阅读说明：本技术 一种煤矿巷道抗冲击能力精准计算方法 (Accurate calculation method for impact resistance of coal mine tunnel ) 是由 张广超 陶广哲 李友 于善昌 赵德帅 尹茂盛 李瑞明 陈淼 于 2021-07-14 设计创作，主要内容包括：一种煤矿巷道抗冲击能力精准计算方法,通过对现场各支护构件取材进行动载冲击试验,明确了实验中的取材、实验设备、加载方式等细节内容,可得到真实抗冲击能量数值,并根据围岩稳定性状况,对顶板、帮部的各支护构件及卸压孔所能吸收的能量进行权重分配,基础数据来源真实有效,能量计算方法科学合理；提出了卸压孔吸收能量的具体计算公式,并根据围岩状况将卸压措施抗冲能量进行综合加权计算,全面的考虑了卸压措施对巷道抗冲击能力的影响关系；全面充分的考虑了顶板及帮部包括锚杆、锚索、托盘、钢带、护表网在内的各个支护结构的抗冲击能力,并充分考虑了超前支护措施所能吸收的能量,使得计算结果更符合现场实际情况。(A coal mine tunnel shock resistance accurate calculation method, through drawing materials to every support member at scene and carrying on the dynamic load impact test, have made clear details such as drawing materials, experimental facilities, loading mode in the experiment, can get the true impact energy numerical value, and according to the stability situation of the surrounding rock, carry on the weight distribution to the energy that every support member and relief vent of roof, upper can absorb, the basic data source is true and effective, the energy calculation method is scientific and reasonable; a specific calculation formula for energy absorption of the pressure relief holes is provided, impact energy of pressure relief measures is comprehensively weighted and calculated according to the surrounding rock conditions, and the influence relationship of the pressure relief measures on the impact resistance of the roadway is comprehensively considered; the impact resistance of each supporting structure of the top plate and the side part, including the anchor rod, the anchor cable, the tray, the steel belt and the surface protecting net, is fully considered, and the energy absorbed by advanced supporting measures is fully considered, so that the calculation result is more in line with the actual situation on site.)

1. The method for accurately calculating the impact resistance of the coal mine tunnel is characterized by comprising the following steps of:

the first step is as follows: impact member energy determination

Draw materials for the anti-impact and supporting components used on site, perform dynamic impact experiments, and respectively obtain the average energy which can be absorbed by the roof anchor rod, the roof anchor cable, the side anchor rod and the side anchor cable as follows: e_{D rod}、E_{D cable}、E_{b rod}、E_{b cable}(ii) a Roof stock tray, roof anchor rope tray, roof steel band, group's stock tray, group's anchor rope tray, group's steel band can the absorptive energy be: e_{D pole holder}、E_{D cable support}、E_{d steel band}、E_{b pole holder}、E_{b cable support}、E_{b steel band}(ii) a The energy absorbed by the top plate and the upper part protective surface net is E_dw、E_bw；

The second step is that: calculating the energy that a roadway support structure of unit area can absorb

Step I: the energy which can be absorbed by the roadway roof supporting structure in unit area is calculated according to the following calculation formula:

E_d＝[n_dg×(E_{d rod}+E_{D pole holder})+n_ds×(E_{D cable}+E_{D cable support})+E_{d steel band}]/(a×c)+E_dw (1)

In the formula: e_dIs the energy that the supporting structure of the roadway roof in unit area can absorb; n is_dgThe number of the roof single-row anchor rods; e_{D rod}The energy which can be absorbed by a single anchor rod of the top plate; e_{D pole holder}The energy absorbed by the tray matched with the roof bolt; n is_dsThe number of the single-row anchor cables of the top plate; e_{D cable}The energy absorbed by a single anchor cable on the top plate; e_{D cable support}The energy absorbed by the tray matched with the top plate anchor cable; e_{d steel band}The energy that the steel strip of the top plate can absorb; a is the width of the roadway; c isSupporting row spacing by roof bolts; e_dwThe energy absorbed by the surface protecting net in the unit area of the top plate;

step II: the energy which can be absorbed by the supporting structure of the roadway side part in unit area is calculated according to the following calculation formula:

E_b＝[n_bg×(E_{b rod}+E_{b pole holder})+n_bs×(E_{b cable}+E_{b cable support})+E_{b steel band}]/(b×d)+E_bw (2)

In the formula: e_bIs the energy that the supporting structure of the roadway side part in unit area can absorb; n is_bgThe number of the single-row anchor rods on the upper part; e_{b rod}The energy which can be absorbed by a single anchor rod on the upper part; e_{b pole holder}The energy absorbed by the tray matched with the upper anchor rod; n is_bsThe number of the single-row anchor cables on the upper part is set; e_{b cable}Energy which can be absorbed by a single anchor cable at the upper part; e_{b cable support}The tray matched with the anchor cable at the upper part can absorb energy; e_{b steel band}The energy which can be absorbed by the upper steel belt; b is the height of the roadway; d is the anchor rod side support row spacing; e_bwThe energy which can be absorbed by the upper part unit area of the watch protecting net;

step III: and (3) calculating the energy which can be absorbed by the pressure relief drill hole in unit area of the roadway site, wherein the calculation formula is as follows:

E_k＝S_k×k_b×h_k×σ_h/(l×b) (3)

σ_h＝γh (5)

in the formula: e_kEnergy, S, absorbed per unit area of pressure relief borehole_kArea of pressure relief holes, h_kDepth of relief hole, k_bThe closing coefficient of the pressure relief hole is 0.1-0.2 percent, sigma_hThe vertical stress at the drill hole is represented by pi being 3.14 in circumferential ratio and gamma being 25-27 kN/m in volume weight³H is the buried depth of the roadway, d is the diameter of the pressure relief hole,b is the height of the roadway, and l is the distance between the pressure relief holes;

step IV: the energy which can be absorbed by the unit area of the advance support measure of the hydraulic support is calculated, and the calculation formula is as follows:

in the formula: e_yAverage energy that a unit area of the hydraulic support can absorb, n_zThe number of the forepoling in the step pitch of one period of pressure coming is taken as K is the rigidity of the hydraulic bracket, and 0.14 multiplied by 10 is taken as⁸(N/m²) S is the effective supporting area of the bracket group, and 0.7-0.8 of the contact area of the bracket is taken; w is the displacement of the hydraulic support; a is the width of the roadway; l is the periodic pressure step pitch of the roadway;

the third step: comprehensive calculation of tunnel impact resistance

Step I: determining a weight coefficient

Determining the energy E which can be absorbed by the top plate supporting structure in unit area according to the stability condition of the surrounding rock of the roadway_dEnergy E absorbed by unit area roadway wall structure_b(ii) a Energy E absorbed by unit area of upper pressure relief drilling_kThe weight occupied by the three components, wherein alpha is E_dOccupied weight, beta is E_bThe occupied weight, gamma is E_kThe weight occupied; the stability condition of the surrounding rocks of the roadway is divided into four types of very stable, medium stable and unstable, when the stability condition of the surrounding rocks of the roadway is very stable, alpha is 0.4, beta is 0.4, and gamma is 0.2; when the stability of the surrounding rock of the roadway is stable, alpha is 0.5, beta is 0.3, and gamma is 0.2; when the stability condition of the surrounding rocks of the roadway is moderately stable, alpha is 0.6, beta is 0.3, and gamma is 0.1, when the stability condition of the surrounding rocks of the roadway is unstable, alpha is 0.7, beta is 0.2, and gamma is 0.1;

step II: weight distribution calculation, the weight factors alpha, beta and gamma form a matrix A

Energy E absorbed by a unit area top plate supporting structure_dEnergy E absorbed by unit area roadway wall structure_b(ii) a Energy E absorbed by unit area of upper pressure relief drilling_kForm a matrix B

Step III: calculating the impact resistance of the unit area of the roadway after the weight distribution

In the formula, E_zThe impact resistance of the unit area of the roadway after the weight is distributed;

step IV: calculating comprehensive impact resistance of tunnel

Calculating the periodic pressure step L of the roadway according to the roof condition of the roadway, taking the length range of the periodic pressure step as a whole, and calculating the comprehensive impact resistance of the roadway according to the following formula:

E_L＝[(a+2b)×E_z+a×E_y]×L (9)

in the formula, E_LThe comprehensive impact resistance of the roadway taking the periodic pressure step as the length is realized; a is the width of the roadway, and b is the height of the roadway; e_zThe impact resistance of the unit area of the roadway after the weight is distributed; e_yThe average energy which can be absorbed by the unit area of the hydraulic support; l is the periodic pressure step under the condition of the top plate.

2. The method for accurately calculating the impact resistance of the coal mine tunnel according to claim 1, wherein a dynamic load impact test is performed on anchor rods and anchor cables used in a supporting field to obtain average energy E capable of being absorbed by roof anchor rods, roof anchor cables, side anchor rods and side anchor cables_{D rod}、E_{D cable}、E_{b rod}、E_{b cable}The method comprises the following specific steps:

firstly, materials are taken, and sampling is respectively carried out on a roof anchor rod, a roof anchor cable, an upper anchor rod and an upper anchor cable on a rock burst roadway support site;

secondly, performing a dynamic load impact test on the sample obtained in the first step by using a Charpy test device, determining an impact absorption work index of a supporting material, breaking the sample through one-time impact of a pendulum bob, collecting and recording a force-displacement curve, performing detailed test steps according to a GB2106 metal Charpy V-shaped notch impact test determination method, and performing multiple tests on a roof anchor rod, a roof anchor cable, a side anchor rod and a side anchor cable;

calculating energy, namely the area enclosed by the force-displacement curve and the coordinate axis is the total energy of impact absorption, averaging the test results for many times, and respectively recording the average energy absorbed by the roof anchor rod, the roof anchor cable, the side anchor rod and the side anchor cable as follows: e_{D rod}、E_{D cable}、E_{b rod}、E_{b cable}。

3. The method for accurately calculating the shock resistance of the coal mine tunnel according to claim 2, wherein the sampling number of the roof anchor rods and the roof anchor cables is not less than 5, the sampling number of the side anchor rods and the side anchor cables is not less than 10, and the sampling length of a single sample is 50 mm.

