Rapid water inrush point plugging method for coal mine roadway

Abstract

The present application relates to the field of mining engineering. Disclosed is a rapid water inrush point plugging method for a coal mine roadway. The method comprises: determining the location of a water inrush point; determining a plugging point of a coal mine roadway on the basis of the location of the water inrush point; drilling a plugging exploration hole from the ground to the plugging point to acquire a core of a roadway roof; determining a roadway height revealed by the plugging exploration hole, and acquiring a water flow velocity; determining the distribution length of a group of plugging boreholes; drilling the group of plugging boreholes; performing in-borehole hydraulic fracturing at a distance of x above the roadway roof exposed by the group of plugging boreholes; grouting fractures generated by the hydraulic fracturing; drilling a group of grouting boreholes from the ground to a coal mine roadway region exposed by the group of plugging boreholes; performing combined in-borehole blasting at a distance of x above the roadway roof exposed by the group of plugging boreholes; and drilling a group of grouting boreholes from the ground to the coal mine roadway region exposed by the group of plugging boreholes, drilling to the floor of the roadway, and performing grouting. The present application can improve the efficiency of plugging a water inrush point of a coal mine roadway and reduce costs.

Description

A method for rapid interception of water inrush points in coal mine roadways Technical Field

[0001] This application relates to the field of mining engineering technology, and in particular to a method for rapid interception of water inrush points in coal mine roadways. Background Technology

[0002] Coal mining is susceptible to various disasters, among which mine water inrush is a significant one. Mine water inrushes typically occur at the coal face, flooding the entire mine shaft through the roadways and causing substantial economic losses and casualties. Therefore, the first step in controlling mine water inrushes or restoring production is to rapidly intercept water inrush points in the mine roadways.

[0003] Traditional rapid interception methods have the following problems: (1) Grouting at the water inrush point is difficult, especially in mines with large water inflow. (2) Using chemically accelerated grout for grouting and sealing causes environmental pollution. (3) Due to the large flow rate, a large number of grouting boreholes are required. Therefore, the grouting and sealing process takes a long time. (4) The sealing effect after interception is not good, and secondary disasters may occur. (5) The large amount of grouting results in high economic costs. Summary of the Invention

[0004] The purpose of this application is to provide a method for rapid interception of water inrush points in coal mine roadways, which can improve the efficiency of water inrush point interception and reduce costs.

[0005] To achieve the above objectives, this application provides the following solution:

[0006] This application provides a method for rapid interception of water inrush points in coal mine roadways, the method comprising:

[0007] The location of the water inrush point can be determined by identifying the point where the water volume in the tunnel drainage ditch increases.

[0008] Determine the interception point of the coal mine roadway based on the location of the water inrush point;

[0009] Cut-off exploration holes are drilled from the ground to the cut-off point to obtain rock cores from the tunnel roof, and the fragmentation coefficient of the tunnel roof rock cores is determined based on the rock cores.

[0010] Determine the height of the tunnel revealed by the interception exploration hole and obtain the water flow velocity;

[0011] The distribution length of the cutoff borehole group is determined based on the tunnel height, the tensile strength of the material after the crushed rock core of the tunnel roof is mixed with cement, and the equivalent pressure determined by the water flow velocity.

[0012] Starting from the interception point, the implementation range is defined by the distribution length of the interception borehole group, and the spacing between the interception boreholes is defined by a set distance. The interception borehole group is implemented along the direction of the roadway.

[0013] Hydraulic fracturing was performed in the borehole at a distance x above the exposed roadway roof by the cut-off borehole group.

[0014] Grouting is performed on the fractures created by hydraulic fracturing.

[0015] Grouting boreholes are carried out in the coal mine roadway area exposed by the intercepting boreholes on the ground.

[0016] At a distance x above the roadway roof revealed by the cut-off borehole group, a combined borehole blasting is carried out until the rock mass within x range above the coal mine roadway detaches from the strata and reaches the roadway.

[0017] In the coal mine roadway area exposed by the surface interception borehole group, grouting borehole group is carried out to drill to the bottom plate of the roadway and grouting is performed.

[0018] Complete the sealing of the water inrush point.

[0019] In one embodiment, determining the distribution length of the cutoff borehole group based on the roadway height, the tensile strength of the material after mixing the crushed rock core from the roadway roof with cement, and the equivalent pressure determined by the water flow velocity specifically includes:

[0020] Using formula Determine the distribution length L of the cutoff borehole group;

[0021] Where K is the safety factor, h is the tunnel height, and K p ρ represents the tensile strength of the material obtained by mixing the crushed rock core from the tunnel roof with cement, and p represents the equivalent compressive strength. ρ is the density of water, and v is the velocity of the water flow.

