Self-pressure-bearing sleeve drilling pressure relief method for high-stress area of deep coal body

Abstract

The invention discloses a self-pressure-bearing sleeve drilling pressure relief method for a high-stress area of a deep coal body. The method comprises the steps that 1, rock mass mechanical parameters of all rock stratums of a stope are obtained; 2, constructing an initial ground stress balance model; 3, dividing different areas in front of the working face into a strong pressure relief area, a middle pressure relief area and a weak pressure relief area; 4, basic parameters of the self-pressure-bearing sleeve are determined; 5, determining the number of self-pressure-bearing sleeve drill holes, the length of the self-pressure-bearing sleeve drill holes and the arrangement distance of the self-pressure-bearing sleeve drill holes; 6, a self-pressure-bearing sleeve is installed on the roadway side, and pressure relief of a deep media high-stress area of the roadway side is conducted; and 7, calculating the pressure relief interval time, and drilling and unloading the deep coal body in the self-pressure-bearing sleeve for multiple times until the working face is stoped until the distance from the working face to the self-pressure-bearing sleeve meets a set threshold value. Through scientific numerical simulation and theoretical analysis, the optimal pressure relief range and parameters are determined, multi-time drilling pressure relief is achieved, stress concentration can be effectively reduced, and meanwhile the supporting strength and anti-disturbance capacity of roadway surrounding rock can be improved.

Description

Technical Field

[0001] The invention relates to a self-supporting sleeve drilling pressure relief method in a high stress zone of a deep coal body. Background Art

[0002] During coal mining, high stress concentration in the deep surrounding rock of the tunnel is one of the main causes of impact mine pressure disasters. When the static load and dynamic load on the coal body exceed its ultimate strength, the coal body will be damaged, and the elastic energy stored in the coal body and the roof and floor will be released rapidly, resulting in serious deformation of the tunnel, damage to the support structure, and even casualties and equipment damage. Therefore, how to effectively reduce the high stress in the deep surrounding rock of the tunnel and ensure safe and efficient production of coal mines has become a technical problem that needs to be solved in the process of coal mining.

[0003] The drilling pressure relief method has been widely used in the prevention and control of rock burst due to its simple operation, low construction cost, and strong applicability to geological conditions. It can effectively reduce the static load on the coal body by drilling pressure relief on the coal body. However, there are many problems in the practical application of traditional drilling pressure relief technology:

[0004] First, single pressure relief is insufficient: when a single drilling pressure relief is implemented in the tunnel surrounding rock, the pressure relief is often insufficient, and the deep part of the tunnel surrounding rock still maintains a high stress state, posing the risk of impact mine pressure.

[0005] Second, multiple pressure relief damage: When multiple drilling pressure relief is carried out on the tunnel surrounding rock, the integrity of the tunnel shallow surrounding rock is seriously damaged, which reduces the stability of the tunnel. When dynamic load acts on the tunnel surrounding rock, it is easy to cause impact in the tunnel, increasing the risk of accidents.

[0006] Therefore, there is an urgent need for a new pressure relief method that can effectively reduce high stress while maintaining the structural integrity and stability of the tunnel surrounding rock and enhancing its anti-disturbance ability. Summary of the invention

[0007] In view of the above problems, the present invention provides a self-supporting sleeve drilling pressure relief method for high stress areas in deep coal bodies. Through scientific numerical simulation and theoretical analysis, the optimal pressure relief range and parameters are determined, and multiple drilling pressure relief is achieved. It can effectively reduce stress concentration while improving the support strength and anti-disturbance ability of the tunnel surrounding rock.

[0008] In order to achieve the above technical objectives and the above technical effects, the present invention is implemented through the following technical solutions:

[0009] A method for relieving pressure by drilling a self-supporting sleeve in a high stress zone of a deep coal body, comprising the following steps:

[0010] Step 1, obtaining the rock mass mechanical parameters of each rock layer in the mining area;

[0011] Step 2: constructing a model of initial ground stress balance according to the stratigraphic structural conditions of the coal seam strike;

[0012] Step 3: According to the numerical simulation results, the distribution characteristics of the advance support pressure of the working face are obtained, and along the advancing direction of the working face, different areas in front of the working face are divided into high, medium and low stress areas, which correspond to strong pressure relief areas, medium pressure relief areas and weak pressure relief areas respectively;

[0013] Step 4: Calculate the lateral bearing pressure distribution characteristics of the tunnel according to the determined working face advance bearing pressure distribution characteristics, and determine the basic parameters of the self-bearing sleeve so that the critical pressure of the self-bearing sleeve meets the bearing capacity;

