Freezing outburst prevention control method for high pressure water in coal seam floor of short working face along gob

Abstract

The application discloses a kind of along empty roadway short working face coal seam floor high pressure water freezing outburst prevention control method, belong to coal underground mining floor water inrush prevention technical field, comprising the following steps: S1: determine the process parameters of freezing method, and the high pressure water of coal seam floor is detected;S2: first mining area is arranged;S3: excavate freezing chamber and install freezing equipment;S4: construction extends to aquifer freezing borehole;S5: install freezing pipeline and carry out freezing operation;S6: floor high pressure water is pumped out;S7: hydrologic observation borehole is constructed in along empty roadway floor;S8: first working face is mined and excavates second working face recovery roadway;S9: excavate second working face freezing chamber and construction freezing borehole;S10: freezing equipment completes relocation operation before first working face stop mining;S11: repeat S5 to S10 step realizes mining area working face safe mining.The application has the advantages that: it is favorable to improve the production efficiency of mine, and the safety of production is guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of water inrush prevention and control in underground coal mining floors, and in particular to a method for preventing and controlling high-pressure water freezing in coal seam floors of short working faces along gob-side entryways. Background Art

[0002] As mining gradually shifts to deeper areas, the water pressure in the coal seam floor aquifer gradually increases, and coal mine floor water inrush accidents occur frequently, making the floor water inrush problem one of the major hazards affecting mine safety production.

[0003] Currently, mine water inrush prevention and control in my country primarily focuses on methods such as "advance detection, water drainage and pressure reduction, and grouting reinforcement." For example, Chinese Patent CN201910733012.8 discloses a method for preventing limestone water in coal mining floors, Chinese Patent CN201610330340.X discloses a method for preventing water inrush channels caused by faults in coal mining floors, and Chinese Patent CN201510297909.2 discloses a method for transforming floor limestone aquifers into natural and artificial composite complete aquicludes. All of these methods, based on comprehensive exploration of the hydrogeological conditions of the coal mine floor, implement grouting reinforcement and transformation at the target strata to enhance the integrity and overall strength of the floor aquicludes. Technical drawbacks of these methods include the inability of grouting reinforcement to completely block the outburst of pressurized water in the floor, the lack of effective evaluation methods for grouting effectiveness, and the potential for new water channels to form under the influence of dynamic pressure during working face mining, potentially opening previously blocked water channels again.

[0004] Chinese patent CN202110303828.4 discloses a method for preventing coal seam floor water bursts by freezing high-pressure water. This method uses freezing construction to extract high-pressure water from the floor within the freezing curtain based on the detection of the floor aquifer. However, the defect of this method is that it is only applicable to independent mining areas and does not consider the impact of mining in other mining areas on the prevention and control of floor water bursts. Since the goaf-side tunnel is shared by two mining areas with the same return tunnel, the prevention and control of floor water bursts should consider the timing of relocating the equipment from the first mining area to the second mining area and the timing of stopping the freezing of the frozen boreholes in the first mining area.

[0005] Chinese patent CN201410459354.2 discloses a method for analyzing the risk of water inrush from the floor of a deep well. This method performs a weighted analysis of multiple factors, including aquifer water pressure and water richness, working face mining height, mining depth, mining length, ground stress, and mining disturbance, to establish a theoretical model for predicting and analyzing the risk of water inrush. However, this method does not propose specific measures for preventing and controlling water inrush, and its prediction model lacks sufficient engineering practice as support. Mine conditions vary greatly, making it difficult to be universally applicable. Furthermore, some mining areas use methods such as lowering the mining height, stratified mining, and lane mining to prevent and control water inrush. These methods not only have unsatisfactory prevention and control effects, but also reduce coal resource recovery rates. Therefore, balancing the efficient mining of coal resources with the effective prevention and control of floor water inrush is a scientific challenge that the coal industry urgently needs to address. Summary of the Invention

[0006] The present invention aims to solve one of the technical problems in the related art at least to a certain extent.

[0007] In order to achieve the above-mentioned purpose, the present invention proposes a method for preventing water bursts from freezing in the coal seam floor of a short working face with a goaf and a tunnel. The method for preventing water bursts from freezing in the coal seam floor of a short working face with a goaf and a tunnel can take into account both the efficient mining of coal resources and the effective prevention and control of water bursts from the floor, which is beneficial to improving the production efficiency of the mine and ensuring the safety of production.

