A precise calculation method for the impact resistance of coal mine tunnels

Abstract

A precise calculation method for the impact resistance of coal mine tunnels. By conducting dynamic load impact tests on materials taken from various support components on site, the details such as material collection, experimental equipment, and loading methods in the experiment are clarified, and the true impact resistance energy value can be obtained. According to the stability of the surrounding rock, the energy that can be absorbed by the support components and pressure relief holes of the roof and the side is weighted. The basic data source is real and effective, and the energy calculation method is scientific and reasonable. A specific calculation formula for the energy absorbed by the pressure relief hole is proposed, and the impact resistance energy of the pressure relief measures is comprehensively weighted calculated according to the surrounding rock conditions, and the influence of the pressure relief measures on the impact resistance of the tunnel is fully considered. The impact resistance of various support structures including anchor rods, anchor cables, trays, steel belts, and surface protection nets in the roof and side is fully considered, and the energy that can be absorbed by the advanced support measures is fully considered, so that the calculation results are more in line with the actual situation on site.

Description

Technical Field

[0001] The invention relates to a method for accurately calculating the impact resistance of a coal mine tunnel. Background Art

[0002] In recent years, coal mine tunnel impact accidents have occurred frequently, causing extremely heavy casualties and property losses. Reasonable support and pressure relief measures are the prevention and control measures that must be taken in tunnels with impact ground pressure, and accurately calculating the tunnel's impact resistance is of great significance for the prediction and prevention of impact ground pressure. At present, there are still few methods for calculating impact resistance, and there is only "A method for calculating the impact resistance of tunnel roof anchor support" (application publication number CN 111259542A). This invention calculates the impact resistance of the roof anchor cable support system, mainly considering the kinetic energy and potential energy exerted by the roof on the support system when impact ground pressure occurs. Wang Aiwen et al.

[0003] In the article "Strength Calculation Method of Three-level Energy-absorbing Support for Impact Ground Pressure Tunnels in Coal Mine", a method for calculating the impact resistance of three-level energy-absorbing support formed by "energy-absorbing anchor rods + retractable O-shaped sheds + energy-absorbing hydraulic supports" was mentioned, but the energy absorption and anti-impact energy of this method was only calculated by simple accumulation, which lacks certain rationality; Wu Yongzheng et al. calculated the impact resistance in the article "Principles and Technology of Collaborative Prevention and Control of "Pressure Relief-Support-Protection" in Deep Impact Ground Pressure Tunnels". The individual impact resistance of anchor rods, anchor cables, metal meshes, U-shaped sheds, and hydraulic supports were added together to obtain the impact resistance of the support system, but the important effects of pressure relief, steel belts, and trays on the impact resistance were ignored, and the anti-impact contribution rates of the roof, side and pressure relief measures were not distinguished, and the results obtained were quite different from the actual results.

[0004] In fact, the impact resistance of the tunnel is a macroscopic manifestation of the combined effects of the anchor rods of the support system; the anchor cables and auxiliary system trays, steel belts, and surface protection nets; the hydraulic supports of the advanced support measures, and the pressure relief holes of the pressure relief measures. In general, the existing impact resistance calculation methods have the following deficiencies:

[0005] (1) In the existing impact resistance calculation methods, the impact resistance energies of the supporting components, mainly anchor rods and anchor cables, are simply accumulated. In this type of calculation method, the impact resistance energies of each supporting component are based on empirical values ​​retrieved from literature, and this empirical value is calculated under the action of quasi-static loads on the supporting components. On the one hand, the impact resistance of the supporting components under dynamic load impact is not fully considered. On the other hand, with the improvement of the processing materials of the supporting structure and the improvement of its mechanical properties, this empirical value can no longer reflect the impact resistance of the current anchor rod and cable support materials.

[0006] (2) Incomplete consideration of support factors. The existing impact resistance calculation method only considers the impact resistance of anchor rods and anchor cables, and does not consider the impact resistance of supporting components such as trays, steel belts, and surface protection nets. At the same time, it ignores the energy that can be absorbed by the advanced support measures and the deformation of the surrounding rock itself.

[0007] (3) For rock burst tunnels, large-diameter drilling to relieve pressure has become a necessary measure. It absorbs energy through shrinkage and deformation, thereby improving the impact resistance of the support system. This is a factor that must be considered in the calculation of the tunnel's impact resistance. However, the existing impact resistance calculation methods do not calculate the energy that can be absorbed by the pressure relief holes. Summary of the invention

[0008] In view of various deficiencies in existing methods for calculating impact resistance, the present invention proposes a method for accurately calculating the impact resistance of coal mine tunnels, which calculates the impact resistance of tunnels in a more accurate and reasonable way.

