Gob-side entry retaining short working face coal seam floor high confined water freezing outburst prevention control method

Abstract

The invention discloses a gob-side entry retaining short working face coal seam floor high confined water freezing outburst prevention control method, and belongs to the technical field of coal underground mining floor water inrush prevention, and the method comprises the following steps: S1, determining process parameters of a freezing method, and detecting coal seam floor high confined water; s2, arranging a first mining area; s3, a freezing chamber is excavated, and freezing equipment is installed; s4, constructing a freezing drill hole extending to the aquifer; s5, a freezing pipeline is installed, and freezing operation is conducted; s6, pumping and draining high-pressure-bearing water of the bottom plate; s7, a hydrological observation drill hole is constructed in a gob-side entry retaining bottom plate; s8, the first working face is subjected to stoping, and a second working face stoping roadway is tunneled; s9, a freezing chamber of the second working face is excavated, and freezing drill holes are constructed; s10, the freezing equipment completes relocation operation before stopping mining on the first working face; and S11, the steps from S5 to S10 are repeated to achieve safe stoping of the working face of the mining area. The device has the advantages that the production efficiency of a mine is improved, and the production safety is guaranteed.

Description

Technical Field

[0002] The 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 water inrush from freezing in coal seam floors of short working faces along gob-side entryways. Background Art

[0004] As mining gradually shifts to deeper areas, the water pressure in the coal seam floor aquifer gradually increases. As a result, water inrush accidents in coal mine floors occur frequently, making the problem of water inrush in the floor one of the major hazards affecting mine safety production.

[0005] At present, the prevention and control of water inrush in mines in my country is mainly focused 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 and controlling limestone water in coal mining floor, Chinese patent CN201610330340.X discloses a method for preventing and controlling water inrush channels when coal mining floor encounters faults, and Chinese patent CN201510297909.2 discloses a method for transforming the floor limestone aquifer into a natural artificial composite complete aquiclude. The above methods are based on the comprehensive exploration of the hydrogeological conditions of the coal mine floor, and implement grouting reinforcement and transformation of the target layer to enhance the integrity and overall strength of the floor aquiclude. The technical defects of this method are that grouting reinforcement cannot completely block the outburst of the floor pressure water, and there is a lack of effective evaluation methods for the grouting effect. In particular, during the mining of the working face, the floor is prone to new water channels due to the influence of dynamic pressure, and the blocked water channels may be connected again.

[0006] Chinese patent CN202110303828.4 discloses a method for preventing water bursts from coal seam floors by freezing high-pressure water. This method uses freezing construction to extract high-pressure water from the floor in 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 water bursts from the floor. Since two mining areas share the same mining tunnel along the goaf, the prevention and control of water bursts from the floor 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.

[0007] Chinese patent CN201410459354.2 discloses a method for analyzing the risk of water inrush from the bottom of a deep well. The method performs weight analysis on multiple factors such as water pressure and water richness of the aquifer, mining height of the working face, mining depth, mining length, ground stress, and mining disturbance, and establishes a theoretical model to predict and analyze the danger of water inrush. This method does not propose specific measures to prevent and control water inrush, and its prediction model lacks sufficient engineering practice as support. The conditions of mines vary greatly and it is difficult to have universal applicability. In addition, some mining areas prevent and control water inrush by reducing mining height, stratified mining, and lane mining. Not only is the prevention and control effect unsatisfactory, but it also reduces the recovery rate of coal resources. Therefore, how to balance the efficient mining of coal resources and the effective prevention and control of water inrush from the bottom is a scientific problem that the coal industry urgently needs to solve. Summary of the invention

[0009] The present invention aims to solve one of the technical problems in the related art at least to a certain extent.

[0010] 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 tunnel left along the goaf. The method for preventing water bursts from freezing in the coal seam floor of a short working face with a tunnel left along the goaf 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.

[0011] The technical solution provided by the present invention is: a method for preventing sudden outbursts from freezing of high-pressure water in the coal seam floor of a short working face along a gob-retained entry, comprising the following steps:

[0012] S1: Determine the process parameters of the freezing method through experiments, and obtain the distribution range and layer position of the high-pressure water on the bottom plate through detection;

[0013] S2: excavating a mining tunnel to one side of the main tunnel of the mining area, excavating a freezing chamber in the mining tunnel, and installing freezing equipment in the freezing chamber. The mining tunnel and the main tunnel of the mining area intersect to form a first mining area. The mining tunnel includes a working face cut-eye tunnel and a gob-side tunnel.