[0014] Step 5: Determine the number of self-contained sleeve holes, the length of the self-contained sleeve holes, and the spacing of the self-contained sleeve holes according to the advanced stress concentration level of the working face and the strength of the self-contained sleeve holes;

[0015] Step 6: According to the self-contained sleeve drilling arrangement plan obtained in step 5, the self-contained sleeve is installed on the sidewall and the pressure is relieved in the high stress area of ​​the media deep in the sidewall;

[0016] Step 7: Calculate the pressure relief interval according to the stress concentration coefficient corresponding to the drilling position in front of the working face, and perform multiple drilling and unloading of the deep coal body in the self-contained sleeve until the working face is mined to a distance from the self-contained sleeve that meets the set threshold. .

[0017] Preferably, step 1 specifically comprises the following steps:

[0018] Step 1.1, obtain rock samples from each rock layer in the stope, measure the elastic modulus of the rock samples, and obtain the volume model and shear modulus mechanical parameters of the rock mass after calculation;

[0019] Step 1.2, establish a numerical model of rock samples with the same size, and perform initial parameter assignment on the mechanical parameters of the blocks and joints in the rock samples;

[0020] Step 1.3, adjust the mechanical parameters of the blocks and joints until the elastic modulus of the rock sample in the rock sample numerical model is consistent with the actual rock sample result, and use the data at this time as the rock mass mechanical parameters in the rock sample numerical model.

[0021] Preferably, step 2 specifically comprises the following steps:

[0022] Step 2.1, construct a model of the working face advancement direction scale, with the left and right sides of the model fixed in the horizontal direction and the bottom of the model fixed in the vertical direction. The lateral pressure coefficient of the model is determined according to the measured ground stress environment of the coal mine, and a uniformly distributed load is applied to the top of the model to replace the static load of the overlying rock layer;

[0023] Step 2.2, group the rock layers in the model according to the actual geological column chart of the mine;

[0024] Step 2.3: Apply gravity acceleration to the model, assign the mechanical parameters of the blocks and joints obtained in step 1.3 to the corresponding rock layers, and obtain a model of initial ground stress equilibrium.

[0025] Preferably, step 3 specifically comprises the following steps:

[0026] Step 3.1, excavate the coal seam in the initial geostress balance model to the actual advancement position on site, solve the initial geostress balance model to obtain the distribution characteristics of the advanced support pressure of the working face, and find the value and position corresponding to the maximum vertical stress;

[0027] Step 3.2: According to the calculation results, the different areas in front of the working face are divided into high, medium and low stress areas, corresponding to the strong pressure relief area, medium pressure relief area and weak pressure relief area respectively, where:

[0028] The range of strong pressure relief area is: σx>σoriginal+2(σ max -σ original) / 3;

[0029] The range of the middle pressure relief area is: σ original + 2 (σ max -σoriginal) / 3<σx<σoriginal+(σ max -σ original) / 3;

[0030] The range of weak pressure relief area is: σ original + 2 (σ max -σoriginal) / 3>σx>σoriginal;

[0031] Where: σx is the stress state at a distance of x meters from the working face; σoriginal is the stress state of the original rock of the coal seam; σ max is the peak value of the advance support pressure.

[0032] Preferably, step 4 specifically comprises the following steps:

[0033] Step 4.1: Determine the peak value of the lateral bearing pressure. The calculation method is: 侧max = k·γ·H;

[0034] Step 4.2: Determine the basic parameters of the self-contained sleeve and calculate the critical pressure of the self-contained sleeve:

[0035]

[0036] Step 4.3: Determine whether the self-contained sleeve meets the load-bearing capacity: P 自承 >σ max +σ 侧max , when the self-supporting sleeve meets the bearing capacity, proceed to the next step;

[0037] In the formula, σ侧max is the peak value of lateral support pressure, k is the lateral pressure coefficient, γ is the average bulk density of rock mass, and H is the buried depth of coal seam; P 自承 is the critical pressure of the self-contained sleeve, E 套 is the elastic modulus of the self-supporting sleeve, υ 套 is the Poisson's ratio of the self-supporting sleeve, t is the thickness of the self-supporting sleeve, D 套外 It is the outer diameter of the self-supporting sleeve.