[0009] Technical solution: A method for accurately calculating the impact resistance of coal mine tunnels, comprising the following steps:

[0010] Step 1: Investigate on-site engineering geological conditions and specific tunnel support parameters

[0011] ① Investigate and determine the support parameters of the on-site tunnel, including: the number of single-row anchors in the roof n dg ; Number of single-row anchor cables on the top plate n ds ; Roof anchor support row spacing c; Tunnel width a; Number of single-row anchors in the sidewall n bg ; Number of single-row anchor cables in the side part n bs ; Anchor support row spacing d; Tunnel height b;

[0012] ②Investigate and determine the pressure relief parameters of the on-site tunnel, including: the area S of the pressure relief hole k , the depth of the pressure relief hole h k , the diameter of the pressure relief hole d, the spacing of the pressure relief holes l;

[0013] ③Investigate and determine the engineering geological parameters of the on-site tunnel, including: the vertical stress σ h , the surrounding rock density γ of the tunnel, the tunnel burial depth h, the periodic pressure step distance L of the tunnel, and the overall stability of the tunnel;

[0014] ④ Investigate the parameters of the advanced support measures, including: the number of advanced supports within the pressure step range of one cycle n z , the stiffness K of the hydraulic support, the effective support area S of the support group, and the displacement W of the hydraulic support.

[0015] Step 2: Determination of impact component energy

[0016] The anti-impact and support components used on site are sampled and subjected to dynamic impact tests to measure the energy that each support component can absorb, providing reliable basic data for the next step of calculating the energy that the overall support structure can absorb.

[0017] Step I: Conduct dynamic load impact test on anchor rods and anchor cables used in the support site

[0018] The specific steps are as follows:

[0019] ① Sampling: sampling is carried out from the roof anchor rods, roof anchor cables, side anchor rods and side anchor cables at the rock burst tunnel support site. The number of sampling for the roof anchor rods and roof anchor cables is not less than 5, the number of sampling for the side anchor rods and side anchor cables is not less than 10, and the sampling length of a single specimen is 50 mm;

[0020] ② Test: The samples obtained in step ① are subjected to dynamic load impact test using Charpy test device to determine the impact absorption index of the support material. The samples are broken by a single impact of the pendulum, and the force-displacement curve is collected and recorded. The V-notch is used for the experiment. The radius of curvature of the notch root is 0.25 mm, the notch depth is 2 mm, and the notch angle is 45 degrees. The detailed test steps are carried out in accordance with the GB2106 metal Charpy (V-notch) impact test determination method. Multiple tests are carried out on the top plate anchor rod, top plate anchor cable, side anchor rod, and side anchor cable. The number of tests on the top plate anchor rod and top plate anchor cable is not less than 5 times respectively, and the number of tests on the side anchor rod and side anchor cable is not less than 10 times respectively;

[0021] ③ Energy calculation: the area enclosed by the force-displacement curve and the coordinate axis is the total impact absorption energy. The average value of multiple test results is taken, and the average energy absorbed by the top plate anchor rod, top plate anchor cable, side anchor rod, and side anchor cable is recorded as: E d杆 、E d索 、E b杆 、E b索 .

[0022] Step II: Use a power machine to perform a dynamic loading test on the pallet and steel belt. The specific steps are as follows:

[0023] ① Sampling: sampling the roof anchor tray, roof anchor cable tray, side anchor tray, side anchor cable tray, roof steel belt, and side steel belt used on the rock burst tunnel site, where the number of samples of the roof anchor tray and roof anchor cable tray shall be no less than 3 each, the total length of the roof steel belt sampling shall be no less than 200mm, and the number of samples shall be no less than 5; the number of samples of the side anchor tray and side anchor cable tray shall be no less than 6 each, the total length of the side steel belt sampling shall be no less than 400mm, and the number of samples shall be no less than 10;

[0024] ② Test: The multiple samples obtained in step ① are subjected to loading test by using electro-hydraulic servo hydraulic universal testing machine JL-WAW60, with a loading rate of 0.02-0.05 mm / min, and the change law of mechanical properties during loading is analyzed, and the maximum bearing capacity and deformation height index of the top plate anchor tray, top plate anchor cable tray, top plate steel belt, side anchor tray, side anchor cable tray, and side steel belt are obtained respectively, and their stress-strain curves are obtained, wherein the number of tests of the top plate anchor tray and the top plate anchor cable tray shall not be less than 3 times, and the number of tests of the top plate steel belt shall not be less than 5 times; the number of tests of the side anchor tray and the side anchor cable tray shall not be less than 6 times, and the number of tests of the side steel belt shall not be less than 10 times;