[0014] S3: During the excavation of the mining roadway, multiple freezing boreholes extending to the aquifer are simultaneously constructed in the mining area roadway and the mining roadway, and the multiple freezing boreholes are arranged at set intervals along the mining area roadway or the mining roadway;

[0015] S4: Install a freezing pipeline extending to the aquifer in the freezing borehole, and use freezing equipment to freeze the aquifer under the floor of the main roadway in the mining area and the aquifer under the floor of the recovery roadway;

[0016] 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 of the floor in the area surrounded by the freezing curtain is pumped out by the pumping system;

[0017] S6: Before the first mining area is mined, the freezing operation of the cut-eye roadway is stopped, and a plurality of hydrological observation boreholes are constructed on the bottom plate at the intersection of the cut-eye roadway and the gob-side retained roadway. The plurality of hydrological observation boreholes are inclined toward the first mining area, and the hydrological observation boreholes penetrate the aquifer. The hydrological observation boreholes are used to monitor the time required for water inrush again after freezing stops in the cut-eye roadway;

[0018] S7: Carry out the mining operation and the goaf-retaining tunnel construction operation in the first mining area, and stop freezing the frozen drill holes in the main tunnel of the mining area and the mining tunnel when they are separated by a set distance from the first mining area, until the mining of the first mining area is completed.

[0019] In some embodiments, step S7 also 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.

[0020] 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 along the goaf also includes step S8: before the end of mining in the first mining area, excavating a freezing chamber and constructing freezing drill holes in the mining tunnel of the second mining area.

[0021] In some embodiments, the method for preventing sudden outbursts from freezing high-pressure water in the coal seam floor of a short working face along the gob-retained roadway further includes step S9: determining the timing of relocation of the freezing equipment during the mining of the first mining area and relocating the freezing equipment to the freezing chamber of the second mining area when the mining is stopped in the first mining area, and the moving time T of the freezing equipment satisfies the following formula:

[0022]

[0023] Where: T a T is the mining time of the unmined area in this mining area; b is the additional mining time of the unmined area in this mining area due to geological factors such as faults and structures; L is the mining length of the unmined area in 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 is the mining time of the mined area in this mining area; T1, T2, T3...T N It is used to observe the time of water inrush from the borehole for hydrological observation.

[0024] In some embodiments, the method for controlling high-pressure water freezing in the coal seam floor of a short working face along the goaf also includes step S10: after the freezing equipment is relocated, 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.

[0025] In some embodiments, the strike length of the first mining area does not exceed 800 meters, and the length of the cutting tunnel does not exceed 200 meters.

[0026] In some embodiments, the freezing chamber is arranged in the mining tunnel between the main tunnel of the mining area and the stop mining line of the mining area.

[0027] In some embodiments, 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-fourth of the thickness of the aquifer, the spacing between two adjacent freezing boreholes does not exceed 1.5 meters, the freezing borehole extends in the vertical direction, and the spacing between the freezing borehole and the non-mining side coal wall is not less than 200 mm.

[0028] In some embodiments, 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.

[0029] In some embodiments, the hydrological observation boreholes need to be completed on the day when the freezing operation in the eye-cutting tunnel is stopped, and the hydrological observation boreholes should be approximately parallel to the plane where the freezing boreholes in the eye-cutting 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 serves as the time when the bottom plate aquifer is connected again after the freezing of the eye-cutting tunnel is stopped. The minimum value of the water burst time of all hydrological observation boreholes is one of the references for the timing of relocation of the freezing equipment in the freezing chamber.

[0030] In some embodiments, the frozen drill holes in the main tunnel of the mining area and the recovery tunnel stop freezing when they are at a set interval from the mining area of ​​the first mining area, and the interval setting interval for stopping the freezing of the frozen drill holes in the main tunnel of the mining area and the recovery tunnel is as follows: when recovering in the first mining area, first shut down the freezing operation of all frozen drill holes in the cutting eye tunnel, shut down the freezing operation of the frozen drill holes in the recovery tunnel of the first mining area within 20 meters from the cutting eye tunnel, and then use the comprehensive mining equipment to advance recovery from the cutting eye tunnel to the side of the main tunnel of the mining area. In this process, the freezing operation of the frozen drill holes in the recovery tunnel of the first mining area within 20 meters from the coal mining face is gradually shut down, and the freezing operation in the goaf-retained tunnel of the first mining area does not need to be gradually shut down with the advancement of the first mining area, and the freezing operation of the main tunnel of the mining area will be stopped when the freezing equipment is relocated during the recovery of the first mining area.