[0038] Preferably, step 5 specifically comprises the following steps:

[0039] Step 5.1: Calculate the peak position Z of the lateral support pressure P :

[0040]

[0041] Step 5.2: Determine the range of pressure relief drilling:

[0042]

[0043] Step 5.3, determine the number of pressure relief holes n:

[0044]

[0045] Step 5.4: Determine the length L of the self-supporting sleeve 钻 :

[0046] L 钻 =0.8Z P

[0047] Step 5.5: Determine the pressure relief drilling spacing h 间 :

[0048]

[0049] Step 5.6: Determine the spacing l between self-supporting sleeves 间排距 :

[0050]

[0051] Among them, when σx>σoriginal+2(σ max -σoriginal) / 3, take σx=σ max ;

[0052] When σoriginal+2(σ max -σoriginal) / 3<σx<σoriginal+(σ max -σ original) / 3, take σx=σ original+2(σ max -σ original) / 3;

[0053] When σoriginal+2(σ max-σ original) / 3>σx>σ original, take σx=σ original+(σ max -σ original) / 3;

[0054] Where: r is the approximate radius of the tunnel, γ is the average bulk density of the rock mass; H 埋 is the buried depth of the tunnel; c is the cohesion of the coal seam interface; is the internal friction angle of the coal seam interface; H 煤 is the thickness of the coal seam; F 钻 is the range corresponding to the pressure relief; R 钻 is the diameter of a single drill hole.

[0055] Preferably, step 6 specifically comprises the following steps:

[0056] Step 6.1: Drilling hole with self-pressure sleeve: Drilling diameter = D 套外

[0057] Step 6.2: Drilling into the self-contained sleeve: The outer diameter of the sleeve is D 套外 , inner diameter D 套内 , sleeve length penetrates into the coal wall L 钻 , strengthen the support of the plastic zone of the tunnel surrounding rock;

[0058] Step 6.3: Insert the drill rod to relieve pressure: the diameter of the drill rod is smaller than the inner diameter of the sleeve, and the drilling length is 2Z P , passing through the high stress peak area, and realizing the pressure relief of the high stress area of ​​the deep media in the tunnel wall.

[0059] Preferably, step 7 specifically includes the following steps:

[0060] Step 7.1. Calculate the pressure relief interval time T according to the stress concentration factor corresponding to the drilling position in front of the working face. 间 Repeatedly unload the high stress area of ​​the coal body until the working face is mined to a distance from the self-pressure sleeve that meets the set threshold

[0061] The pressure relief interval time calculation method is:

[0062] Step 7.2, remove the self-pressure sleeve from the tunnel wall.

[0063] Preferably, in step 1, UDEC discrete element software is used to obtain the rock mass mechanical parameters of each rock layer in the stope, and the threshold is set in step 7. is 2m.

[0064] The beneficial effects of the present invention are:

[0065] 1. The present invention uses UDEC discrete element software to restore the real ground stress environment conditions of the rock formation. The simulation process is consistent with the actual situation on site. The stress distribution characteristics along the advancing direction of the working face are obtained through numerical simulation, and the pressure relief area is divided accordingly, which provides a scientific basis for the reasonable design of self-pressure sleeve drilling pressure relief. The present invention can accurately estimate the pressure relief effect under the actual conditions of the high stress area in the deep part of the coal mine recovery roadway, and improve the reliability and scientificity of the design.

[0066] 2. The present invention calculates the plastic zone range and lateral support pressure of the tunnel surrounding rock through theoretical analysis, and determines the parameters such as the length of the self-supporting sleeve, the thickness of the cylinder wall, the spacing of the borehole pressure relief, the pressure relief depth and the number of pressure relief. Through accurate parameter determination, the high efficiency and safety of the pressure relief process are ensured, and the structural integrity of the tunnel surrounding rock can be maintained during multiple borehole pressure relief processes, thereby improving its support strength and anti-disturbance capability.

[0067] 3. The present invention effectively reduces the stress concentration coefficient in the deep part of the tunnel surrounding rock through multiple drilling pressure relief, releases high stress, and ensures that the surrounding rock remains at a low stress level. At the same time, the stress concentration of the advanced working face is monitored in real time, and the pressure relief scheme is dynamically adjusted according to the monitoring results to ensure the continuity and reliability of the pressure relief effect, reduce the probability and intensity of impact mine pressure dynamic disasters, and ensure safe and efficient production of coal mines.