[0008] The technical solution provided by the present invention is: a method for preventing sudden outbursts from freezing high-pressure water in the coal seam floor of a short working face with a gob-side entry, comprising the following steps:

[0009] S1: Determine the process parameters of the freezing method through experiments, and obtain the distribution range and layer position of the high-pressure water in the bottom plate through detection;

[0010] S2: Excavating a mining roadway to one side of the main roadway in the mining area, excavating a freezing chamber in the mining roadway, and installing freezing equipment in the freezing chamber. The mining roadway and the main roadway in the mining area intersect to form a first mining area. The mining roadway includes a working face cut-eye roadway and a gob-side retained roadway;

[0011] S3: During the excavation of the mining roadway, multiple freezing boreholes extending to the aquifer are simultaneously constructed in the mining area main roadway and the mining roadway, and the multiple freezing boreholes are arranged at set intervals along the mining area main roadway or the mining roadway;

[0012] S4: Install a freezing pipe extending to the aquifer in the freezing borehole, and use freezing equipment to freeze the aquifer below the floor of the main roadway in the mining area and the aquifer below the floor of the mining roadway;

[0013] S5: After a freezing curtain is formed below the first mining area, a pumping system is arranged in the mining tunnel and the high-pressure water in the floor of the area surrounded by the freezing curtain is pumped out by the pumping system;

[0014] S6: Before mining in the first mining area, the freezing operation of the cut-eye roadway is stopped, and multiple hydrological observation boreholes are constructed in the floor at the intersection of the cut-eye roadway and the gob-side roadway. The multiple hydrological observation boreholes are inclined toward the first mining area and penetrate the aquifer. The hydrological observation boreholes are used to monitor the time required for water inrush to occur again after freezing in the cut-eye roadway stops.

[0015] S7: Carry out the mining operation and gob-side lane retaining construction operation in the first mining area, and stop freezing the frozen drill holes in the main lane of the mining area and the mining lane when they are spaced at a set distance from the first mining area, and continue until the mining of the first mining area is completed.

[0016] In some embodiments, step S7 further includes: while mining in the first mining area, excavating a mining roadway of the second mining area on the other side of the main roadway of the mining area, and the mining roadway of the first mining area is reserved and used as a gob-side roadway of the second mining area.

[0017] In some embodiments, the method for preventing sudden outbursts from freezing of high-pressure water in the coal seam floor of a short working face with a goaf-side entry also includes step S8: before the mining of the first mining area is completed, a freezing chamber is excavated and freezing drilling is constructed in the mining tunnel of the second mining area.

[0018] In some embodiments, the method for preventing sudden outbursts from freezing high-pressure water in the coal seam floor of a short working face with gob-side entry retention further includes step S9: determining a time to relocate the freezing equipment during mining in the first mining area, and relocating the freezing equipment to a freezing chamber in the second mining area when mining is stopped in the first mining area, wherein the relocation time T of the freezing equipment satisfies the following formula:

[0019]

[0020] Where: T a T is the mining time of the unmined area in this mining area; b is the mining time increased in the unmined area of ​​this mining area due to geological factors such as faults and structures; L is the mining length of the unmined area of ​​this mining area; V is the daily advance of the working face; L1 is the strike length of this mining area; L2 is the length of the unmined protective coal pillar; T c The mining time of the mined area in this mining area; T1, T2, T3...T N The time of water inrush from the borehole for hydrological observation.

[0021] In some embodiments, the method for preventing sudden outbursts from being caused by freezing of high-pressure water in the coal seam floor of a short working face along the goaf also includes step S10: after the freezing equipment relocation work is completed, a freezing curtain for the aquifer in the floor of the second mining area is constructed, and the high-pressure water in the floor of the freezing curtain is pumped out, and then the second mining area is mined, and the above steps S6 to S9 are repeated until the mining of all working faces in the mining area is completed.

[0022] In some embodiments, the strike length of the first mining block is not more than 800 meters, and the length of the open-off cut roadway is not more than 200 meters.

[0023] In some embodiments, the freezing chamber is arranged in the mining roadway between the main roadway of the mining block and the stop line of the mining block.

[0024] In some embodiments, the freezing borehole penetrates the aquifer of the coal seam floor, the length dimension of the freezing borehole beyond the aquifer is not less than one quarter of the thickness of the aquifer, the spacing between two adjacent freezing boreholes is not more than 1.5 meters, the freezing borehole extends along the vertical direction, and the spacing between the freezing borehole and the non-mining side coal wall is not less than 200 millimeters.

[0025] In some embodiments, the freezing process parameters are the active freezing temperature, the maintenance freezing temperature, and the freezing curtain width, the active freezing temperature is -28°C to -30°C, the maintenance freezing temperature is -22°C to -25°C, and the width of the freezing curtain is not less than 1.5 meters.

[0026] In some embodiments, the hydrological observation borehole needs to be completely constructed on the day when the open-off cut roadway stops the freezing operation, and the hydrological observation borehole should be constructed approximately parallel to and close to the plane where the freezing borehole is located in the open-off cut roadway. The time from the completion of the construction of the hydrological observation borehole to the next water inrush in the hole is used as the reference for the timing of the removal of the freezing equipment in the freezing chamber.