[0031] Compared with the prior art, the advantages of the present invention are: (1) after the freezing method is adopted, it is only necessary to pump out the pressurized water in the freezing curtain 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 tunnel, reduce the deformation of the surrounding rock of the bottom plate of the tunnel, and realize safe and efficient production of the mine.

[0032] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a schematic cross-sectional diagram of the freezing arrangement within the mining range of the first mining area of ​​the present invention;

[0035] Figure 2 It is a schematic diagram of the freezing arrangement plan within the mining range of the first mining area of ​​the present invention;

[0036] Figure 3 It is a schematic cross-sectional diagram of the freezing arrangement within the mining range of the second mining area of ​​the present invention;

[0037] Figure 4 It is a schematic diagram of the freezing arrangement plan within the mining range of the second mining area of ​​the present invention;

[0038] In the attached figure: 1. The first mining area; 2. The second mining area; 3. The mining tunnel of the first mining area; 4. The goaf-retained tunnel of the first mining area; 5. The mining tunnel of the second mining area; 6. Frozen boreholes; 7. Frozen curtain; 8. Aquifer; 9. Main tunnel of 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

[0040] The present invention is described in further detail below.

[0041] 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.

[0042] like Figures 1 to 4 As shown, the method for preventing sudden outbursts from freezing high-pressure water 10 in the coal seam floor of the short working face of the first mining area along the gob-retained lane 4 in this embodiment comprises the following steps:

[0043] 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.

[0044] Specifically, the relevant process parameters of the freezing method can be obtained through ground tests. The freezing parameters include the maximum conveying distance of the freezing equipment, the active freezing temperature, the maintenance freezing temperature and the freezing time required for different freezing curtain 7 widths. These freezing parameters can provide a test basis for setting the freezing parameters of the bottom plate high-pressure water 10.

[0045] In addition, it is also necessary to conduct hydrological detection of the high-pressure water 10 in the coal seam floor through detection equipment. The detection methods can be geophysical exploration, tunnel exploration and drilling. Through hydrological detection, the hydrogeological conditions of the high-pressure water 10 in the coal seam floor can be obtained and mastered. Therefore, the distribution range and layer of the high-pressure water 10 can be determined, providing hydrological data for freezing method anti-burst mining.

[0046] S2: excavating a recovery tunnel to one side of the main tunnel 9 of the mining area, excavating a freezing chamber 11 in the recovery tunnel, and installing a freezing device in the freezing chamber 11, wherein the recovery tunnel and the main tunnel 9 of the mining area intersect to form a first mining area 1, and the recovery tunnel includes a working face cut-eye tunnel and a gob-side tunnel 4 of the first mining area;

[0047] Specifically, Figure 1 and Figure 2 As shown, multiple mining areas are arranged on one side of the main tunnel 9 of the mining area, and each mining area adopts the method of leaving a tunnel 4 along the goaf of the first mining area for mining operations, that is, the reserved mining tunnel of the previous mining area can be used as the return air tunnel or transportation tunnel of the next mining area. Therefore, before mining the current mining area (for the convenience of description, the current mining area will also be referred to as the first mining area 1 below), it is only necessary to excavate the mining tunnel on one side of the main tunnel 9 of the mining area, and the first mining area 1 to be mined is between the mining tunnel and the main tunnel 9 of the mining area.

[0048] For example, Figure 1As shown, the first mining area recovery tunnel 3 and the first mining area goaf-retained tunnel 4 are the recovery tunnels of the first mining area 1. When the first mining area 1 is recovered, the goaf-retained tunnel 4 of the first mining area is retained. When the second mining area 2 is mined, the goaf-retained tunnel 4 of the first mining area can be used as the return air tunnel or transport tunnel of the second mining area 2.

[0049] Preferably, during the mining process of the first mining area 1, the gob-side entry 4 of the first mining area can be retained by providing a filling wall 14 in the gob-side entry 4 of the first mining area.

