A coal mine roadway driving method for preventing rock burst based on the freezing method of fault rich confined water

Abstract

The present invention discloses a method for driving a coal mine roadway to prevent rock burst based on the freezing method of rich confined water in a fault zone, which includes an advanced geological exploration stage and a step-by-step construction stage of freezing boreholes. The advanced geological exploration stage includes detecting the properties of the fault and the occurrence conditions of high-confined water. In the step-by-step construction stage of freezing boreholes, pipelines are connected to the freezing construction boreholes, and the rich confined water around the fault fracture zone is frozen by using low temperature. The frozen areas on both sides of the fault exceed 25 m beyond the two wings of the fault fracture zone. After freezing is completed, the tunnel face is driven forward, and at the same time, the freezing temperature of the freezing construction boreholes is monitored and the freezing effect is maintained. After driving through the fault fracture zone for 50 - 70 m, the freezing is stopped and it is allowed to thaw naturally. It can well solve the risk of rock burst faced in the driving of coal mine roadways in the geological conditions of rich water near faults. This method has good water isolation performance, strong adaptability to the formation, convenient construction, and is conducive to solving the problem of sudden water inrush from faults during roadway driving.

Description

Technical Field

[0001] The present invention belongs to the technical field of coal mining, and in particular relates to a coal mine anti-rock pressure excavation method based on a fault rich confined water freezing method. Background Art

[0002] With the continuous increase in the depth and intensity of coal mining in my country, mine rock burst accidents have gradually become one of the major disasters affecting safe mining. During tunneling and coal mining, the presence of faults exacerbates the instability of the coal rock mass, and coal mine rock bursts and strong mine earthquakes caused by fault activity occur frequently. For deep hydrogeological areas rich in confined water, mining disturbances can easily cause fault activation, thereby increasing the risk of mine water inrush and rock bursts in tunnels. Therefore, how to prevent and control rock burst accidents during coal mine tunneling, especially to carry out safe and efficient excavation in geological environments rich in confined water near faults, has become a key issue that urgently needs to be studied and resolved for the green development of the mining industry.

[0003] Due to the broken rock mass and poor water resistance in the fault fracture zone, tunnel excavation through a fault rich in pressurized water will cause dynamic disturbances, resulting in mine water inrush, fault instability activation, and rock burst pressure, among other safety risks. Existing construction technologies such as surface drainage, underground drainage, and pressurized mining have some shortcomings. For example, changes in the water pressure of pressurized water can easily destroy the stress balance of the fault structural zone, induce fault activation-type rock burst pressure, and open up pressurized water fissure channels. Therefore, it is necessary to study a safe and reliable construction method that can be used for preventing and controlling rock burst pressure during tunnel excavation in coal mine fault areas rich in pressurized water. Summary of the Invention

[0004] To address the aforementioned challenges of the existing technologies, the present invention provides a method for preventing and controlling rock bursts in coal mine tunneling based on the freezing of rich confined water in fault zones. This method effectively addresses the rock burst risks faced by coal mine tunneling in water-rich, near-fault geology. This method offers excellent water-blocking properties, strong adaptability to strata, and ease of construction. It also helps address the problem of sudden water inrush from fault zones during tunneling.

[0005] The present invention achieves the above-mentioned purpose through the following technical solutions:

[0006] A coal mine anti-rock burst tunneling method based on the fault rich confined water freezing method specifically includes an advance geological exploration stage and a freezing drilling step-by-step construction stage.

[0007] The fault in the construction method refers to a ductile mode fault, which includes a fault plane and a fracture zone. Under the influence of external factors, such as rich pressurized water, the upper plate and the lower plate may undergo relative slip and displacement along the fault plane, and form a fracture zone with a certain influence depth.