[0027] In some embodiments, the freezing boreholes in the main roadway of the mining block and in the mining roadway stop freezing at a set interval from the mining block. The set interval at which the freezing boreholes in the main roadway of the mining block and in the mining roadway stop freezing is as follows: when the first mining block is mined, first, stop the freezing operation of all the freezing boreholes in the open-off cut roadway and stop the freezing operation of the freezing boreholes in the first mining block mining roadway between the open-off cut roadway and 20 meters therefrom, then use the fully mechanized mining equipment to mine and advance from the open-off cut roadway to the side of the main roadway of the mining block. In this process, the freezing operation of the freezing boreholes in the first mining block mining roadway between the coal mining face and 20 meters therefrom is gradually stopped, while the freezing operation in the first mining block gob-side entry does not need to be gradually stopped as the first mining block advances, and the freezing operation of the main roadway of the mining block stops when the freezing equipment is removed during the mining of the first mining block.

[0028] The advantages of the present invention compared with the prior art are: (1) after the freezing method is adopted, only the pressurized water in the freezing curtain needs to be pumped out to reduce it to a safe level, which greatly reduces the workload of pumping in the mining area; (2) the present method can be carried out simultaneously with other working processes on the working face without affecting the normal production of the mine; (3) the present method has good water-proof performance and strong adaptability to various complex geological conditions. It can improve the strength of the rock layer of the bottom plate of the mining roadway, reduce the deformation of the surrounding rock of the roadway bottom plate, and realize safe and efficient production of the mine.

[0029] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic cross-sectional diagram of the freezing arrangement within the mining range of the first mining area of ​​the present invention;

[0031] Figure 2 It is a schematic plan view of the freezing arrangement within the mining range of the first mining area of ​​the present invention;

[0032] Figure 3 This is a schematic cross-sectional diagram of the freezing arrangement within the mining range of the second mining area of ​​the present invention;

[0033] Figure 4 It is a schematic plan view of the freezing arrangement within the mining range of the second mining area of ​​the present invention;

[0034] In the attached figure: 1. First mining area; 2. Second mining area; 3. Mining tunnel in the first mining area; 4. Gob-side tunnel in the first mining area; 5. Mining tunnel in the second mining area; 6. Frozen borehole; 7. Frozen curtain; 8. Aquifer; 9. Main tunnel in the mining area; 10. High-pressure water; 11. Frozen chamber; 12. Stop mining line; 13. Frozen pipeline; 14. Filling wall; 15. Hydrological observation borehole. DETAILED DESCRIPTION

[0035] The present invention is described in further detail below.

[0036] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The following embodiments are used to illustrate the present invention but are not used to limit the scope of the present invention.

[0037] like Figures 1 to 4 As shown, the method for preventing sudden outbursts by freezing high-pressure water 10 in the coal seam floor of the short working face of the gob-side entry 4 in the first mining area of ​​this embodiment includes the following steps:

[0038] S1: Determine the process parameters of the freezing method through experiments, and detect the high-pressure water 10 on the coal seam floor to obtain the distribution range and layer position of the high-pressure water 10.

[0039] Specifically, the process parameters related to the freezing method can be obtained through ground tests, the freezing parameters including the maximum conveying distance of the freezing equipment, the active freezing temperature, the maintenance freezing temperature, and the freezing time required for different freezing curtains 7 widths, through which test basis can be provided for the bottom plate high-pressure water 10 freezing parameter setting.

[0040] In addition, the high-pressure water 10 in the coal seam floor needs to be hydrologically detected by a detection device, and the detection methods can be geophysical prospecting, roadway prospecting, and drilling, etc. Through hydrological detection, the hydrogeological conditions of the high-pressure water 10 in the coal seam floor can be obtained and mastered, so that the distribution range and horizon of the high-pressure water 10 can be determined, and hydrological data for the freezing method outburst prevention mining can be provided.

[0041] S2: excavate a recovery roadway on one side of the mining district main roadway 9, excavate a freezing chamber 11 in the recovery roadway, and install a freezing device in the freezing chamber 11, the recovery roadway and the mining district main roadway 9 intersect to form a first mining district 1, and the recovery roadway includes a working face cut hole roadway and a first mining district gob-side entry 4;

[0042] Specifically, as shown in Figure 1 and Figure 2 , a plurality of mining districts are arranged on one side of the mining district main roadway 9, and each mining district uses the first mining district gob-side entry 4 for recovery operation, that is, the recovery roadway reserved by the previous mining district can be used as the air return roadway or the transportation roadway of the next mining district. Therefore, before the recovery of the current mining district (for convenience, the current mining district will also be referred to as the first mining district 1 below), only the recovery roadway needs to be excavated on one side of the mining district main roadway 9, and the recovery roadway and the mining district main roadway 9 form the first mining district 1 to be mined.

[0043] For example, as shown in Figure 1 , the first mining district recovery roadway 3 and the first mining district gob-side entry 4 are the recovery roadway of the first mining district 1, and the first mining district gob-side entry 4 is reserved when the first mining district 1 is recovered. When the second mining district 2 is mined, the first mining district gob-side entry 4 can be used as the air return roadway or the transportation roadway of the second mining district 2.