[0025] ③ Energy calculation: According to the stress-strain curve obtained in step ②, the area enclosed by the stress-strain curve corresponding to each support material and the coordinate axis is calculated, that is, the absorbed energy value. The average value of multiple test results is taken, and the energy absorbed by the top plate anchor tray, top plate anchor cable tray, top plate steel belt, side anchor tray, side anchor cable tray, and side steel belt is recorded as: E d杆托 、E d索托 、E d钢带 、E b杆托 、E b索托 、E b钢带 ;

[0026] Step III: Impact test of protective net

[0027] Use a cage-type fence impact tester to conduct an impact test on the warp and weft net or engineering plastic net used on site to obtain the energy that the fence can absorb. The specific steps are as follows:

[0028] ① Take materials: Take at least 3 4m high concrete blocks from the roof of the rock burst tunnel support site. 2 The protective net is used as the test material for the top plate, and then no less than 6 4m 2 The protective net is used as the test material for the help part;

[0029] ② Impact test of the protective net. For the test materials obtained in step ①, a cage-type football net impact tester is used to conduct a cage-type net impact test to obtain the maximum load that the protective net can withstand with displacement changes, obtain its stress-strain curve, and calculate the absorbed energy index of the protective net during the impact process. The top plate protective net is tested at least 3 times, and the side protective net is tested at least 6 times;

[0030] ③ Energy calculation: According to the stress-strain curves of the roof and side protection nets, the stress-strain curves are integrated to find the area enclosed by the stress-strain curve and the coordinate axis, that is, the energy that can be absorbed. The average value of multiple test results is taken, and the energy that can be absorbed by the roof and side protection nets is calculated as E. dw、E bw ;

[0031] Step 3: Calculate the energy that can be absorbed by the tunnel support structure per unit area

[0032] Step I: The energy of the top plate is calculated according to the following formula:

[0033] E d =[n dg ×(E d杆 +E d杆托 )+n ds ×(E d索 +E d索托 )+E d钢带 ] / (a×c)+E dw (1)

[0034] Where: E d is the energy that can be absorbed by the tunnel roof support structure per unit area; n dg is the number of single-row anchor rods on the top plate; E d杆 E is the energy that can be absorbed by a single anchor rod in the roof; d杆托 Energy that can be absorbed by the tray supporting the roof anchor; n ds is the number of single-row anchor cables on the top plate; E d索 The energy that can be absorbed by a single anchor cable on the top plate; E d索托 The energy that can be absorbed by the tray supporting the top plate anchor cable; E d钢带 is the energy that the roof steel belt can absorb; a is the tunnel width; c is the spacing of the roof anchor support; E dw It is the energy that can be absorbed by the protective net per unit area of ​​the roof.

[0035] Step II: The energy of the gang is calculated according to the following formula:

[0036] E b =[n bg ×(E b杆 +E b杆托 )+n bs ×(E b索 +E b索托 )+E b钢带 ] / (b×d)+E bw (2)

[0037] Where: E b is the energy that can be absorbed by the tunnel support structure per unit area; n bg E is the number of single-row anchor rods in the side section; b杆 The energy that can be absorbed by a single anchor rod in the side; E b杆托 Energy that can be absorbed by the tray supporting the side anchor; n bs E is the number of single-row anchor cables in the side section;b索 The energy that can be absorbed by a single anchor cable in the gangway; E b索托 The energy that can be absorbed by the tray supporting the anchor cable; E b钢带 is the energy that the steel belt of the side can absorb; b is the tunnel height; d is the spacing of the anchor support rows of the side; E bw It is the energy that can be absorbed by the protective net per unit area of ​​the helper.

[0038] Step III: Calculate the energy that can be absorbed by the pressure relief holes used on site in the tunnel

[0039] The energy that can be absorbed by the pressure relief borehole is calculated according to the following formula:

[0040] E k =S k ×k b ×h k ×σ h / (l×b) (3)

[0041]

[0042] σ h =γh (5)

[0043] Where: E k is the energy that can be absorbed by the pressure relief borehole per unit area, S k is the area of ​​the pressure relief hole, h k is the depth of the pressure relief hole, k b The closure coefficient of the pressure relief hole is 0.1% to 0.2%, σ h is the vertical stress at the drilling site, π is the circumference of the circle and is taken as 3.14, γ is the bulk density and is taken as 25-27 kN / m 3 , h is the buried depth of the tunnel, d is the diameter of the pressure relief hole, b is the height of the tunnel, and l is the spacing between the pressure relief holes.

[0044] Step IV: Energy calculation of hydraulic support and other advanced support measures

[0045] The energy that the hydraulic support can absorb is calculated according to the following formula:

[0046]

[0047] Where: E y is the average energy that the hydraulic support can absorb per unit area, n z is the number of leading supports within one cycle of pressure step, K is the stiffness of the hydraulic support, which is 0.14×10 8 (N / m 2 ), S is the effective support area of ​​the support group, which is 0.7-0.8 of the support top contact area; W is the displacement of the hydraulic support; a is the width of the tunnel; L is the periodic pressure step distance of the tunnel.