[0068] 4. The present invention provides a new technical solution for multiple pressure relief and support strengthening in high stress areas of coal bodies, and can carry out numerical calculations for pressure relief effect evaluation under different geological structures and ground stress conditions, which has important theoretical and application value for studying pressure relief methods in high stress areas of coal bodies. The method of the present invention provides a scientific reference and effective means for solving the problem of pressure relief in deep high stress areas of coal mine recovery tunnels, and has broad engineering application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] Figure 1 It is a flow chart of a self-supporting sleeve drilling pressure relief method for a high stress zone of a deep coal body according to the present invention;

[0070] Figure 2 A schematic diagram of numerical simulation rock mechanics parameter calibration according to an embodiment of the present invention;

[0071] Figure 3 A schematic diagram of a numerical model for determining the advance support pressure of a working face according to an embodiment of the present invention;

[0072] Figure 4 A schematic diagram of the distribution characteristics of the advanced support pressure of the working surface according to an embodiment of the present invention;

[0073] Figure 5 A schematic diagram of the division of the degree of leading stress concentration on the working surface according to an embodiment of the present invention;

[0074] Figure 6 This is a distribution diagram of the leading support pressure and the lateral support pressure of the working face according to an embodiment of the present invention;

[0075] Figure 7 A schematic diagram of a self-supporting sleeve according to an embodiment of the present invention;

[0076] Figure 8 A schematic plan view of the construction layout of a self-supporting sleeve according to an embodiment of the present invention;

[0077] Fig. 9 A three-dimensional schematic diagram of the actual construction layout of a self-supporting sleeve according to an embodiment of the present invention;

[0078] Fig.10 It is a schematic diagram of a method for determining the pressure relief range and sleeve length of a self-pressure sleeve according to an embodiment of the present invention. DETAILED DESCRIPTION

[0079] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0080] like Figure 1 As shown, a method for relieving pressure by drilling a hole with a self-supporting sleeve in a high stress zone of a deep coal body comprises the following steps:

[0081] Step 1: Obtain rock mass mechanical parameters of each rock layer in the stope. In this embodiment, the preferred step 1 specifically includes the following steps:

[0082] Step 1.1: Obtain rock samples from each rock layer in the mining area. The elastic modulus of the rock samples can be measured by a press, and the mechanical parameters such as the volume model and shear modulus of the rock mass can be obtained after calculation using the RQD method (rock quality designation).

[0083] Step 1.2: Establish a numerical model of the rock sample in the numerical model of the UDEC discrete element software with equal dimensions, such as Figure 2 As shown, the mechanical parameters of the blocks and joints in the rock sample are initially assigned, where the joint model is set to a surface contact model, the block model is set to a Mohr-Coulomb model, the joint mechanical parameters include shear stiffness, normal stiffness, cohesion, friction angle, and tensile strength, and the block mechanical parameters include elastic modulus, Poisson's ratio, and density.

[0084] Step 1.3, continuously adjust the mechanical parameters of the block and joints until the elastic modulus of the rock sample in the rock sample numerical model is consistent with the actual rock sample result, and use the data at this time as the rock mass mechanical parameters in the UDEC rock sample numerical model. The specific mechanical parameters obtained in this embodiment are shown in Table 1 below:

[0085] Table 1 Rock mechanics parameters in discrete element numerical analysis

[0086]

[0087] Step 2: construct an initial ground stress balance model according to the coal seam strike and stratum structural conditions. In this embodiment, Figure 3 As shown, the preferred step 2 specifically includes the following steps:

[0088] Step 2.1, construct a model of the working face advancement direction scale, with the left and right sides of the model fixed in the horizontal direction and the bottom of the model fixed in the vertical direction. The lateral pressure coefficient of the model is determined according to the measured ground stress environment of the coal mine, and a uniformly distributed load is applied to the top of the model to replace the static load of the overlying rock layer;

[0089] Step 2.2: According to the actual geological columnar diagram of the mine, the rock layers in the model are grouped, wherein the contact model of the joints in the coal seam and the rock layer is a surface contact model.

[0090] Step 2.3: Apply gravity acceleration to the model, assign the mechanical parameters of the blocks and joints obtained in step 1.3 to the corresponding rock layers, and obtain a model of initial ground stress equilibrium.

[0091] Step 3: According to the numerical simulation results, the distribution characteristics of the advance support pressure of the working face are obtained, and along the advancing direction of the working face, different areas in front of the working face are divided into high, medium and low stress areas, which correspond to the strong pressure relief area, the medium pressure relief area and the weak pressure relief area, respectively. In this embodiment, preferably, step 3 specifically includes the following steps:

[0092] Step 3.1: Excavate the coal seam in the initial geostress balance model to the actual advancement position on site, solve the initial geostress balance model, obtain the distribution characteristics of the advanced support pressure of the working face, and find the value and position corresponding to the maximum vertical stress, such as Figure 4 shown.