[0044] Preferably, during the recovery of the first mining district 1, the first mining district gob-side entry 4 can be reserved by setting a filling wall 14 in the first mining district gob-side entry 4.

[0045] Specifically, as shown in Figure 1 , when the recovery roadway of the first mining district 1 is excavated, the freezing chamber 11 is excavated in the first mining district recovery roadway 3 and the first mining district gob-side entry 4, and the freezing chamber 11 can be arranged near the first mining district 1 or near the next mining district. After the freezing chamber 11 is arranged, the freezing device is installed in the freezing chamber 11.

[0046] In this embodiment, the freezing chamber 11 is a cubic chamber with a length of 15 m, a height of 2 m and a width of 4 m.

[0047] S3: During the excavation of the mining tunnel, multiple freezing boreholes 6 extending to the aquifer 8 are simultaneously constructed in the mining area tunnel 9 and the mining tunnel. The multiple freezing boreholes 6 are arranged at set intervals along the mining area tunnel 9 or the mining tunnel.

[0048] Specifically, if Figure 1 and Figure 2 As shown, during the excavation of the return mining tunnel in the first mining area 1, multiple frozen drill holes 6 can be constructed in the area corresponding to the mining area main tunnel 9 and the first mining area 1, in the goaf-side tunnel 4 in the first mining area, and on the bottom plate of the excavated return mining tunnel 3 in the first mining area.

[0049] It should be noted that the overall arrangement length of the multiple frozen drill holes 6 in the main tunnel 9 of the mining area corresponds to the width of the first mining area 1, and the overall arrangement length of the multiple frozen drill holes 6 in the goaf-side tunnel 4 of the first mining area and the return mining tunnel 3 of the first mining area corresponds to the overall strike length of the first mining area 1.

[0050] Preferably, the multiple frozen drill holes 6 in the main tunnel 9 of the mining area are arranged at intervals along the extension direction of the main tunnel 9 of the mining area, the multiple frozen drill holes 6 in the recovery tunnel 3 of the first mining area are arranged at intervals along the extension direction of the recovery tunnel 3, and the multiple frozen drill holes 6 in the empty tunnel 4 of the first mining area are arranged at intervals along the extension direction of the empty tunnel 4 of the first mining area.

[0051] Preferably, the spacing between any two adjacent freezing boreholes 6 is 1 meter to 1.5 meters. For example, the spacing between any two adjacent freezing boreholes 6 can be 1 meter, 1.2 meters, 1.5 meters, etc. Thus, freezing through can be achieved between any two adjacent freezing boreholes 6 while consuming less energy for freezing equipment, thereby facilitating the subsequent formation of the freezing curtain 7.

[0052] S4: A freezing pipeline 13 extending to the aquifer is installed in the freezing borehole 6, and freezing equipment is used to perform freezing operations on the aquifer 10 below the bottom plate of the main tunnel 9 in the mining area and the aquifer 10 below the bottom plate of the mining tunnel.

[0053] Specifically, as all the mining tunnels in the first mining area 1 are connected, freezing pipes 13 can be installed in the freezing boreholes 6 that have been constructed in the mining area main tunnel 9 and the mining tunnel in the first mining area 1. All freezing pipes 13 are connected to the freezing equipment. Thus, cold air can be introduced into the freezing pipes 13 through the freezing equipment, thereby achieving the freezing of the aquifer 8 around the freezing borehole 6.

[0054] S5: After the freezing curtain 7 is formed under the first mining area 1, the drainage system is arranged in the recovery roadway, and the high-pressure water 10 in the area surrounded by the freezing curtain 7 is drained by using the drainage system.

[0055] Specifically, with the freezing operation, the aquifer 8 between any two adjacent freezing boreholes 6 is frozen through, so that the freezing curtain 7 is formed between any two adjacent freezing boreholes 6, the freezing curtains 7 are connected in series to form a body and form an ice wall-like structure, thereby playing a role of blocking the high-pressure water 10.

[0056] It should be noted that the freezing device includes two freezing modes, namely, an active freezing temperature mode and a maintenance freezing temperature mode. Before the freezing curtain 7 is formed, the freezing device can adopt the active freezing temperature mode. At this time, the active freezing temperature of the freezing device can be -28°C to -30°C. It should be noted that the active freezing temperature is lower than the maintenance freezing temperature, so that the formation of the freezing curtain 7 can be accelerated.

[0057] The freezing device is continuously set in the active freezing temperature mode for a certain period of time, for example, 1 day to 3 days. Then the freezing device can be switched from the active freezing temperature mode to the maintenance freezing temperature mode, and the maintenance freezing temperature is -22°C to -25°C. Thus, the frozen state of the freezing curtain 7 can be maintained, so that the high-pressure water 10 under the first mining area 1 is closed.