[0050] Specifically, Figure 1 As shown, when the recovery tunnel of the first mining area 1 is excavated, a freezing chamber 11 is excavated in the recovery tunnel 3 of the first mining area and the first mining area along the empty tunnel 4. The freezing chamber 11 can be arranged on a side close to the first mining area 1 or on a side of the next mining area. After the freezing chamber 11 is arranged, the freezing equipment can be installed in the freezing chamber 11.

[0051] 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.

[0052] S3: During the excavation of the recovery tunnel, multiple freezing boreholes 6 extending to the aquifer 8 are simultaneously constructed in the mining area tunnel 9 and the recovery tunnel. The multiple freezing boreholes 6 are arranged at set intervals along the mining area tunnel 9 or the recovery tunnel.

[0053] Specifically, 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 main mining area 9 and the first mining area 1, in the gob-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.

[0054] 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 empty tunnel 4 of the first mining area and the recovery tunnel 3 of the first mining area corresponds to the overall strike length of the first mining area 1.

[0055] Preferably, the multiple freezing 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 freezing 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 freezing drill holes 6 in the empty tunnels 4 of the first mining area are arranged at intervals along the extension direction of the empty tunnels 4 of the first mining area.

[0056] 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 between two adjacent freezing boreholes 6 can be achieved with less energy consumption of the freezing equipment, thereby facilitating the formation of the subsequent freezing curtain 7.

[0057] 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 recovery tunnel.

[0058] Specifically, as all the recovery 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 recovery tunnels 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.

[0059] S5: After the freezing curtain 7 is formed below the first mining area 1, a pumping system is arranged in the mining tunnel and the high-pressure water 10 of the bottom plate in the area surrounded by the freezing curtain 7 is pumped out by the pumping system.

[0060] Specifically, as the freezing operation proceeds, the aquifer 8 between two adjacent freezing boreholes 6 will be frozen through, thereby forming a freezing curtain 7 between any two adjacent freezing boreholes 6. The freezing curtains 7 are connected in series to form a structure similar to an ice wall, thereby playing a role in blocking high-pressure water 10.

[0061] 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, thereby accelerating the formation of the freezing curtain 7.

[0062] The freezing device is kept in the active freezing temperature mode for a set time, for example, 1 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, thereby maintaining the freezing state of the freezing curtain 7, so that the high-pressure water 10 below the first mining area 1 is sealed.

[0063] After the freezing curtain 7 is formed, the high-pressure water 10 in the area surrounded by the freezing curtain 7 (the area below the first mining area 1) can be pumped out by the pumping system. In this way, on the one hand, the high-pressure water 10 below the first mining area 1 can be pumped out in advance, and on the other hand, the water inrush from the bottom plate in the return mining roadway of the first mining area 1 is avoided, thereby improving the safety of the return mining roadway of the first mining area 1 and ensuring the smooth progress of production.

[0064] It should be noted that the detected hydrogeological data can be used to determine the main distribution area of ​​water in the aquifer 8, and then drainage holes can be arranged from the recovery tunnel of the first mining area 1 to this area, and drainage pipelines can be arranged in the drainage holes. Then, the drainage pipelines are connected to the pumping system, thereby realizing the pumping and drainage of high-pressure water 10.

[0065] S6: Before mining in the first mining area 1, stop the freezing operation of the cut-eye tunnel and construct multiple hydrological observation boreholes on the bottom plate at the intersection of the cut-eye tunnel and the gob-retained tunnel. The multiple hydrological observation boreholes are inclined toward the first mining area 1 and penetrate the aquifer. The hydrological observation boreholes are used to monitor the time required for water inrush again after freezing stops in the cut-eye tunnel.

[0066] Specifically, Figure 3 As shown, before the first mining area 1 is officially mined, it is necessary to drill a plurality of hydrological observation boreholes 15 in the gob-side tunnel 4 of the first mining area. The hydrological observation boreholes 15 are inclined toward one side of the first mining area 1, and the hydrological observation boreholes 15 penetrate the aquifer 8 from top to bottom. The high-pressure water 10 under the bottom plate can be monitored through the hydrological observation boreholes 15, so as to know the time from stopping freezing to the next water inrush.

[0067] It should be noted that there may be multiple hydrological observation boreholes 15, such as Figure 4 As shown, the inclination angles of the multiple hydrological observation boreholes 15 can be appropriately changed, so that the high-pressure water 10 in the aquifers 8 at different heights can be monitored.