[0048] Step 4: Comprehensive calculation of tunnel impact resistance

[0049] Step I: Determine the weight coefficient

[0050] According to the stability of the surrounding rock of the tunnel, determine the energy E that the roof support structure can absorb per unit area. d , the energy that can be absorbed by the tunnel side structure per unit area E b ; The energy that can be absorbed by the pressure relief drilling hole per unit area E k The weights of the three are shown in Table 1, where α is E d The weight of E b The weight of E k The weight occupied.

[0051] Table 1 Weight impact factor distribution table

[0052] Stability of surrounding rock in tunnel α β γ Very stable 0.4 0.4 0.2 Stablize 0.5 0.3 0.2 Moderately stable 0.6 0.3 0.1 Unstable 0.7 0.2 0.1

[0053] Step II: Weight distribution calculation

[0054] The weight factors α, β, and γ form a matrix A

[0055]

[0056] The energy E that can be absorbed by the roof support structure per unit area d , the energy that can be absorbed by the tunnel side structure per unit area E b ; The energy that can be absorbed by the pressure relief drilling hole per unit area E k The matrix B is composed of

[0057]

[0058] Step III: Calculate the impact resistance per unit area of ​​the alley after assigning weights

[0059]

[0060] In the formula, E z It is the impact resistance per unit area of ​​the tunnel after weights are assigned.

[0061] Step IV: Calculate the comprehensive impact resistance of the roadway

[0062] According to the first step of investigating the roof conditions of the tunnel, the periodic pressure step length L of the tunnel is calculated. Taking the periodic pressure step length range as a whole, the comprehensive impact resistance of the tunnel is calculated as follows:

[0063] E L =[(a+2b)×Ez +a×E y ]×L (9)

[0064] In the formula, E L is the comprehensive impact resistance of the tunnel with a periodic pressure step length; a is the tunnel width, b is the tunnel height; E z E is the impact resistance per unit area of ​​the tunnel after weight allocation; y is the average energy that the hydraulic support can absorb per unit area; L is the periodic pressure step distance under the roof condition.

[0065] Beneficial effects:

[0066] (1) The calculation method of the present invention clarifies the details of the materials, experimental equipment, loading methods, etc. in the experiment by conducting dynamic load impact tests on the materials of each support component on site, and can obtain the true impact energy value. According to the stability of the surrounding rock, the energy that can be absorbed by each support component and pressure relief hole of the top plate and the side is weighted and distributed. The basic data source is real and valid, and the energy calculation method is scientific and reasonable, forming an accurate and systematic calculation method for impact resistance.

[0067] (2) The existing methods for calculating impact resistance have not considered the role of pressure relief measures. The present invention proposes a specific calculation formula for the energy absorbed by the pressure relief hole, and performs a comprehensive weighted calculation of the impact resistance energy of the pressure relief measures according to the surrounding rock conditions, comprehensively considering the influence of the pressure relief measures on the impact resistance of the tunnel.

[0068] (3) Comprehensively consider the effects of support components. The existing impact resistance calculation method only considers the energy calculation of some anti-impact support components such as anchor rods and anchor cables, while the method described in the present invention comprehensively and fully considers the impact resistance of each support structure including anchor rods, anchor cables, trays, steel belts, and surface protection nets on the top plate and the side, and fully considers the energy that can be absorbed by the advanced support measures, so that the calculation results are more in line with the actual situation on site. DETAILED DESCRIPTION

[0069] The following is a further explanation of this patent with reference to specific examples:

[0070] A mine is a mine with rock burst risk, and strong support and large-diameter drilling are carried out on the tunnels with rock burst risk. Now, according to the calculation method of the present invention, the rock burst resistance is calculated.

[0071] Step 1: Investigate relevant design parameters.

[0072] ①Investigate and determine the specific support parameters of the on-site tunnel: the number of single-row anchors in the roof n dg 7; the number of single-row anchor cables on the top plate is n ds2; the top plate anchor support row spacing c is 0.95m; the tunnel width a is 5.2m; the number of single-row anchors in the side is n bg 5; the number of single-row anchor cables in the side part is n bs There are 2 anchors; the spacing d of the side anchor support is 0.90m; the tunnel height b is 3.7m;

[0073] ②Investigate and determine the specific pressure relief parameters of the on-site tunnel: the depth of the pressure relief hole h k The diameter of the pressure relief hole is 20m, the diameter of the pressure relief hole is 150mm, and the spacing between the pressure relief holes is 2.0m.