[0058] After the freezing curtain 7 is formed, the high-pressure water 10 in the area surrounded by the freezing curtain 7 (the area under the first mining area 1) can be drained by using the drainage system. In this way, on the one hand, the drainage of the high-pressure water 10 under the first mining area 1 can be realized in advance, and on the other hand, the floor water inrush in the recovery roadway of the first mining area 1 is avoided, the safety of the recovery roadway of the first mining area 1 is improved, and the smooth production is ensured.

[0059] It should be noted that the main distribution area of the water in the aquifer 8 can be determined by using the detected hydrogeological data, and then the drainage borehole can be arranged from the recovery roadway of the first mining area 1 to the area, the drainage pipeline is arranged in the drainage borehole, and then the drainage pipeline is connected with the drainage system, so that the drainage of the high-pressure water 10 can be realized.

[0060] S6: Before the first mining area 1 is recovered, the freezing operation of the open-off cut roadway is stopped, a plurality of hydrological observation boreholes are constructed on the floor at the intersection position of the open-off cut roadway and the gob-side entry, the plurality of hydrological observation boreholes are inclined to the first mining area 1 side, and the hydrological observation boreholes penetrate the aquifer. The hydrological observation borehole is used to monitor the time required for water inrush again after the freezing of the open-off cut roadway is stopped.

[0061] Specifically, as shown in FIG. 6, the hydrological observation boreholes 9 are arranged on the floor at the intersection position of the open-off cut roadway and the gob-side entry. Figure 3As shown, before the formal mining of the first mining area 1, a plurality of hydrological observation drill holes 15 need to be drilled in the first mining area along the gob 4. The hydrological observation drill holes 15 are inclined to the side of the first mining area 1, and the hydrological observation drill holes 15 penetrate the aquifer 8 from top to bottom. Through the hydrological observation drill holes 15, the high-pressure water 10 under the floor can be monitored, so that the time from stopping freezing to the next water inrush can be known.

[0062] It should be noted that the hydrological observation drill holes 15 can be arranged in multiple, such as Figure 4 As shown, the inclination angle of the plurality of hydrological observation drill holes 15 can be appropriately changed, so that the monitoring of the high-pressure water 10 in the aquifer 8 at different heights can be realized.

[0063] In addition, since the hydrological observation drill holes 15 are arranged in the first mining area along the gob 4, during the mining of the first mining area 1, the first mining area along the gob 4 needs to be reserved and used as the second mining area 2 mining roadway. Therefore, the monitoring of the hydrological observation drill holes 15 can not be affected by the mining of the first mining area 1, and the effective monitoring of the hydrological observation drill holes 15 can continue until the end of the mining of the first mining area 1.

[0064] S7: Perform the mining operation of the first mining area 1 and the construction operation of the first mining area along the gob 4. The freezing drill holes in the mining area main roadway 9 and the mining roadway stop freezing when the distance between the first mining area 1 is set to a certain interval, and until the mining of the first mining area 1 is completed.

[0065] Specifically, as shown Figure 2 As shown, during the mining of the first mining area 1, the freezing pipeline 13 in the cut roadway needs to be first shut down, and the freezing pipeline 13 between the cut roadway 20 meters and the first mining area mining roadway 3 needs to be shut down. Then, the fully mechanized mining equipment can be used to mine and advance from the cut roadway to the side of the mining area main roadway 9.

[0066] It should be noted that the freezing pipeline 13 in the first mining area along the gob 4 does not need to be gradually shut down with the advancement of the first mining area 1.

[0067] In some embodiments, in step S7, the second mining area 2 mining roadway is excavated on the other side of the mining area main roadway 9 while the first mining area 1 is mined. The mining roadway of the first mining area 1 is reserved as the along-gob roadway of the second mining area 2.

[0068] Specifically, as shown Figure 4 As shown, during the mining of the first mining area 1, the mining roadway (second mining area mining roadway 5) of the next mining area (second mining area 2) can be arranged in advance. After the mining of the first mining area 1, the first mining area along the gob 4 can become the reserved roadway of the second mining area 2. Therefore, the mining efficiency can be improved, and the interface time of the working face can be shortened.

[0069] In some embodiments, the method for controlling freezing of high-pressure water 10 in the coal seam floor of a short working face along the goaf 4 in the first mining area also includes step S9: before the mining of the first mining area 1 is completed, a freezing chamber 11 is excavated and a freezing borehole 6 is constructed in the mining tunnel 5 of the second mining area 2.

[0070] Specifically, if Figure 4 As shown, before the mining of the first mining area 1 is completed, the mining tunnel of the second mining area 2 is excavated, and the freezing chamber 11 is excavated in the mining tunnel 5, and the freezing drill holes 6 are gradually constructed as the mining tunnel is excavated. After the mining of the first mining area 1 is completed, the mining tunnel of the second mining area 2 is completely penetrated and all construction operations of the freezing drill holes are completed.