[0093] Step 3.2: According to the calculation results, the different areas in front of the working face are divided into high, medium and low stress areas, which correspond to strong pressure relief area, medium pressure relief area and weak pressure relief area respectively. The specific division method is as follows:

[0094] The range of strong pressure relief area is: σx>σoriginal+2(σ max -σ original) / 3;

[0095] The range of the middle pressure relief area is: σ original + 2 (σ max -σoriginal) / 3<σx<σoriginal+(σ max -σ original) / 3;

[0096] The range of weak pressure relief area is: σ original + 2 (σ max-σoriginal) / 3>σx>σoriginal;

[0097] Where: σx is the stress state at a distance of x meters from the working face; σoriginal is the stress state of the original rock of the coal seam; σ max is the peak value of the advance support pressure.

[0098] In this embodiment, Figure 5 As shown, it is calculated that 13-14m and 37-91m in front of the working face are weak pressure relief areas, 14-16m and 27-37m in front of the working face are medium pressure relief areas, and 16-27m in front of the working face is strong pressure relief area.

[0099] Step 4: Calculate the lateral bearing pressure distribution characteristics of the tunnel according to the determined working face advance bearing pressure distribution characteristics, and determine the basic parameters of the self-supporting sleeve so that the critical pressure of the self-supporting sleeve meets the bearing capacity. Figure 6 and Figure 7 As shown, step 4 specifically includes the following steps:

[0100] Step 4.1: Determine the peak value of the lateral bearing pressure. The calculation method is: 侧max = k·γ·H;

[0101] In the formula, σ 侧max is the peak value of lateral bearing pressure, k is the lateral pressure coefficient, γ is the average bulk density of rock mass, and H is the depth of coal seam. In this embodiment, according to the field measured data, k is taken as 1.5, γ is taken as 25000Kg / m3, H is taken as 500m, and σ is calculated. 侧max It is 18.75MPa.

[0102] Step 4.2, determine the basic parameters of the self-contained sleeve, including the outer diameter of the self-contained sleeve, the thickness of the self-contained sleeve, the yield strength of the self-contained sleeve, the elastic modulus of the self-contained sleeve, etc., and calculate the critical pressure of the self-contained sleeve:

[0103]

[0104] Where P 自承 is the critical pressure of the self-contained sleeve (in KPa), E 套 is the elastic modulus of the self-supporting sleeve (in KPa), υ 套 is the Poisson's ratio of the self-contained sleeve, t is the thickness of the self-contained sleeve (in mm), D 套外 It is the outer diameter of the self-supporting sleeve (in mm).

[0105] In this embodiment, the elastic modulus of the self-pressure sleeve is 2e 5 Kpa, Poisson's ratio is 0.15, t is 160mm, the outer diameter of the self-pressure sleeve is 200mm, and the critical pressure of the self-pressure sleeve is calculated to be 3.27Gpa.

[0106] Step 4.3: Determine whether the self-contained sleeve meets the load-bearing capacity: P 自承 >σ max +σ 侧max , when the self-supporting sleeve meets the bearing capacity, proceed to the next step.

[0107] In this embodiment, it is calculated that 3270MPa>18.75MPa+26Mpa, which meets the bearing capacity.

[0108] Step 5: Determine the number of self-contained sleeve holes, the length of the self-contained sleeve holes, and the spacing of the self-contained sleeve holes according to the advanced stress concentration level of the working surface and the strength of the self-contained sleeve. Figure 8 As shown, preferably, step 5 specifically includes the following steps:

[0109] Step 5.1: Calculate the peak position Z of the lateral support pressure P :

[0110]

[0111] Where: r is the approximate radius of the tunnel, γ is the average bulk density of the rock mass; H 埋 is the buried depth of the tunnel; c is the cohesion of the coal seam interface; is the internal friction angle of the coal seam interface. In this embodiment, the approximate radius of the tunnel r is 2m, γ is 25000Kg / m3, H 埋 is 500m, c is 1.2MPa, is 30°, and Z is calculated P It is 10.2.

[0112] Step 5.2: Determine the range of pressure relief drilling:

[0113]

[0114] Where: H 煤 is the thickness of the coal seam; F 钻 is the range corresponding to the pressure relief. In this embodiment, the coal seam thickness H 煤 Take 6m, σx as 24MPa, σoriginal as 21Mpa, and the calculated drilling range is 0.86m.