[0074] ③Investigate and determine the specific engineering geological parameters of the on-site tunnel, including: the surrounding rock of the tunnel has a bulk density of γ of 25kN / m 3 The tunnel burial depth h is 750m, the tunnel periodic pressure step distance L is 40m, and the overall stability of the tunnel is a stable tunnel.

[0075] ④ Investigate the specific parameters of the advanced support measures: the number of advanced supports within the pressure step range of one cycle n z There are 20 groups, and the stiffness K of the hydraulic support is 0.14×10 8 (N / m 2 ), the effective support area S of the support group is 4.8m, and the displacement W of the hydraulic support is 300mm.

[0076] Step 2: Determination of impact component energy.

[0077] Step I: Conduct dynamic load impact test on the anchor rods and cables used at the support site.

[0078] ① Material collection. Take 5 samples from the roof anchor and roof anchor cable at the rock burst tunnel support site, and then take 10 samples from the anchor rods at the side. The number of samples of the anchor cables at the side is also 10. The sampling length of all samples is guaranteed to be 50mm. ② Test. The samples obtained in step ① are tested using the Charpy test device. ③ Energy calculation. Integrate the test curve to obtain the 5 test energies of the roof anchor, and take the average value to finally determine the energy E that the roof anchor can absorb d杆 The energy absorbed by the top plate anchor cable is 3.5 kJ / root. d索 The energy that the anchor bolt can absorb is 8.2 kJ / root. b杆 The energy that can be absorbed by the anchor cable is 3.1 kJ / root. b索 It is 7.8kJ / root.

[0079] Step II: Use a power machine to perform dynamic loading tests on the pallet and steel belt.

[0080] ① Material collection. Take 3 roof anchor trays, 3 roof anchor cable trays, 6 side anchor trays, 6 side anchor cable trays, 5 samples with a total length of 200mm from the roof steel strip, and 10 samples with a total length of 400mm from the side from the impact ground pressure tunnel site. ② Test. Carry out loading tests on the multiple samples obtained in step ①. ③ Energy calculation. Take the average value of the multiple test results to obtain the energy E that the roof anchor tray can absorb. d杆托 The energy E that can be absorbed by the top plate anchor cable tray is 2.7 kJ / piece. d索托 The energy that the top steel strip can absorb is 6.3 kJ / piece. d钢带 The energy that the anchor tray can absorb is 4.6 kJ / bar. b杆托 The energy E that can be absorbed by the anchor cable tray is 2.5 kJ / piece. b索托 The energy that the steel belt of the side can absorb is 5.9kJ / piece. b钢带 It is 4.7kJ / bar.

[0081] Step III: Impact test of protective net.

[0082] ① Material collection. Take three 4m 2 The protective net, and then remove 6 4m 2 The protective net of the roof plate is used as the test material for the side part. ② Impact test of the protective net. The test material obtained in step ① is subjected to the cage-type fence impact test. ③ Calculate the energy and process the results. Integrate the stress-strain curves of the roof protective net and the side protective net, and take the average value of the multiple test results of the roof and side protective net to obtain the energy E that the roof protective net can absorb. dw 0.53 kJ / m 2 , the energy that the protective net can absorb E bw 0.54 kJ / m 2 .

[0083] Step 3: Calculate the energy that can be absorbed by the tunnel support structure per unit area.

[0084] Step I: The energy of the top plate is calculated according to formula (1):

[0085] E d =[n dg ×(E d杆 +E d杆托 )+n ds ×(E d索 +E d索托 )+E d钢带 ] / (a×c)+E dw (1)

[0086] According to the dynamic load test results of the mine, the energy E that can be absorbed by the roof support structure per unit area can be obtained by substituting relevant energy values. d for:

[0087] E d =[7×(3.5+2.7)+2×(8.2+6.3)+4.6] / (5.2×0.95)+0.53=16.12kJ / m 2

[0088] Step II: The energy of the shank is calculated according to formula (2):

[0089] E b =[n bg ×(E b杆 +E b杆托 )+n bs ×(E b索 +E b索托 )+E b钢带 ] / (b×d)+E bw (2)

[0090] According to the dynamic load test results of the mine, the energy E that can be absorbed by the support structure per unit area can be obtained by inputting relevant energy parameters. b for:

[0091] E b =[5×(3.1+2.5)+2×(7.8+5.9)+4.7] / (3.7×0.90)+0.54=18.59kJ / m 2

[0092] Step III: Calculate the energy that can be absorbed by the pressure relief holes taken on site.