[0071] In some embodiments, the method for preventing sudden outbursts by freezing high-pressure water 10 in the coal seam floor of a short working face of a gob-side entry 4 in the first mining area further includes step S9: determining a time to relocate a freezing device during mining in the first mining area 1 and relocating the freezing device to a freezing chamber 11 in the second mining area 2 when mining is stopped in the first mining area 1, wherein a relocation time T of the freezing device satisfies the following formula:

[0072]

[0073] Where: T a T is the mining time of the unmined area in this mining area (d); b is the mining time (d) increased by the unmined area of ​​this mining area due to geological factors such as faults and structures; L is the mining length of the unmined area of ​​this mining area; V is the daily advance of the working face (m / d); L1 is the strike length of this mining area (m); L2 is the length of the unmined protective coal pillar ( Figure 4 Protective coal pillar between the stop mining line 12 and the main roadway 9 in the mining area), unit (m); T c is the mining time of the mined area in this mining area (d); T1, T2, T3···T N The water inrush time of hydrological observation borehole 15 (d).

[0074] Specifically, if Figure 4 As shown, before the mining of the first mining area 1 is almost finished, a freezing chamber 11 can be excavated in the mining roadway 5 of the second mining area 2. Then, the freezing operation of the freezing chamber 11 in the mining roadway 3 of the first mining area 1 can be completely stopped, and the freezing equipment of the freezing chamber 11 in the mining roadway 3 of the first mining area 1 can be moved to the freezing chamber 11 in the mining roadway 5 of the second mining area 2. In this way, the boundary time of the working face can be further shortened and the production efficiency of the mine can be improved.

[0075] Specifically, it takes a certain amount of time for the freezing equipment to be transported between working faces. In order to avoid the problem of long handover time between working faces, the moving time of the freezing equipment needs to satisfy the above formula, that is, the moving time T of the freezing equipment does not exceed the water inrush time monitored by the minimum hydrological observation borehole 15. In this way, the safe recovery of the first mining area 1 can be guaranteed, and the safe evacuation of the freezing equipment can also be guaranteed.

[0076] In addition, the timing of moving the freezing equipment should also match the length of the unmined coal wall in the first mining area 1. In other words, the length of the unmined coal wall in the first mining area 1 can be measured to determine whether to start moving the freezing equipment. In other words, the freezing equipment must be removed before the mining area advances to the stop line 12.

[0077] In some embodiments, the method for controlling freezing of high-pressure water 10 in the coal seam floor of a short working face along the goaf 3 to prevent sudden outbursts also includes step S10: after the relocation of the freezing equipment is completed, a freezing curtain for the aquifer in the floor of the second mining area is constructed, and the high-pressure water in the floor of the freezing curtain is pumped out, and then the second mining area is mined, and the above steps S6 to S9 are repeated until the mining of all working faces in the mining area is completed.

[0078] Specifically, if Figure 4 As shown, after the first mining area 1 is mined, the above steps are repeated to mine the second mining area 2, and then the above steps are repeated again until all coal seams on one side of the main tunnel 9 of the mining area are mined.

[0079] In some embodiments, the length of the mining roadway does not exceed 800 meters, and the length of the cut-eye roadway does not exceed 200 meters. Specifically, the mining roadway can be the first mining roadway 4 or the second mining roadway 5, and the mining roadway can be 500 meters, 600 meters, 700 meters, 800 meters, etc. The length of the cut-eye roadway is the length of the mined coal wall at the working face, and the length of the cut-eye roadway can be 100 meters, 150 meters, 200 meters, etc. This ensures the freezing effect of the freezing curtain 7, preventing the working face from being too large and difficult to freeze.

[0080] In some embodiments, the freezing chamber 11 is arranged in the mining tunnel portion between the main tunnel 9 of the mining area and the stop mining line 12 of the mining area.

[0081] Specifically, if Figure 4 As shown, the freezing chamber 11 is located in the tunnel between the main tunnel 9 and the stop mining line 12 in the mining area. Since this is to protect the coal pillar, the freezing chamber 11 is less disturbed and will not affect the evacuation of the freezing equipment.

[0082] In some embodiments, the freezing borehole 6 passes through the aquifer 8 of the coal seam floor, and the length of the freezing borehole 6 exceeding the aquifer 8 is not less than one-quarter of the thickness of the aquifer 8. The distance between two adjacent freezing boreholes 6 does not exceed 1.5 meters. The freezing borehole 6 extends in the vertical direction, and the distance between the freezing borehole 6 and the non-mining side coal wall is not less than 200 mm.

[0083] Specifically, if Figure 1 and Figure 2 As shown, the freezing borehole 6 can be arranged vertically along the vertical direction and can penetrate the aquifer 8. The length of the freezing borehole 6 through the aquifer 8 should be no less than one-quarter of the thickness of the aquifer 8. For example, when the thickness of the aquifer 8 is 40 meters, the length of the freezing borehole 6 below the aquifer 8 should be no less than 10 meters. In this way, the aquifer 8 can be fully frozen and the freezing effect can be guaranteed.