[0115] Step 5.3, determine the number of pressure relief holes n:

[0116]

[0117] Where: R 钻 is the diameter of a single borehole. In this embodiment, R 钻 is 200mm, and n=4.3 is calculated, so the number of holes n is 4.

[0118] Step 5.4: Determine the length L of the self-supporting sleeve 钻 :

[0119] L 钻 =0.8Z P

[0120] Step 5.5: Determine the pressure relief drilling spacing h 间 :

[0121]

[0122] In this embodiment, the coal seam thickness is 6 m, the number of drill holes is 4, and the drill hole spacing is 1.5 m.

[0123] Step 5.6: Determine the spacing l between self-supporting sleeves 间排距 :

[0124]

[0125] Among them, when σx>σoriginal+2(σ max -σoriginal) / 3, take σx=σ max ;

[0126] When σoriginal+2(σ max -σoriginal) / 3<σx<σoriginal+(σ max -σ original) / 3, take σ=σ original+2(σ max -σ original) / 3;

[0127] When σoriginal+2(σ max -σ original) / 3>σ>σ original, take σx=σ original+(σ max -σoriginal) / 3.

[0128] In this embodiment, σ is taken as 21 MPa. When σx is 24 MPa, the spacing between drill holes is 0.875 m.

[0129] Step 6: According to the self-contained sleeve drilling arrangement plan obtained in step 5, the self-contained sleeve is installed on the sidewall and the pressure is relieved in the high stress area of ​​the media deep in the sidewall. Fig. 9 and Fig.10 As shown, step 6 specifically includes the following steps:

[0130] Step 6.1: Drilling hole with self-pressure sleeve: Drilling diameter = D 套外 In this embodiment, the diameter of the drill hole is 200 mm.

[0131] Step 6.2: Drilling into the self-contained sleeve: The outer diameter of the sleeve is D 套外 (Unit: mm), inner diameter D 套内(Unit: mm), divided into multiple sections, each section is 1m long, assembled by thread, the sleeve length penetrates into the coal wall L 钻 , strengthen the support of the plastic zone of the tunnel surrounding rock.

[0132] Step 6.3: Insert the drill rod to relieve pressure: the diameter of the drill rod is smaller than the inner diameter of the sleeve, and the drilling length is 2Z P , passing through the high stress peak area, and realizing the pressure relief of the high stress area of ​​the deep media in the tunnel wall. In this embodiment, the drill pipe diameter is taken as (D 套外 -50mm), Z P The calculated value is 10.2, so the borehole pressure relief depth should be 20.4m.

[0133] Step 7: Calculate the pressure relief interval according to the stress concentration coefficient corresponding to the drilling position in front of the working face, and perform multiple drilling and unloading of the deep coal body in the self-contained sleeve until the working face is mined to a distance from the self-contained sleeve that meets the set threshold. .

[0134] Preferably, step 7 specifically includes the following steps:

[0135] Step 7.1. Calculate the pressure relief interval time T according to the stress concentration factor corresponding to the drilling position in front of the working face. 间 Repeatedly unload the high stress area of ​​the coal body until the working face is mined to a distance from the self-pressure sleeve that meets the set threshold For example, setting a threshold is 2m.

[0136] The pressure relief interval time calculation method is:

[0137] In this embodiment, σoriginal is taken as 21 MPa, σx is taken as 24 MPa, and the drilling pressure relief interval is 0.875 days.

[0138] Step 7.2, remove the self-pressure sleeve from the tunnel wall.

[0139] 1. The present invention uses UDEC discrete element software to restore the real ground stress environment conditions of the rock formation. The simulation process is consistent with the actual situation on site. The stress distribution characteristics along the advancing direction of the working face are obtained through numerical simulation, and the pressure relief area is divided accordingly, which provides a scientific basis for the reasonable design of self-pressure sleeve drilling pressure relief. The present invention can accurately estimate the pressure relief effect under the actual conditions of the high stress area in the deep part of the coal mine recovery roadway, and improve the reliability and scientificity of the design.

[0140] 2. The present invention calculates the plastic zone range and lateral support pressure of the tunnel surrounding rock through theoretical analysis, and determines the parameters such as the length of the self-supporting sleeve, the thickness of the cylinder wall, the spacing of the borehole pressure relief, the pressure relief depth and the number of pressure relief. Through accurate parameter determination, the high efficiency and safety of the pressure relief process are ensured, and the structural integrity of the tunnel surrounding rock can be maintained during multiple borehole pressure relief processes, thereby improving its support strength and anti-disturbance capability.