[0008] In the advanced geological exploration stage, it includes the detection of the fault characteristics and the occurrence conditions of high-confined water. The specific implementation process is as follows:

[0009] S1: Implement multiple advanced exploration boreholes near the fault plane in the underground roadway driving area to determine the occurrence, geometric dimensions, mechanical properties, etc. of the fault, explore the layer position and regional boundary of the high-confined water in the fault, and determine the layout spacing, quantity, angle and other freezing hole layout parameters of the freezing method boreholes according to the exploration results;

[0010] S2: According to the freezing hole layout parameters determined in step S1 and the high-confined water content and boundary in the fault, determine the action time and temperature of the freezing boreholes.

[0011] Combined with Figure 3 , after the advanced geological exploration is completed, the step-by-step construction stage of the freezing boreholes in the embodiment of the present invention mainly includes the following steps:

[0012] S(3): By connecting the external constant temperature pipeline to the freezing construction borehole, the rich-confined water around the fault can be frozen by using low temperature. The frozen areas on both sides of the fault generally exceed the broken zone, including the distal broken zone and the proximal broken zone, more than 25m on both wings, so as to isolate the high-confined water area in the fault from the driving area, prevent the activation of the fault during the disturbance process of roadway driving, and thus avoid the occurrence of the fault activation impact ground pressure disaster.

[0013] S4: After the freezing is completed, the heading face is ready to drive. At the same time, monitor the freezing temperature of the freezing construction borehole and maintain the freezing effect. 50-70m after the driving face passes through the distal fault broken zone, stop maintaining the freezing holes and let them thaw naturally.

[0014] Furthermore, in the step-by-step construction stage of the freezing boreholes, the proximal broken zone area can be frozen first at the crown and invert of roadway 1 by using the construction freezing borehole Ⅰ; after the freezing temperature is stable, further extend the borehole and freeze the area through the fault plane by using the construction freezing borehole Ⅱ; finally, wait for the freezing temperature to be further stable, further extend the borehole, and freeze the distal broken zone by using the construction freezing borehole Ⅲ, so as to complete the construction of the whole process.

[0015] Furthermore, along the longitudinal section of the roadway axis, the first borehole (with a length of 30m) is drilled vertically at the crown and invert positions of the freezing construction borehole. If the freezing influence radius of the freezing borehole is taken as 3m, the layout parameters of other boreholes can be calculated according to formulas (1) and (2)

[0016]

[0017]

[0018] Wherein, n is the number of borehole arrangements (n = 1, 2, 3, …, i), and θ n is the vertical angle when arranging the nth borehole, and L n is the length of the nth borehole.

[0019] Furthermore, the arrangement of freezing construction boreholes in the plane includes a borehole group along the tunneling direction at the crown and invert positions respectively, and a borehole group with a certain inclination angle in the horizontal direction.

[0020] Furthermore, the freezing temperature of the freezing holes is not lower than -35°C, the freezing time is not less than 15 days, and the freezing maintenance temperature is not lower than -25°C.

[0021] The beneficial effects of the present invention are as follows:

[0022] A coal mine rockburst prevention tunneling method based on the freezing method for rich confined water in faults of the present invention, through the reasonable arrangement of freezing boreholes near the faults in the tunneling roadway, can not only freeze the high-confined water in the faults to inhibit the occurrence of roadway water inrush, but also avoid the coal mine rockburst disasters caused by fault activation by reducing the change and influence on the fault state, and can ensure the operation safety of construction personnel to the greatest extent, and has the characteristics of low economic cost and high safety. Description of the Drawings

[0023] Figure 1 is a schematic diagram of the ductile mode fault structure of the embodiment of the present invention;

[0024] Figure 2 is a longitudinal sectional view of the advanced borehole exploration of the tunneling roadway in the embodiment of the present invention;

[0025] Figure 3 is a construction process diagram of the freezing method for rich confined water in faults in the embodiment of the present invention;

[0026] Figure 4 is a longitudinal sectional view of the freezing construction borehole arrangement in the embodiment of the present invention;

[0027] Figure 5 is a schematic plan view of the freezing construction borehole arrangement in the embodiment of the present invention.