[0084] The freezing borehole 6 is set in the roadway away from the coal wall of the first mining area 1, and the distance between the freezing borehole 6 and the non-mining side coal wall can be 200 mm, 250 mm, etc. In this way, the impact of mining on the freezing borehole 6 can be avoided, which is conducive to extending the freezing time.

[0085] In some embodiments, the width of the freezing curtain 7 is not less than 1.5 meters. For example, the width of the freezing curtain 7 can be 1.5 meters, 2 meters, 2.5 meters, etc., thereby ensuring the freezing effect and ensuring safe mining of the working face.

[0086] In some embodiments, the frozen drill holes in the mining tunnel of the previous working face can be used as frozen drill holes in the gob-side retaining tunnel of the next working face, thereby reducing the construction volume of frozen drill holes and further reducing mining costs.

[0087] In some embodiments, the hydrological observation borehole 15 needs to be completed on the day when the freezing operation of the cut-eye tunnel is stopped, and the hydrological observation borehole 15 should be approximately parallel to the plane where the freezing borehole 6 in the cut-eye tunnel is located and constructed close to the plane. The time from the completion of the hydrological observation borehole 15 to the next water inrush in the hole is used as the time when the bottom plate aquifer 8 is connected again after the cut-eye tunnel stops freezing. The minimum value of the water inrush time of all hydrological observation boreholes 15 is one of the references for the timing of relocation of the freezing equipment in the freezing chamber 11.

[0088] In some embodiments, the frozen drill holes 6 in the mining area main tunnel 9 and the return mining tunnel stop freezing when they are at a set interval from the mining area of ​​the first mining area 1. The interval setting interval for stopping the freezing of the frozen drill holes 6 in the mining area main tunnel 9 and the return mining tunnel is as follows: when mining in the first mining area 1, first shut down the freezing operation of all frozen drill holes 6 in the cut-eye tunnel and shut down the freezing operation of the frozen drill holes 6 in the return mining tunnel of the first mining area 1 within 20 meters from the cut-eye tunnel. Then, use the comprehensive mining equipment to advance mining from the cut-eye tunnel to the side of the mining area main tunnel 9. In this process, gradually shut down the freezing operation of the frozen drill holes 6 in the return mining tunnel of the first mining area 1 within 20 meters from the coal mining working face. The freezing operation in the goaf-retained tunnel 4 of the first mining area 1 does not need to be gradually shut down as the first mining area 1 advances. The freezing operation of the mining area main tunnel 9 will be stopped when the freezing equipment is relocated during the mining of the first mining area 1.

[0089] In the description of this specification, the reference terms "one embodiment," "some embodiments," "example," "specific example," or "some examples" mean that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0090] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to the embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the claims and their equivalents.

Claims

1. A method for preventing sudden outbursts from freezing high-pressure water in the coal seam floor of a short working face with a gob-side entry, characterized in that The following steps are involved: S1. Determine the process parameters of the freezing method through experiments, and obtain the distribution range and layer position of the high-pressure water in the bottom plate through detection; S2. Excavating a mining roadway to one side of the main roadway in the mining area, excavating a freezing chamber in the mining roadway, and installing a freezing device in the freezing chamber. The mining roadway and the main roadway in the mining area intersect to form a first mining area. The mining roadway includes a working face cut-eye roadway and a gob-side roadway. S3. During the excavation of the mining roadway, a plurality of freezing boreholes extending to the aquifer are simultaneously constructed in the mining area main roadway and the mining roadway, wherein the plurality of freezing boreholes are arranged at predetermined intervals along the mining area main roadway or the mining roadway; S4. Install a freezing pipe extending to the aquifer in the freezing borehole, and use freezing equipment to freeze the aquifer below the floor of the main roadway in the mining area and the aquifer below the floor of the mining roadway; S5. After a freezing curtain is formed below the first mining area, a pumping system is arranged in the mining tunnel and the high-pressure water in the floor of the area surrounded by the freezing curtain is pumped out by the pumping system; S6. Before mining in the first mining area, freeze maintenance operations in the cut-eye roadway are stopped, and multiple hydrological observation boreholes are constructed in the floor at the intersection of the cut-eye roadway and the gob-side entry. The multiple hydrological observation boreholes are inclined toward the first mining area and penetrate the aquifer. The hydrological observation boreholes are used to monitor the time required for water inrush to recur after freezing in the cut-eye roadway stops. S7, performing the mining operation and gob-side entry retaining operation in the first mining area, stopping freezing of the frozen drill holes in the main lane of the mining area and the mining roadway when they are spaced from the mining area of ​​the first mining area by a set distance, and continuing until the mining of the first mining area is completed; S8. Before the mining in the first mining area is completed, a freezing chamber is excavated in the mining roadway of the second mining area and freezing holes are constructed; S9. Determine the timing for relocating the freezing equipment during the mining period of the first mining area and relocate the freezing equipment to the freezing chamber of the second mining area before stopping mining in the first mining area. The relocation time T of the freezing equipment satisfies the following formula: ； Where: T a T is the mining time of the unmined area in this mining area; b is the mining time increased in the unmined area of ​​this mining area due to geological factors such as faults and structures; L is the mining length of the unmined area of ​​this mining area; V is the daily advance of the working face; L1 is the strike length of this mining area; L2 is the length of the unmined protective coal pillar; T c The mining time of the mined area in this mining area; T1, T2, T3...T N The time of water inrush from the borehole for hydrological observation.