[0141] 3. The present invention effectively reduces the stress concentration coefficient in the deep part of the tunnel surrounding rock through multiple drilling pressure relief, releases high stress, and ensures that the surrounding rock remains at a low stress level. At the same time, the stress concentration of the advanced working face is monitored in real time, and the pressure relief scheme is dynamically adjusted according to the monitoring results to ensure the continuity and reliability of the pressure relief effect, reduce the probability and intensity of impact mine pressure dynamic disasters, and ensure safe and efficient production of coal mines.

[0142] 4. The present invention provides a new technical solution for multiple pressure relief and support strengthening in high stress areas of coal bodies, and can carry out numerical calculations for pressure relief effect evaluation under different geological structures and ground stress conditions, which has important theoretical and application value for studying pressure relief methods in high stress areas of coal bodies. The method of the present invention provides a scientific reference and effective means for solving the problem of pressure relief in deep high stress areas of coal mine recovery tunnels, and has broad engineering application prospects.

[0143] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A self-supporting sleeve drilling pressure relief method for high stress areas of deep coal bodies, characterized in that: The following steps are involved: Step 1, obtaining the rock mass mechanical parameters of each rock layer in the mining area; Step 2: constructing a model of initial ground stress balance according to the stratigraphic structural conditions of the coal seam strike; Step 3: According to the numerical simulation results, the distribution characteristics of the advance support pressure of the working face are obtained, and along the advancing direction of the working face, different areas in front of the working face are divided into high, medium and low stress areas, which correspond to strong pressure relief areas, medium pressure relief areas and weak pressure relief areas respectively; Step 4: Calculate the lateral bearing pressure distribution characteristics of the tunnel according to the determined working face advance bearing pressure distribution characteristics, and determine the basic parameters of the self-bearing sleeve so that the critical pressure of the self-bearing sleeve meets the bearing capacity; Step 5: Determine the number of self-contained sleeve holes, the length of the self-contained sleeve holes, and the spacing of the self-contained sleeve holes according to the advanced stress concentration level of the working face and the strength of the self-contained sleeve holes; Step 6: According to the self-contained sleeve drilling arrangement plan obtained in step 5, the self-contained sleeve is installed on the sidewall and the pressure is relieved in the high stress area of ​​the media deep in the sidewall; Step 7: Calculate the pressure relief interval according to the stress concentration coefficient corresponding to the drilling position in front of the working face, and perform multiple drilling and unloading of the deep coal body in the self-contained sleeve until the working face is mined to a distance from the self-contained sleeve that meets the set threshold.

2. A self-supporting sleeve drilling pressure relief method for high stress areas of deep coal bodies according to claim 1, characterized in that: Step 1 specifically includes the following steps: Step 1.1, obtain rock samples from each rock layer in the stope, measure the elastic modulus of the rock samples, and obtain the volume model and shear modulus mechanical parameters of the rock mass after calculation; Step 1.2, establish a numerical model of rock samples with the same size, and perform initial parameter assignment on the mechanical parameters of the blocks and joints in the rock samples; Step 1.3, adjust the mechanical parameters of the blocks and joints until the elastic modulus of the rock sample in the rock sample numerical model is consistent with the actual rock sample result, and use the data at this time as the rock mass mechanical parameters in the rock sample numerical model.

3. A self-supporting sleeve drilling pressure relief method for high stress areas of deep coal bodies according to claim 2, characterized in that: Step 2 specifically includes the following steps: Step 2.1, construct a model of the working face advancement direction scale, with the left and right sides of the model fixed in the horizontal direction and the bottom of the model fixed in the vertical direction. The lateral pressure coefficient of the model is determined according to the measured ground stress environment of the coal mine, and a uniformly distributed load is applied to the top of the model to replace the static load of the overlying rock layer; Step 2.2, group the rock layers in the model according to the actual geological column chart of the mine; Step 2.3: Apply gravity acceleration to the model, assign the mechanical parameters of the blocks and joints obtained in step 1.3 to the corresponding rock layers, and obtain a model of initial ground stress equilibrium.

4. A self-supporting sleeve drilling pressure relief method for high stress areas of deep coal bodies according to claim 3, characterized in that: Step 3 specifically includes the following steps: Step 3.1, excavate the coal seam in the initial geostress balance model to the actual advancement position on site, solve the initial geostress balance model to obtain the distribution characteristics of the advanced support pressure of the working face, and find the value and position corresponding to the maximum vertical stress; Step 3.2: According to the calculation results, the different areas in front of the working face are divided into high, medium and low stress areas, which correspond to strong pressure relief area, medium pressure relief area and weak pressure relief area respectively, where: The range of strong pressure relief area is: σx>σoriginal+2(σ max -σ original) / 3; The range of the middle pressure relief area is: σ original + 2 (σ max -σoriginal) / 3<σx<σoriginal+(σ max -σ original) / 3; The range of weak pressure relief area is: σ original + 2 (σ max -σoriginal) / 3>σx>σoriginal; Where: σx is the stress state at a distance of x meters from the working face; σoriginal is the stress state of the original rock of the coal seam; σ max is the peak value of the advance support pressure.