[0093] According to the results of the first step of investigation, the tunnel depth h is 750m; the bulk density γ is 25kN / m 3 ; Pi is 3.14; the diameter of the pressure relief hole d is 0.15m; the closure coefficient k b Take 0.2%; the depth of the pressure relief hole h k is 20m; the hole spacing is 2.0m; the tunnel height is 3.7m. According to formulas (3) to (5), the energy that can be absorbed by the pressure relief borehole per unit area is:

[0094]

[0095] σ h =25×750=18.75MPa

[0096] E k=0.035325×20×0.2%×18.75÷(2.0×3.7)=3.58kJ / m 2

[0097] Step IV: Combine calculations with advanced support measures such as hydraulic supports.

[0098] According to formula (6), the energy that the hydraulic support can absorb is calculated:

[0099]

[0100]

[0101] Step 4: Comprehensive calculation of tunnel impact resistance.

[0102] According to the energy calculation formula in the third step, determine the energy E that the roof support structure can absorb d 16.12 kJ / m 2 , the energy that the tunnel side structure can absorb E b 18.59 kJ / m 2 ; Energy E absorbed by the pressure relief drilling k 3.58 kJ / m 2 .

[0103] Step I: Determine the weight coefficient. According to the stable type of the tunnel surrounding rock, refer to the weight influence factor allocation table 1 and determine the weight coefficients α, β, and γ as 0.5, 0.3, and 0.2 respectively.

[0104] Step II: Weight distribution calculation.

[0105] The weight factors α, β, and γ form a matrix A

[0106]

[0107] The energy E absorbed by the support structure per unit area d , E b , E k Make up the matrix B.

[0108]

[0109] Step III: Calculate the impact resistance per unit area of ​​the tunnel after weight allocation. Substituting the weight factor and energy parameter into formula (8) yields:

[0110]

[0111] Step IV: Calculate the comprehensive impact resistance of the tunnel.

[0112] According to the results of the first step investigation, the periodic pressure step length L is 40m, so the periodic pressure step length range is taken as a whole. The comprehensive impact resistance of the tunnel is calculated according to formula (9):

[0113] E L =[(5.2+2×3.7)×14.353+5.2×8.07]×40=8.914×10 6 J

[0114] Therefore, the impact resistance of the coal mine tunnel is: it can withstand 8.914×10 6 J of impact energy.