[0068] In addition, since the hydrological observation borehole 15 is arranged in the goaf-retained tunnel 4 in the first mining area, during the mining process of the first mining area 1, the goaf-retained tunnel 4 in the first mining area needs to be retained and used as the mining tunnel of the second mining area 2. Therefore, the monitoring of the hydrological observation borehole 15 will not be affected by the mining of the first mining area 1, and the effective monitoring of the hydrological observation borehole 15 can continue until the end of mining in the first mining area 1.

[0069] S7: Carry out the mining operation of the first mining area 1 and the construction operation of the goaf-retaining lane 4 in the first mining area, and stop freezing the frozen drill holes in the main lane 9 of the mining area and in the mining lane when they are separated by a set distance from the first mining area 1, and continue until the mining of the first mining area 1 is completed.

[0070] Specifically, Figure 2 As shown, when mining in the first mining area 1, it is necessary to first shut down the freezing pipeline 13 in the eye-cutting tunnel and the freezing pipeline 13 in the mining tunnel 3 of the first mining area, which is 20 meters away from the eye-cutting tunnel. Then, the comprehensive mining equipment can be used to advance mining from the eye-cutting tunnel to the side of the main tunnel 9 of the mining area.

[0071] It should be noted that the freezing pipeline 13 in the gob-side tunnel 4 of the first mining area does not need to be gradually shut down as the first mining area 1 advances.

[0072] In some embodiments, step S7 also includes, while the first mining area 1 is being mined, excavating the mining tunnel of the second mining area 2 on the other side of the mining area main tunnel 9, and the mining tunnel of the first mining area 1 is reserved and used as the gob-side tunnel of the second mining area 2.

[0073] Specifically, Figure 4 As shown, during the mining process of the first mining area 1, the mining roadway (the second mining area mining roadway 5) of the next mining area (the second mining area 2) can be arranged in advance. After the mining of the first mining area 1, the gob-side roadway 4 of the first mining area can be converted into a reserved roadway of the second mining area 2. In this way, the mining efficiency can be improved and the boundary time of the working face can be shortened.

[0074] 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-retained tunnel 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 drill hole 6 is constructed in the mining tunnel 5 of the second mining area 2.

[0075] Specifically, 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.

[0076] In some embodiments, 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 further includes step S9: determining the timing of relocation of the freezing equipment during the mining of the first mining area 1 and relocating the freezing equipment to the freezing chamber 11 of the second mining area 2 when the mining is stopped in the first mining area 1, and the moving time T of the freezing equipment satisfies the following formula:

[0077]

[0078] Where: T a T is the mining time of the unmined area in this mining area (d); bis the mining time (d) increased by the unmined area in this mining area due to geological factors such as faults and structures; L is the mining length of the unmined area in 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 The protective coal pillar between the stop mining line 12 and the main tunnel 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 (d) of hydrological observation borehole 15.

[0079] Specifically, Figure 4 As shown, before the first mining area 1 is almost finished, the freezing chamber 11 can be excavated in the mining tunnel 5 of the second mining area 2, and then the freezing operation of the freezing chamber 11 in the mining tunnel 3 of the first mining area 1 can be completely stopped, and the freezing equipment of the freezing chamber 11 in the mining tunnel 3 of the first mining area 1 can be moved to the freezing chamber 11 of the mining tunnel 5 of the second mining area 2. In this way, the boundary time of the working face can be further reduced and the production efficiency of the mine can be improved.

[0080] 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.

[0081] In addition, the moving time of the freezing equipment should also match the length of the unmined coal wall in the first mining area 1, that is, whether to start moving the freezing equipment can be determined by measuring the length of the unmined coal wall in the first mining area 1. That is, it is necessary to ensure that the evacuation of the freezing equipment is completed before the mining area advances to the stop mining line 12.

[0082] In some embodiments, the method for controlling freezing of high-pressure water 10 in the floor of the coal seam in the short working face along the goaf 3 to prevent sudden coal outbursts also includes step S10: after the relocation of the freezing equipment is completed, a freezing curtain of 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.

[0083] Specifically, 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.