[0028] 1 - roadway, 2 - fault plane, 3 - fracture zone, 31 - distal fracture zone, 32 - proximal fracture zone, 4 - high-confined water in the fault, 5 - advanced exploration borehole, 6 - freezing construction borehole, 61 - freezing construction borehole I, 62 - freezing construction borehole II, 63 - freezing construction borehole III, 7 - roadway axis, 8 - hanging wall, 9 - footwall. Detailed Embodiments

[0029] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0030] A coal mine anti-rock burst tunneling method based on the fault rich confined water freezing method specifically includes an advance geological exploration stage and a freezing drilling step-by-step construction stage.

[0031] Combine Figure 1 The fault in the construction method refers to a ductile mode fault. The ductile mode fault in the embodiment of the present invention includes a fault plane and a fracture zone. Under the influence of external factors (such as rich pressurized water), the upper plate 8 and the lower plate 9 can undergo relative slip and displacement along the fault plane and form a fracture zone with a certain influence depth.

[0032] Combine Figure 2 The advanced geological exploration stage of the embodiment of the present invention includes the detection of fault characteristics and highly confined water storage conditions. The specific implementation process is as follows:

[0033] S1: Conduct multiple advance exploration drilling holes 5 near the fault surface 2 in the excavation area of the underground tunnel 1 to determine the occurrence, geometric dimensions, and mechanical properties of the fault, and to explore the position and regional boundaries of the high-pressure water 4 of the fault. Based on the exploration results, determine the layout parameters of the freezing holes, such as the spacing, number, and angle of the freezing holes.

[0034] S2: Determine the freezing drilling time and temperature based on the freezing hole arrangement parameters determined in step S1 and the fault high confined water 4 content and boundary.

[0035] Combine Figure 3 After completing the advanced geological exploration, the freeze drilling step-by-step construction phase of the embodiment of the present invention mainly includes the following steps:

[0036] S3: By connecting the external constant temperature pipe to the freezing construction borehole 6, the high-pressure water around the fault can be frozen by low temperature. The frozen area on both sides of the fault generally exceeds 50m on both sides of the fracture zone (including the distal fracture zone 31 and the proximal fracture zone 32), thereby isolating the high-pressure water 4 area of the fault from the excavation area to prevent fault activation during the excavation disturbance of the tunnel 1, thereby avoiding the occurrence of impact ground pressure disasters induced by fault activation.

[0037] S4: After the freezing is completed, the tunnel face is ready for excavation. At the same time, the freezing temperature of the frozen construction borehole 6 is monitored and the freezing effect is maintained. 50-70m after the excavation face passes through the distal fault fracture zone 31, the maintenance of the frozen hole is stopped and it is allowed to melt and thaw naturally.

[0038] Furthermore, Figure 3 In the step-by-step construction stage of the freezing boreholes described in (a)-(c), the proximal fractured zone 32 can be frozen first at the crown and invert of roadway 1 by using the construction freezing borehole I 61; after the freezing temperature stabilizes, the borehole can be further extended, and the fault plane 2 can be frozen by using the construction freezing borehole II 62; finally, waiting for the freezing temperature to further stabilize, the borehole can be further extended, and the distal fractured zone 31 can be frozen by using the construction freezing borehole III 63, thus completing the construction of the whole process.

[0039] Furthermore, in combination with Figure 4 , along the longitudinal section of the roadway axis 7, the first borehole (with a length of 30 m) is drilled vertically at the crown and invert positions of the freezing construction borehole 6. If the freezing influence radius of the freezing borehole is taken as 3 m, the layout parameters of other boreholes can be calculated according to formulas (1) and (2).

[0040]

[0041]

[0042] In the formula, n is the number of borehole layouts (n = 1, 2, 3,..., i), θ n is the vertical angle when arranging the nth borehole, and L n is the length of the nth borehole.

[0043] Even further, in combination with Figure 5 , the layout of the freezing construction borehole in the plane includes a borehole group along the driving direction at the crown and invert positions respectively and a borehole group with a certain inclination angle in the horizontal direction.