[0022] In one embodiment, the distance x above the tunnel roof exposed by the cutoff borehole group is determined using the formula x = (h / a) + 2; where a is the fragmentation coefficient of the tunnel roof rock core.

[0023] In one embodiment, the hydraulic fracturing pressure is greater than the confining pressure.

[0024] In one embodiment, the injected slurry is a mixture of bentonite, glutinous rice paste and water.

[0025] In one embodiment, the solid-liquid ratio of bentonite, glutinous rice paste and water is 2:1 to 3:1, and the mass ratio of bentonite and glutinous rice paste is 1:1 to 3:1.

[0026] In one embodiment, the number of boreholes in the grouting borehole group is the same as the number of boreholes in the cutoff borehole group.

[0027] In one embodiment, the implementation of grouting boreholes in the coal mine roadway area exposed by the ground-facing intercepting borehole group, drilling to the roadway floor and grouting there, specifically includes:

[0028] The injection volume W is determined using the formula W = c × x × L × d;

[0029] Where c is the safety factor, x is the distance x above the roadway roof exposed by the cutoff borehole group, d is the roadway width, and L is the distribution length of the cutoff borehole group.

[0030] According to the specific embodiments provided in this application, the following technical effects are disclosed:

[0031] This application provides a method for rapid interception of water inrush points in coal mine roadways. Starting from the interception point, the method utilizes the length of the interception borehole group distribution as the implementation range, with a predetermined distance as the borehole spacing, and implements the interception borehole group along the roadway direction. Hydraulic fracturing is performed within the boreholes at a distance x above the roadway roof exposed by the interception borehole group, followed by grouting. Then, borehole blasting causes the rock mass of the roadway roof to fracture and expand, sealing the coal mine roadway and achieving rapid sealing. Furthermore, the distribution length of the interception borehole group takes into account the roadway height, the tensile strength of the mixture of fractured rock fragments and cement from the roadway roof core, and the equivalent pressure determined by the water flow velocity, thereby achieving the purpose of safety protection. After the combined borehole blasting, grouting is performed again, making it easier and faster to fill the roadway, achieving the purpose of rapid interception. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 is a flowchart illustrating a method for rapid interception of water inrush points in coal mine roadways according to an embodiment of this application. Detailed Implementation

[0034] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0035] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0036] In an exemplary embodiment, as shown in FIG1, a method for rapid interception of water inrush points in coal mine roadways is provided, the method comprising the following steps S101 to S112. Wherein:

[0037] S101, the location of the water inrush point is determined by the point where the water volume in the tunnel drainage ditch increases.

[0038] S102, determine the interception point of the coal mine roadway based on the location of the water inrush point.

[0039] Specifically, the interception point of a coal mine roadway is the point downstream of the water inrush point and, within the roadway area of ​​the water inrush point, the closest point to the surface. The roadway area of ​​the water inrush point is the space excavated from the roadway.

[0040] S103, conduct a cutoff exploration hole from the ground to the cutoff point to obtain the tunnel roof rock core, and determine the fragmentation coefficient of the tunnel roof rock core based on the tunnel roof rock core.

[0041] S104, determine the height of the tunnel revealed by the interception exploration hole and obtain the water flow velocity.

[0042] S105, the distribution length of the cutoff borehole group is determined based on the tunnel height, the tensile strength of the material after mixing the crushed rock core from the tunnel roof with cement, and the equivalent pressure determined by the water flow velocity; the mixing ratio of the crushed rock core from the tunnel roof with cement is 1:1, the water-cement ratio of cement is 1:1 to 1:2, and it contains 5% to 10% quick-setting agent.

[0043] Using formula Determine the distribution length L of the cutoff borehole group.

[0044] Where K is the safety factor, h is the tunnel height, and K p ρ represents the tensile strength of the material obtained by mixing the crushed rock core from the tunnel roof with cement, and p represents the equivalent compressive strength. ρ is the density of water, and v is the velocity of the water flow.

[0045] S106, starting from the interception point, with the distribution length of the interception borehole group as the implementation range, and with a set distance as the spacing between the interception boreholes, the interception borehole group is implemented along the direction of the roadway; the set distance is 2 to 5 meters.

[0046] All the cutoff boreholes are vertical holes, drilled into the roof of the roadway. The cutoff borehole group is constructed from the ground, and the final hole is located downstream of the water inrush point in the roadway.