[0084] In some embodiments, the length of the mining tunnel does not exceed 800 meters, and the length of the cut-eye tunnel does not exceed 200 meters. Specifically, the mining tunnel can be the first mining tunnel 4 or the second mining tunnel 5, and the mining tunnel can be 500 meters, 600 meters, 700 meters, 800 meters, etc. The length of the cut-eye tunnel is the length of the mined coal wall of the working face, and the length of the cut-eye tunnel can be 100 meters, 150 meters, 200 meters, etc. In this way, the freezing effect of the freezing curtain 7 can be guaranteed, and the situation that the working face is too large and it is not easy to freeze can be avoided.

[0085] 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.

[0086] Specifically, Figure 4 As shown, the freezing chamber 11 is arranged in the tunnel between the main tunnel 9 and the stop mining line 12 of the mining area. Since the coal pillar is protected here, the freezing chamber 11 is less disturbed and will not affect the evacuation of the freezing equipment.

[0087] In some embodiments, the freezing borehole 6 passes through the aquifer 8 at the bottom of the coal seam, and the length of the freezing borehole 6 beyond the aquifer 8 is not less than one-fourth 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.

[0088] Specifically, Figure 1 and Figure 2 As shown, the freezing borehole 6 can be arranged to extend vertically in the up-down direction, and the freezing borehole 6 can pass through the aquifer 8. The length of the freezing borehole 6 passing through the aquifer 8 should be no less than one-fourth 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 to ensure the freezing effect.

[0089] The freezing borehole 6 is arranged at a position of the roadway away from the coal wall of the first mining area 1, and the spacing between the freezing borehole 6 and the non-mining side coal wall can be 200 mm, 250 mm, etc. Thus, the influence of mining on the freezing borehole 6 can be avoided, which is conducive to prolonging the freezing time.

[0090] 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 the safe recovery of the working face.

[0091] In some embodiments, the frozen drill holes in the mining tunnel of the previous working face can continue to be used as the frozen drill holes in the gob-side retaining tunnel of the next working face, thereby reducing the construction volume of the frozen drill holes and further reducing the mining cost.

[0092] In some embodiments, the hydrological observation borehole 15 needs to be completed on the day when the freezing operation in the eye-cutting tunnel is stopped, and the hydrological observation borehole 15 should be approximately parallel to the plane where the freezing borehole 6 in the eye-cutting tunnel is located and constructed close to the plane. The time from the completion of the hydrological observation borehole 15 to the time when water bursts again in the hole serves as the time when the bottom plate aquifer 8 is connected again after the eye-cutting tunnel stops freezing. The minimum value of the water burst 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.

[0093] In some embodiments, the frozen drill holes 6 in the main tunnel 9 of the mining area and in the recovery tunnel stop freezing when they are at a set interval from the mining area interval of the first mining area 1, and the interval setting interval for stopping the freezing of the frozen drill holes 6 in the main tunnel 9 of the mining area and the recovery tunnel is as follows: when recovering in the first mining area 1, first shut down the freezing operation of all frozen drill holes 6 in the cutting eye tunnel, shut down the freezing operation of the frozen drill holes 6 in the recovery tunnel of the first mining area 1 within 20 meters from the cutting eye tunnel, and then use the comprehensive mining equipment to recover and advance from the cutting eye tunnel to the side of the main tunnel 9 of the mining area. In this process, the freezing operation of the frozen drill holes 6 in the recovery tunnel of the first mining area 1 within 20 meters from the coal mining working face is gradually shut down, and the freezing operation in the goaf-retained tunnel 4 of the first mining area 1 does not need to be gradually shut down with the advancement of the first mining area 1, and the freezing operation of the main tunnel 9 of the mining area is stopped when the freezing equipment is relocated during the recovery of the first mining area 1.

[0094] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means 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 may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0095] Although the 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 present invention, and that the scope of the present 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 along the gob-retained 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 on the bottom plate through detection; S2, excavating a mining tunnel to one side of the main tunnel of the mining area, excavating a freezing chamber in the mining tunnel, and installing freezing equipment in the freezing chamber, wherein the mining tunnel and the main tunnel of the mining area intersect to form a first mining area, and the mining tunnel includes a working face cut-eye tunnel and a gob-side retained tunnel; S3. During the excavation of the mining roadway, multiple freezing boreholes extending to the aquifer are simultaneously constructed in the mining area roadway and the mining roadway, and the multiple freezing boreholes are arranged at set intervals along the mining area roadway or the mining roadway; S4. Install a freezing pipeline extending to the aquifer in the freezing borehole, and use freezing equipment to freeze the aquifer under the floor of the main roadway in the mining area and the aquifer under the floor of the recovery 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 of the floor in the area surrounded by the freezing curtain is pumped out by the pumping system; S6. Before the first mining area is mined, the freezing operation of the cut-eye roadway is stopped, and a plurality of hydrological observation boreholes are constructed on the floor at the intersection of the cut-eye roadway and the gob-side roadway. The plurality of hydrological observation boreholes are inclined toward the first mining area, and the hydrological observation boreholes penetrate the aquifer. The hydrological observation boreholes are used to monitor the time required for water inrush again after freezing stops in the cut-eye roadway; S7. Carry out the mining operation and the goaf-retaining lane 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 at a set distance from the mining area of ​​the first mining area, and continue until the mining of the first mining area is completed.