Claims

1. A method for accurately calculating the impact resistance of coal mine tunnels, characterized in that: The following steps are involved: Step 1: Determination of impact component energy The anti-impact and support components used on site were sampled and subjected to dynamic impact tests to obtain the average energy that can be absorbed by the top plate anchor rod, top plate anchor cable, side anchor rod, and side anchor cable: E d杆 、E d索 、E b杆 、E b索 The energy that can be absorbed by the top plate anchor tray, top plate anchor cable tray, top plate steel belt, side anchor tray, side anchor cable tray, and side steel belt is: E d杆托 、E d索托 、E d钢带 、E b杆托 、E b索托 、E b钢带 ; The energy that the top plate and the side protection net can absorb is E dw 、E bw ; Step 2: Calculate the energy that can be absorbed by the tunnel support structure per unit area Step I: Calculate the energy that can be absorbed by the tunnel roof support structure per unit area. The calculation formula is as follows: AND d =[n dg ×(And d杆 +E d杆托 )+n ds ×(And d索 +E d索托 )+E d钢带 ] / (a×c)+E dw (1) Where: E d is the energy that can be absorbed by the tunnel roof support structure per unit area; n dg is the number of single-row anchor rods on the top plate; E d杆 E is the energy that can be absorbed by a single anchor rod in the roof; d杆托 Energy that can be absorbed by the tray supporting the roof anchor; n ds is the number of single-row anchor cables on the top plate; E d索 The energy that can be absorbed by a single anchor cable on the top plate; E d索托 The energy that can be absorbed by the tray supporting the top plate anchor cable; E d钢带 is the energy that the roof steel belt can absorb; a is the tunnel width; c is the spacing of the roof anchor support; E dw It is the energy that can be absorbed by the surface protection net per unit area of ​​the roof; Step II: Calculate the energy that can be absorbed by the tunnel support structure per unit area. The calculation formula is as follows: AND b =[n bg ×(And b杆 +E b杆托 )+n bs ×(And b索 +E b索托 )+E b钢带 ] / (b×d)+E bw (2) Where: E b is the energy that can be absorbed by the tunnel support structure per unit area; n bg E is the number of single-row anchor rods in the side section; b杆 The energy that can be absorbed by a single anchor rod in the side; E b杆托 Energy that can be absorbed by the tray supporting the side anchor; n bs E is the number of single-row anchor cables in the side section; b索 The energy that can be absorbed by a single anchor cable in the gangway; E b索托 The energy that can be absorbed by the tray supporting the anchor cable; E b钢带 is the energy that the steel belt of the side can absorb; b is the tunnel height; d is the spacing of the anchor support; E bw It is the energy that can be absorbed by the protective net per unit area of ​​the gang part; Step III: Calculate the energy that can be absorbed by the pressure relief borehole per unit area at the tunnel site. The calculation formula is as follows: E k =S k ×k b ×h k ×σ h / (l×b) (3) s h =γh (5) Where: E k is the energy that can be absorbed by the pressure relief borehole per unit area, S k is the area of ​​the pressure relief hole, h k is the depth of the pressure relief hole, k b The closure coefficient of the pressure relief hole is 0.1% to 0.2%, σ h is the vertical stress at the drilling site, π is the circumference of the circle and is taken as 3.14, γ is the bulk density and is taken as 25-27 kN / m 3 , h is the buried depth of the tunnel, d is the diameter of the pressure relief hole, b is the height of the tunnel, and l is the spacing between the pressure relief holes; Step IV: Calculate the energy that can be absorbed per unit area by the hydraulic support advance support measures. The calculation formula is as follows: Where: E y is the average energy that the hydraulic support can absorb per unit area, n z is the number of leading supports within one cycle of pressure step, K is the stiffness of the hydraulic support, which is 0.14×10 8 (N / m 2 ), S is the effective support area of ​​the support group, which is 0.7-0.8 of the support top contact area; W is the displacement of the hydraulic support; a is the width of the lane; L is the periodic pressure step of the lane; Step 3: Comprehensive calculation of tunnel impact resistance Step I: Determine the weight coefficient According to the stability of the surrounding rock of the tunnel, determine the energy E that the roof support structure can absorb per unit area. d , the energy that can be absorbed by the tunnel side structure per unit area E b ; The energy that can be absorbed by the pressure relief drilling hole per unit area E k The weights of the three, where α is E d The weight of E b The weight of E k The weight of the surrounding rock of the tunnel is divided into four types: very stable, stable, moderately stable and unstable. When the surrounding rock of the tunnel is very stable, α = 0.4, β = 0.4, γ = 0.2; when the surrounding rock of the tunnel is stable, α = 0.5, β = 0.3, γ = 0.2; when the surrounding rock of the tunnel is moderately stable, α = 0.6, β = 0.3, γ = 0.1; when the surrounding rock of the tunnel is unstable, α = 0.7, β = 0.2, γ = 0.1; Step II: Weight distribution calculation, weight factors α, β, γ form matrix A The energy E that can be absorbed by the roof support structure per unit area d , the energy that can be absorbed by the tunnel side structure per unit area E b ; The energy that can be absorbed by the pressure relief drilling hole per unit area E k Composition matrix B Step III: Calculate the impact resistance per unit area of ​​the alley after assigning weights In the formula, E z is the impact resistance per unit area of ​​the tunnel after weight allocation; Step IV: Calculate the comprehensive impact resistance of the roadway According to the roof conditions of the tunnel, the periodic pressure step length L of the tunnel is calculated. Taking the periodic pressure step length range as a whole, the comprehensive impact resistance of the tunnel is calculated as follows: AND L =[(a+2b)×E z +a×E y ]×L (9) In the formula, E L is the comprehensive impact resistance of the tunnel with a periodic pressure step length; a is the tunnel width, b is the tunnel height; E z E is the impact resistance per unit area of ​​the tunnel after weight allocation; y is the average energy that the hydraulic support can absorb per unit area; L is the periodic pressure step distance under the roof condition.

2. The method for accurately calculating the impact resistance of coal mine tunnels according to claim 1 is characterized in that: Conduct dynamic load impact tests on anchor rods and anchor cables used in the support site to obtain the average energy E absorbed by the top plate anchor rods, top plate anchor cables, side anchor rods, and side anchor cables. d杆 、E d索 、E b杆 、E b索 , the specific steps are: ① Sampling: sampling from the roof anchor rods, roof anchor cables, side anchor rods, and side anchor cables at the rock burst tunnel support site; ② Test: The samples obtained in step ① are subjected to dynamic load impact test using Charpy test device to determine the impact absorption index of the support material. The samples are broken by a single impact of the pendulum, and the force-displacement curve is collected and recorded. The detailed test steps are carried out according to the GB2106 metal Charpy V-notch impact test determination method. Multiple tests are carried out on the top plate anchor rod, top plate anchor cable, side anchor rod, and side anchor cable; ③ Energy calculation: the area enclosed by the force-displacement curve and the coordinate axis is the total impact absorption energy. The average value of multiple test results is taken, and the average energy absorbed by the top plate anchor rod, top plate anchor cable, side anchor rod, and side anchor cable is recorded as: E d杆 、E d索 、E b杆 、E b索 .