[0047] S107, hydraulic fracturing is performed at a distance x above the tunnel roof exposed by the cutoff borehole group; x = (h / a) + 2, where a is the fragmentation coefficient of the tunnel roof core. The hydraulic fracturing pressure is greater than the confining pressure and is continued until the hydraulic connection between adjacent boreholes is achieved.

[0048] S108 is used for grouting cracks caused by hydraulic fracturing.

[0049] The injected grout is a mixture of bentonite, glutinous rice paste, and water; the expansive grout mixture allows the tunnel to be filled more easily and quickly, achieving the purpose of rapid interception.

[0050] The solid-liquid ratio of bentonite, glutinous rice paste and water is 2:1 to 3:1, and the mass ratio of bentonite and glutinous rice paste is 1:1 to 3:1.

[0051] S109, grouting boreholes are carried out in the coal mine roadway area exposed by the cutoff boreholes on the ground; the grouting boreholes stop drilling when they reach a height of 5 meters above the hydraulic fracturing range.

[0052] The number of boreholes in the grouting borehole group is the same as the number of boreholes in the cutoff borehole group.

[0053] S110, at a distance x above the roadway roof revealed by the cut-off borehole group, a combined borehole blasting is carried out until the rock mass within x range above the coal mine roadway detaches from the strata and reaches the roadway.

[0054] S111 involves implementing a grouting borehole group in the coal mine roadway area exposed by the ground-to-surface intercepting borehole group, drilling to the bottom plate of the roadway, and grouting; the grout is a mixture of bentonite, glutinous rice paste and water.

[0055] The grout injection volume is W = c × x × L × d. Where c is the safety factor, ranging from 1 to 1.5, and d is the roadway width, obtained through mining design.

[0056] S112, complete the sealing of the water inrush point.

[0057] This application utilizes borehole blasting to fracture and expand the rock mass in the tunnel roof (therefore, the blasting height is determined in conjunction with the fracture and expansion coefficient) to seal the coal mine roadway, achieving rapid sealing. Subsequently, grouting is injected into the fractured and expanded rock mass for reinforcement, and the required length L of the reinforced fractured and expanded body is calculated using the coal pillar method. This achieves both rapid closure and safety protection. Furthermore, to ensure the effectiveness of the fracture and expansion, hydraulic fracturing is performed beforehand, injecting a large amount of expansive grout to facilitate faster and more efficient filling of the roadway, thus achieving rapid closure.

[0058] In another exemplary embodiment of this application, a large mine water inrush occurred during the mining of the 5003 working face in a coal mine. To resume production as quickly as possible, it was necessary to intercept the water inrush point. The following method for rapid interception of water inrush points in coal mine roadways was adopted, with the specific steps as follows:

[0059] Step 1: Through observation during underground water inrush, the location of the water inrush point in the coal mine roadway was determined to be 253 meters from the cut-in point in the transport roadway.

[0060] Step 2: Determine the cut-off point of the coal mine roadway. The cut-off point is located 365 meters from the cut-off point in the transport roadway.

[0061] Step 3: Conduct damming exploration holes from the ground to the damming point and obtain rock cores from the tunnel roof.

[0062] Step 4: Determine the height of the roadway revealed by the interception exploration hole, h = 4 meters, and measure the water flow velocity, v = 720 m / h.

[0063] Step 5: Calculate the distribution length L of the cutoff borehole group. Where K is 5, K p The tensile strength of the mixture of crushed rock core from the tunnel roof and cement in a 1:1 ratio, with a cement water-cement ratio of 1:1 to 1:2 and containing 5% to 10% accelerator, K p The pressure was obtained experimentally as 0.2 MPa. p is the equivalent pressure. Where ρ is the density of water and v is 720 m / h. Therefore, L is taken as 20 meters.

[0064] Step Six: Implement the interception borehole group. The interception borehole group is constructed from the ground, with the final borehole located downstream of the water inrush point in the roadway, extending within 20 meters along the roadway from the interception point. The interception borehole group consists of a total of 8 interception boreholes.

[0065] Step 7: Perform hydraulic fracturing in the borehole at a distance x above the exposed roadway roof in the cutoff borehole group. x = (h / a) + 2 = 5.88 meters, where a = 1.03.

[0066] Step 8: Grout the fractures created by hydraulic fracturing. The injected grout is a mixture of bentonite, glutinous rice paste, and water, with a solid-liquid ratio of 2:1 and a mass ratio of bentonite to glutinous rice paste of 1:1.

[0067] Step Nine: Implement grouting boreholes in the coal mine roadway area exposed by the cutoff boreholes. Stop drilling when the grouting boreholes reach a height of 5 meters above the hydraulic fracturing zone.