2. The method for preventing sudden outbursts from freezing high-pressure water in the coal seam floor of a short working face with gob-side entry retention according to claim 1 is characterized in that Step S7 also includes: while mining in the first mining area, excavating the mining roadway of the second mining area on the other side of the main roadway of the mining area, and reserving part of the mining roadway of the first mining area as the gob-side roadway of the second mining area.

3. The method for preventing sudden outbursts from freezing high-pressure water in the coal seam floor of a short working face with gob-side entry retention according to claim 1 is characterized by: The method also includes step S10, after the freezing equipment relocation work is completed, constructing a freezing curtain of the aquifer on the bottom plate of the second mining area, and draining the high-pressure water on the bottom plate inside the freezing curtain, and then mining the second mining area, repeating the above steps S6 to S9 until the mining of all mining areas is completed.

4. The method for preventing sudden outbursts from freezing high-pressure water in the coal seam floor of a short working face with gob-side entry retention according to claim 1 is characterized in that: The strike length of the first mining area does not exceed 800 meters, and the length of the cut-eye tunnel does not exceed 200 meters.

5. The method for preventing sudden outbursts from freezing high-pressure water in the coal seam floor of a short working face with gob-side entry retention according to claim 1 is characterized in that: The freezing chamber is arranged in the mining tunnel between the main tunnel of the mining area and the stop mining line of the current working mining area.

6. The method for preventing sudden outbursts from freezing high-pressure water in the coal seam floor of a short working face with gob-side entry retention according to claim 1 is characterized in that: The freezing borehole passes through the aquifer of the coal seam floor, and the length of the freezing borehole beyond the aquifer is not less than one-quarter of the thickness of the aquifer. The distance between two adjacent freezing boreholes does not exceed 1.5 meters. The freezing borehole extends in the vertical direction, and the distance between the freezing borehole and the non-mining side coal wall is not less than 200 mm.

7. The method for preventing sudden outbursts from freezing high-pressure water in the coal seam floor of a short working face with gob-side entry retention according to claim 1 is characterized in that: The freezing process parameters are active freezing temperature, maintenance freezing temperature and freezing curtain width. The active freezing temperature is -28°C to -30°C, the maintenance freezing temperature is -22°C to -25°C, and the width of the freezing curtain is not less than 1.5 meters.

8. The method for preventing sudden outbursts from freezing high-pressure water in the coal seam floor of a short working face with gob-side entry retention according to claim 1 is characterized in that: The hydrological observation boreholes need to be completed on the day when the freezing operation in the cut-eye tunnel is stopped, and the hydrological observation boreholes should be approximately parallel to the plane where the freezing boreholes in the cut-eye tunnel are located and constructed close to the plane. The time from the completion of the hydrological observation borehole construction to the time when water bursts again in the hole will be used as the time when the bottom plate aquifer is connected again after the cut-eye tunnel stops freezing. The minimum value of the water burst time of all hydrological observation boreholes is one of the references for the timing of relocating the freezing equipment in the freezing chamber.

9. The method for preventing sudden outbursts from freezing high-pressure water in the coal seam floor of a short working face with gob-side entry retention according to claim 1 is characterized in that: The freezing of the frozen drill holes in the main roadway of the mining area and the mining roadway stops when the frozen drill holes are separated from the mining area of ​​the first mining area by a set distance; The intervals for stopping freezing of frozen drill holes in the main tunnels and return mining tunnels of the mining area are set as follows: when mining in the first mining area, first shut down the freezing operations of all frozen drill holes in the cut-eye tunnel, shut down the freezing operations of frozen drill holes within 20 meters of the cut-eye tunnel in the return mining tunnel of the first mining area, and then use comprehensive mining equipment to advance mining from the cut-eye tunnel to the side of the main tunnel of the mining area. In this process, gradually shut down the freezing operations of frozen drill holes within 20 meters of the coal mining face in the return mining tunnel of the first mining area. The freezing operations in the goaf-retained tunnels of the first mining area do not need to be gradually shut down as the first mining area advances. The freezing operations of the main tunnels of the mining area will be stopped when the freezing equipment is relocated during the mining of the first mining area.

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