3. The method for accurately calculating the impact resistance of coal mine tunnels according to claim 2 is characterized in that: The number of sampling for the top plate anchor rods and top plate anchor cables shall be no less than 5 each, the number of sampling for the side anchor rods and side anchor cables shall be no less than 10 each, and the sampling length of a single specimen shall be 50 mm.

4. A method for accurately calculating the impact resistance of coal mine tunnels according to claim 2 or 3, characterized in that: When using the V-notch impact test, the curvature radius of the notch root is 0.25mm, the notch depth is 2mm, the notch angle is 45 degrees, the test times of the top plate anchor rod and top plate anchor cable are not less than 5 times respectively, and the test times of the side anchor rod and side anchor cable are not less than 10 times respectively.

5. The method for accurately calculating the impact resistance of coal mine tunnels according to claim 1 is characterized in that: A dynamic loading test was carried out on the pallet and steel belt using a power machine to obtain the energy E absorbed by the top plate anchor pallet, top plate anchor cable pallet, top plate steel belt, side anchor pallet, side anchor cable pallet and side steel belt. d杆托 、E d索托 、E d钢带 、E b杆托 、E b索托 、E b钢带 ; The specific steps are: ① Sampling: sampling the roof anchor tray, roof anchor cable tray, side anchor tray, side anchor cable tray, roof steel belt, and side steel belt used in the rock burst tunnel site; ② Test: The multiple samples obtained in step ① were subjected to loading test using electro-hydraulic servo hydraulic universal testing machine JL-WAW60, and the change law of mechanical characteristics during loading was analyzed. The maximum bearing capacity and deformation height index of the top plate anchor tray, top plate anchor cable tray, top plate steel belt, side anchor tray, side anchor cable tray, and side steel belt were obtained, and their stress-strain curves were obtained. ③ Energy calculation: According to the stress-strain curve obtained in step ②, the area enclosed by the stress-strain curve corresponding to each support material and the coordinate axis is calculated, that is, the absorbed energy value. The average value of multiple test results is taken, and the energy absorbed by the top plate anchor tray, top plate anchor cable tray, top plate steel belt, side anchor tray, side anchor cable tray, and side steel belt is recorded as: E d杆托 、E d索托 、E d钢带 、E b杆托 、E b索托 、E b钢带 .

6. A method for accurately calculating the impact resistance of coal mine tunnels according to claim 5, characterized in that: The sampling quantity of the top plate anchor rod tray and the top plate anchor cable tray shall be no less than 3 each, the total sampling length of the top plate steel strip shall not be less than 200mm, and the sampling quantity shall be no less than 5; the sampling quantity of the side anchor rod tray and the side anchor cable tray shall be no less than 6 each, the total sampling length of the side steel strip shall not be less than 400mm, and the sampling quantity shall be no less than 10.

7. A method for accurately calculating the impact resistance of coal mine tunnels according to claim 5 or 6, characterized in that: The loading rate of the loading test is 0.02-0.05 mm / min; the test times of the top plate anchor tray and the top plate anchor cable tray are not less than 3 times each, and the test times of the top plate steel strip are not less than 5 times; the test times of the side anchor tray and the side anchor cable tray are not less than 6 times each, and the test times of the side steel strip are not less than 10 times.

8. The method for accurately calculating the impact resistance of coal mine tunnels according to claim 1 is characterized in that: The cage-type fence impact test machine was used to conduct an impact test on the protective net used on site, and the energy that the top plate and the side protective net can absorb was obtained as E. dw 、E bw , the specific steps are as follows: ① Obtain materials: remove the protective nets from the roof and side of the rock burst tunnel support site as test materials; ② Impact test of the protective net: for the test materials obtained in step ①, a cage-type football net impact tester is used to conduct a cage-type net impact test, obtain the maximum load that the protective net can withstand with displacement changes, obtain its stress-strain curve, and calculate the absorbed energy index of the protective net during the impact process; ③ Energy calculation: According to the stress-strain curves of the roof and side protection nets, the stress-strain curves are integrated to find the area enclosed by the stress-strain curves and the coordinate axis, that is, the energy that can be absorbed; the average value of multiple test results is taken, and the energy that can be absorbed by the roof and side protection nets is recorded as E dw 、E bw .

9. A method for accurately calculating the impact resistance of coal mine tunnels according to claim 8, characterized in that: Take no less than three 4m 2 The protective net is used as the test material for the top plate, and then no less than 6 4m 2 The protective net is used as the test material for the help part.

10. A method for accurately calculating the impact resistance of coal mine tunnels according to claim 8 or 9, characterized in that: The top plate protection net shall be tested no less than 3 times, and the side protection net shall be tested no less than 6 times.

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