[0068] Step 10: Conduct combined borehole blasting at a distance of 5.88 meters above the roadway roof revealed by the cutoff borehole group. Continue until the rock mass within 5.88 meters above the coal mine roadway detaches from the strata and reaches the roadway.

[0069] Step 11: Continue drilling the grouting borehole from Step 9, drill to the bottom of the tunnel, and grout 882 cubic meters.

[0070] Step 11: The water inrush point was sealed, thus achieving flood disaster relief.

[0071] The principles and implementation manners of the present application are described herein by using specific examples, and the above examples are only used to help understand the method of the present application and its core idea; meanwhile, for those skilled in the art, according to the idea of the present application, the specific implementation manners and application ranges will have changes. In conclusion, the content of the specification should not be understood as a limitation of the present application.

Claims

1. A method for rapid interception of water inrush points in coal mine roadways, characterized in that, The method for rapid interception of water inrush points in coal mine roadways includes: The location of the water inrush point can be determined by identifying the point where the water volume in the tunnel drainage ditch increases. Determine the interception point of the coal mine roadway based on the location of the water inrush point; Cut-off exploration holes are drilled from the ground to the cut-off point to obtain rock cores from the tunnel roof, and the fragmentation coefficient of the tunnel roof rock cores is determined based on the rock cores. Determine the height of the tunnel revealed by the interception exploration hole and obtain the water flow velocity; The distribution length of the cutoff borehole group is determined based on the tunnel height, the tensile strength of the material after the crushed rock core of the tunnel roof is mixed with cement, and the equivalent pressure determined by the water flow velocity. Starting from the interception point, the implementation range is defined by the distribution length of the interception borehole group, and the spacing between the interception boreholes is defined by a set distance. The interception borehole group is implemented along the direction of the roadway. Hydraulic fracturing was performed in the borehole at a distance x above the exposed roadway roof by the cut-off borehole group. Grouting is performed on the fractures created by hydraulic fracturing. Grouting boreholes are carried out in the coal mine roadway area exposed by the intercepting boreholes on the ground. At a distance x above the roadway roof revealed by the cut-off borehole group, a combined borehole blasting is carried out until the rock mass within x range above the coal mine roadway detaches from the strata and reaches the roadway. In the coal mine roadway area exposed by the surface interception borehole group, grouting borehole group is carried out to drill to the bottom plate of the roadway and grouting is performed. Complete the sealing of the water inrush point.

2. The method for rapid interception of water inrush points in coal mine roadways according to claim 1, characterized in that, The determination of the distribution length of the cutoff borehole group, based on the equivalent pressure determined by the roadway height, the tensile strength of the material after mixing the crushed rock core from the roadway roof with cement, and the water flow velocity, specifically includes: Using formula Determine the distribution length L of the cutoff borehole group; Where K is the safety factor, h is the tunnel height, and K p ρ represents the tensile strength of the material obtained by mixing the crushed rock core from the tunnel roof with cement, and p represents the equivalent compressive strength. ρ is the density of water, and v is the velocity of the water flow.

3. The method for rapid interception of water inrush points in coal mine roadways according to claim 2, characterized in that, The distance x above the roadway roof exposed by the cutoff borehole group is determined using the formula x = (h / a) + 2; where a is the fragmentation coefficient of the rock core from the roadway roof.

4. The method for rapid interception of water inrush points in coal mine roadways according to claim 1, characterized in that, The pressure in hydraulic fracturing is greater than the confining pressure.

5. The method for rapid interception of water inrush points in coal mine roadways according to claim 1, characterized in that, The injected slurry is a mixture of bentonite, glutinous rice paste and water.

6. The method for rapid interception of water inrush points in coal mine roadways according to claim 5, characterized in that, The solid-liquid ratio of bentonite, glutinous rice paste and water is 2:1 to 3:1, and the mass ratio of bentonite and glutinous rice paste is 1:1 to 3:

1.

7. The method for rapid interception of water inrush points in coal mine roadways according to claim 1, characterized in that, The number of boreholes in the grouting borehole group is the same as the number of boreholes in the cutoff borehole group.

8. The method for rapid interception of water inrush points in coal mine roadways according to claim 1, characterized in that, The aforementioned implementation of grouting boreholes in the coal mine roadway area exposed by the ground-facing intercepting borehole group, drilling to the roadway floor and grouting there, specifically includes: The injection volume W is determined using the formula W = c × x × L × d; Where c is the safety factor, x is the distance x above the roadway roof exposed by the cutoff borehole group, d is the roadway width, and L is the distribution length of the cutoff borehole group.

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