5. A self-supporting sleeve drilling pressure relief method for high stress areas of deep coal bodies according to claim 4, characterized in that: Step 4 specifically includes the following steps: Step 4.1: Determine the peak value of the lateral bearing pressure. The calculation method is: 侧max = k·γ·H; Step 4.2: Determine the basic parameters of the self-contained sleeve and calculate the critical pressure of the self-contained sleeve: Step 4.3: Determine whether the self-contained sleeve meets the load-bearing capacity: P 自承 >σ max +σ 侧max , when the self-supporting sleeve meets the bearing capacity, proceed to the next step; In the formula, σ 侧max is the peak value of lateral support pressure, k is the lateral pressure coefficient, γ is the average bulk density of rock mass, and H is the buried depth of coal seam; P 自承 is the critical pressure of the self-contained sleeve, E 套 is the elastic modulus of the self-supporting sleeve, υ 套 is the Poisson's ratio of the self-supporting sleeve, t is the thickness of the self-supporting sleeve, D 套外 It is the outer diameter of the self-supporting sleeve.

6. A self-supporting sleeve drilling pressure relief method for high stress areas in deep coal bodies according to claim 5, characterized in that: Step 5 specifically includes the following steps: Step 5.1: Calculate the peak position Z of the lateral support pressure P : Step 5.2: Determine the range of pressure relief drilling: Step 5.3, determine the number of pressure relief holes n: Step 5.4: Determine the length L of the self-supporting sleeve 钻 : L 钻 =0.8Z P Step 5.5: Determine the pressure relief drilling spacing h 间 : Step 5.6: Determine the spacing l between self-supporting sleeves 间排距 : Where, when σx>σoriginal+2(σ max -σoriginal) / 3, take σx=σ max ; When σoriginal + 2(σ max - σoriginal) / 3 < σx < σoriginal + (σ max - σoriginal) / 3, take σx = σoriginal + 2(σ max - σoriginal) / 3; When +2(s max -σoriginal) / 3>σx>σoriginal, then σx=σoriginal+(σ max -s) / 3; Where: r is the approximate radius of the tunnel, γ is the average bulk density of the rock mass; H 埋 is the buried depth of the tunnel; c is the cohesion of the coal seam interface; is the internal friction angle of the coal seam interface; H 煤 is the thickness of the coal seam; F 钻 is the range corresponding to the pressure relief; R 钻 is the diameter of a single drill hole.

7. A self-supporting sleeve drilling pressure relief method for high stress areas in deep coal bodies according to claim 6, characterized in that: Step 6 specifically includes the following steps: Step 6.1: Drilling hole with self-pressure sleeve: Drilling diameter = D 套外 Step 6.2: Drilling into the self-contained sleeve: The outer diameter of the sleeve is D 套外 , inner diameter D 套内 , sleeve length penetrates into the coal wall L 钻 , strengthen the support of the plastic zone of the tunnel surrounding rock; Step 6.3: Insert the drill rod to relieve pressure: the diameter of the drill rod is smaller than the inner diameter of the sleeve, and the drilling length is 2Z P , passing through the high stress peak area, and realizing the pressure relief of the high stress area of ​​the deep media in the tunnel wall.

8. A method for relieving pressure by drilling a self-supporting sleeve in a high stress zone of a deep coal body according to claim 7, characterized in that: Step 7 specifically includes the following steps: Step 7.

1. Calculate the pressure relief interval time T according to the stress concentration factor corresponding to the drilling position in front of the working face. 间 Repeatedly unload the high stress area of ​​the coal body until the working face is mined to a distance from the self-pressure sleeve that meets the set threshold The pressure relief interval time calculation method is: Step 7.2, remove the self-pressure sleeve from the tunnel wall.

9. A method for relieving pressure by drilling a self-supporting sleeve in a high stress zone of a deep coal body according to claim 8, characterized in that: In step 1, UDEC discrete element software is used to obtain the rock mass mechanical parameters of each rock layer in the stope, and the threshold is set in step 7. is 2m.

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