the plurality of pumping boreholes 2 are evenly distributed within the water retaining curtain 1; the pumping borehole 2 extends into the upper-middle part of the aquifer, rather than directly into the lower part of the aquifer, because during the pumping process, grouting is carried out into the aquifer, and the grouting liquid will gradually raise the water level in the aquifer, so that the water level in the aquifer always remains in the upper-middle position, thus facilitating the pumping borehole 2 to pump out the water in the aquifer within the water retaining curtain 1, and further enabling to avoid the influence of the aquifer on the mining work of the last working face as much as possible.

[0052] And arranging the steel casing in the pumping borehole 2 can prevent the occurrence of borehole collapse of the pumping borehole 2, and the filter screen can filter sand and gravel well, thus avoiding the influence of sand and gravel on the pumping operation.

[0053] In step 3, grouting anchor rods 3 are arranged to grout the aquifer, and the bottom end of the grouting anchor rod 3 extends into the upper part of the water-resistant layer. In an embodiment of the present application, a plurality of grouting anchor rods 3 are provided, and the plurality of grouting anchor rods 3 are evenly distributed within the water retaining curtain 1, and the plurality of grouting anchor rods 3 and the plurality of pumping boreholes 2 are arranged in a staggered manner; the bottom end of the grouting anchor rod 3 extends into the water-resistant layer, so that the grouting anchor rod 3 can not only grout the aquifer, but also grout and reinforce the water-resistant layer.

[0054] In this embodiment, the water retaining curtain 1 extends to the bottom of the water-resistant layer. During grouting, due to the restrictive effect of the water retaining curtain 1, most of the grouting liquid will be retained within the water retaining curtain 1. The grouting liquid will first spread in the lowermost water-resistant layer to grout and reinforce the water-resistant layer. At this time, the water retaining curtain 1 and the bottom water-resistant layer completely wrap the part of the aquifer that affects the working face. With the continuous injection of the grouting liquid, the grouting liquid gradually accumulates at the bottom of the aquifer, thereby raising the water level of the water body in the aquifer, facilitating the pumping operation of the water retaining curtain 1; after the pumping and grouting operation is completed, there is basically no stored water in the aquifer within the water retaining curtain 1, and thus fundamentally solves the water inrush influence caused by the aquifer on the last working face, and as much as possible ensures the safety of the mining operation of the working face.

[0055] It can be understood that the above description is only exemplary, and the embodiments of the present application do not limit this.

[0056] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention are within the scope of the claims of the present invention awaiting approval.

Claims

1. A method for controlling water during downward mining near an aquifer working face, characterized in that: The water control method comprises the following steps: Step 1: Determine the number of working faces to be designed and the order of succession of working faces according to the distance relationship between the upper boundary of the coal seam and the aquifer and impermeable layer; Step 2, constructing a water retaining curtain on the working surface affected by the aquifer, wherein the water retaining curtain is a pile-connected wall structure; The water retaining curtain extends from the ground to the water-proof layer, and the water retaining curtain covers the working face affected by the aquifer and the tunnel near the working face in the vertical projection direction; Step 3, drilling a pumping hole in the water retaining curtain to the aquifer and pumping water, and injecting grout into the aquifer at the same time, until there is no water in the water retaining curtain and the aquifer is filled with grouting liquid; Step 4, mining is carried out upward from the first working face at the deepest part of the coal seam. After the mining of the first working face is completed, the water inflow is detected for the next working face and the roadway near the working face, and water is drained in time until the last working face closest to the aquifer is mined; Step 5, before mining the last working face, the water inflow of the last working face and the nearby tunnels is detected, and water drainage is performed; if the detected water inflow is large, additional grouting treatment is performed within the range of the water retaining curtain until the detected water inflow meets the standard before mining the last working face, and the water retaining curtain is provided with a guide wall facing the water flow direction of the aquifer, and the guide wall has an inclination angle with the water flow direction of the aquifer; In step 3, the pumping borehole extends into the middle and upper part of the aquifer, a steel casing is arranged inside the pumping borehole, and a filter is arranged at the bottom of the steel casing; A grouting anchor rod is arranged to grout the aquifer, and the bottom end of the grouting anchor rod extends into the upper part of the aquiclude.

2. The method for controlling water during downward mining near the aquifer working face according to claim 1, characterized in that: The diversion wall is a herringbone wall, and the tip of the herringbone wall faces the water flow direction of the aquifer.

3. The method for controlling water during downward mining near the aquifer working face according to claim 2, characterized in that: In the vertical projection direction, the herringbone wall is located at the front side of the front end of the working face affected by the aquifer.

4. The method for controlling water during downward mining near the aquifer working face according to claim 2, characterized in that: The water retaining curtain also includes two transverse walls, which are respectively connected to both sides of the herringbone wall.

5. The method for controlling water during downward mining near the aquifer working face according to claim 4 is characterized in that: The distance between the two transverse walls is greater than the width of the working surface affected by the aquifer, and in the vertical projection direction, the two transverse walls are located outside the left and right sides of the working surface affected by the aquifer.

6. The method for controlling water during downward mining near the aquifer working face according to claim 4, characterized in that: The water retaining curtain further comprises a longitudinal wall connected to ends of the two transverse walls away from the herringbone wall.

7. The method for controlling water during downward mining near the aquifer working face according to claim 6, characterized in that: In the vertical projection direction, the longitudinal wall is located at the rear side of the rear end of the working face affected by the aquifer.

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