2. The method for preventing sudden outbursts from freezing of high-pressure water in the coal seam floor of a short working face along the gob-side entry 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 of high-pressure water in the coal seam floor of a short working face along the gob-side entry according to claim 2 is characterized by: The method further comprises step S8, excavating a freezing chamber and constructing freezing boreholes in the mining tunnel of the second mining area before the mining of the first mining area is completed.

4. The method for preventing sudden outbursts from freezing of high-pressure water in the coal seam floor of a short working face along the gob-side entry according to claim 3 is characterized by: The method further includes step S9, determining the time for relocating the freezing equipment during the mining period of the first mining area and relocating the freezing equipment to the freezing chamber of the second mining area before the mining of the first mining area is stopped, and 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 additional mining time of the unmined area in this mining area due to geological factors such as faults and structures; L is the mining length of the unmined area in 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 is the mining time of the mined area in this mining area; T1, T2, T3...T N It is used to observe the time of water inrush from the borehole for hydrological observation.

5. The method for preventing sudden outbursts from freezing of high-pressure water in the coal seam floor of a short working face along the gob-side entry according to claim 4 is characterized by: The method also includes step S10, after the freezing equipment relocation work is completed, constructing an aquifer freezing curtain 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 recovering the second mining area, repeating the above steps S6 to S9 until the recovery of all mining areas is completed.

6. The method for preventing sudden outbursts from freezing of high-pressure water in the coal seam floor of a short working face along a gob-side entry 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 cutting tunnel does not exceed 200 meters.

7. The method for preventing sudden outbursts from freezing of high-pressure water in the coal seam floor of a short working face along a gob-side entry 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.

8. The method for preventing sudden outbursts from freezing of high-pressure water in the coal seam floor of a short working face along a gob-side entry according to claim 1 is characterized in that: The freezing borehole passes through the aquifer at the bottom of the coal seam, 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 is not more than 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.

9. The method for preventing sudden outbursts from freezing of high-pressure water in the coal seam floor of a short working face along a gob-side entry 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.

10. The method for preventing sudden outbursts from freezing of high-pressure water in the coal seam floor of a short working face along a gob-retained entry 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 eye-cutting tunnel is stopped, and the hydrological observation boreholes should be approximately parallel to the plane where the freezing boreholes in the eye-cutting 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 freezing of the eye-cutting tunnel is stopped. The minimum value of the water burst time of all hydrological observation boreholes is one of the references for the timing of relocation of the freezing equipment in the freezing chamber.

11. The method for preventing sudden outbursts from freezing of high-pressure water in the coal seam floor of a short working face along a gob-side entry according to claim 1 is characterized in that: The freezing of the frozen boreholes in the main lane of the mining area and the recovery lane stops when the freezing boreholes are separated from the mining area of ​​the first mining area by a set distance; The interval setting interval for stopping freezing of frozen drill holes in the main tunnel and recovery tunnel of the mining area is as follows: when recovering in the first mining area, first shut down the freezing operation of all frozen drill holes in the cutting tunnel, shut down the freezing operation of frozen drill holes within 20 meters of the cutting tunnel in the recovery tunnel of the first mining area, and then use the comprehensive mining equipment to recover and advance from the cutting tunnel to the side of the main tunnel of the mining area. In this process, gradually shut down the freezing operation of frozen drill holes within 20 meters of the coal mining face in the recovery tunnel of the first mining area. The freezing operation in the goaf-retained tunnel of the first mining area does not need to be gradually shut down as the first mining area advances. The freezing operation of the main tunnel of the mining area will be stopped when the freezing equipment is relocated during the recovery of the first mining area.

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