[0044] Even further, the freezing temperature of the freezing holes is not lower than -35 °C, the freezing time is not less than 15 days, and the freezing maintenance temperature is not lower than -25 °C.

[0045] In summary, a coal mine rockburst prevention tunneling method based on the freezing method for rich confined water in faults of the present invention, through the reasonable layout of freezing boreholes near the faults of the tunneling roadway, can not only freeze the high-confined water in the faults to inhibit the occurrence of roadway water inrush, but also avoid the coal mine rockburst disasters caused by fault activation by reducing the change and influence on the fault state, and can ensure the operation safety of construction personnel to the greatest extent, and has the characteristics of low economic cost and high safety.

[0046] The above-described embodiments are the preferred embodiments of the present invention, which are only used to conveniently illustrate the present invention and do not impose any formal restrictions on the present invention. Any person with ordinary knowledge in the technical field concerned, without departing from the technical features of the present invention, makes equivalent embodiments with partial modifications or decorations using the technical content disclosed in the present invention, and without departing from the technical feature content of the present invention, still fall within the scope of the technical features of the present invention.

Claims

1. A coal mine roadway driving method for preventing rock bursts based on the freezing method of rich confined water in a fault. The fault refers to a ductile mode fault, including a fault plane and a fracture zone, and is characterized in that, The excavation method includes an advanced geological exploration stage and a frozen drilling step-by-step construction stage. The advanced geological exploration stage includes detecting fault characteristics and high-pressure water conditions. In the frozen drilling step-by-step construction stage, a pipeline is connected to the frozen construction borehole, and the pressurized water around the fault fracture zone is frozen using low temperature. The frozen area on both sides of the fault exceeds 25 meters on both sides of the fault fracture zone. After freezing is completed, the tunnel face is excavated while the freezing temperature of the frozen construction borehole is monitored and the freezing effect is maintained. After excavating through the fault fracture zone for 50-70 meters, the freezing is stopped and allowed to thaw naturally. The spacing, number, and angle of the freezing hole arrangement parameters for the freezing method are determined based on the exploration results. Along the longitudinal section of the roadway axis, the first hole is drilled vertically at the arch top and arch bottom, with a length of L meters. The freezing influence radius of the freezing hole is A meters. The arrangement parameters of other holes can be calculated according to formulas (1) and (2): where n is the number of borehole arrangements, n = 1, 2, 3, …, i; θ n is the vertical angle when arranging the nth borehole, L n is the length of the nth borehole; The freezing drilling is carried out in a step-by-step construction stage. First, the proximal crushing zone is frozen at the arch top and arch bottom of the tunnel using the construction freezing drilling hole I; after the freezing temperature stabilizes, the drilling hole is further extended, and the fault plane area is frozen using the construction freezing drilling hole II; finally, after the freezing temperature further stabilizes, the drilling hole is further extended, and the distal crushing zone is frozen using the construction freezing drilling hole III.

2. The coal mine rock burst prevention tunneling method based on the frozen method for fault rich confined water according to claim 1, characterized in that, The implementation steps of the advanced geological exploration stage are: implementing a number of advanced exploration drilling holes near the fault surface in the underground tunnel excavation area to determine the occurrence, geometric dimensions and mechanical properties of the fault, and to explore the layers rich in pressurized water and the regional boundaries.

3. The coal mine rock burst prevention tunneling method based on the freezing method for fault rich confined water according to claim 2, characterized in that, The arrangement of the drill holes in the plane includes drill hole groups at the arch top and arch bottom positions along the excavation direction and drill hole groups with several inclination angles in the horizontal direction.

4. The coal mine rock burst prevention tunneling method based on the frozen method for fault rich confined water according to claim 1, characterized in that, The freezing temperature is not lower than -35°C, the freezing time is not less than 15 days, and the freezing maintenance temperature is not lower than -25°C.

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