4. The method for accurately calculating the impact resistance of the coal mine tunnel according to claim 2 or 3, wherein when a V-shaped notch impact test is adopted, the curvature radius of the root of the notch is 0.25mm, the depth of the notch is 2mm, the angle of the notch is 45 degrees, the test times of the roof anchor rod and the roof anchor cable are respectively not less than 5 times, and the test times of the side anchor rod and the side anchor cable are respectively not less than 10 times.

5. The method for accurately calculating the impact resistance of the coal mine tunnel according to claim 1, wherein a power machine is adopted to perform power loading test on the tray and the steel beltTesting, respectively obtaining the energy E which can be absorbed by the roof anchor rod tray, the roof anchor cable tray, the roof steel belt, the side anchor rod tray, the side anchor cable tray and the side steel belt_{D pole holder}、E_{D cable support}、E_{d steel band}、E_{b pole holder}、E_{b cable support}、E_{b steel band}(ii) a The method comprises the following specific steps:

firstly, materials are taken, and a top plate anchor rod tray, a top plate anchor cable tray, a side anchor rod tray, a top plate steel belt and a side steel belt which are used in a rock burst roadway site are respectively sampled;

secondly, performing a loading test on the plurality of samples obtained in the first step by adopting an electro-hydraulic servo hydraulic universal testing machine JL-WAW 60, analyzing a change rule of mechanical characteristics in the loading process, and respectively obtaining the maximum bearing capacity and deformation height indexes of a top plate anchor rod tray, a top plate anchor cable tray, a top plate steel belt, an upper part anchor rod tray, an upper part anchor cable tray and an upper part steel belt to obtain a stress-strain curve of the samples;

calculating energy, respectively calculating the area enclosed by the stress-strain curves corresponding to the supporting materials and coordinate axes according to the stress-strain curves obtained in the second step, namely the absorbed energy value, carrying out averaging processing on the test results for a plurality of times, and respectively recording the energy absorbed by the roof anchor rod tray, the roof anchor cable tray, the roof steel belt, the side anchor rod tray, the side anchor cable tray and the side steel belt as follows: e_{D pole holder}、E_{D cable support}、E_{d steel band}、E_{b pole holder}、E_{b cable support}、E_{b steel band}。

6. The method for accurately calculating the impact resistance of the coal mine tunnel according to claim 5, wherein the sampling number of the roof anchor rod tray and the roof anchor cable tray is not less than 3 respectively, the total sampling length of the roof steel belt is not less than 200mm, and the sampling number is not less than 5; the sampling quantity of the side anchor rod tray and the side anchor cable tray is not less than 6 respectively, the total sampling length of the side steel belt is not less than 400mm, and the sampling quantity is not less than 10.

7. The method for accurately calculating the impact resistance of the coal mine tunnel according to claim 5 or 6, wherein the loading rate of a loading test is 0.02-0.05 mm/min; the test times of the roof anchor rod tray and the roof anchor cable tray are not less than 3 times respectively, and the test times of the roof steel belt are not less than 5 times; the test times of the side anchor rod tray and the side anchor cable tray are respectively not less than 6 times, and the test times of the side steel belt are not less than 10 times.

8. The method for accurately calculating the shock resistance of the coal mine tunnel according to claim 1, wherein a cage type purse seine impact tester is adopted to perform impact tests on the surface protection nets used on site, and the energy absorbed by the top plate and the side surface protection nets is respectively obtained as E_dw、E_bwThe method comprises the following specific steps:

firstly, materials are taken, and surface protecting nets are respectively taken down from a top plate and an upper part of a rock burst roadway supporting site to serve as test materials;

performing a cage type purse seine impact test on the test material obtained in the step one by using a cage type football purse seine impact tester to obtain the maximum load borne by the watch seine along with the change of displacement, obtaining a stress-strain curve of the watch seine, and calculating the absorption work index of the watch seine in the impact process;

and thirdly, energy calculation, namely integrating the stress-strain curves according to the obtained stress-strain curves of the top plate meter protecting net and the side part meter protecting net, and calculating the area enclosed by the stress-strain curves and the coordinate axes, namely the energy which can be absorbed. Averaging the test results, and respectively recording the energy absorbed by the top plate and the upper part protective surface net as E_dw、E_bw。

9. The method for accurately calculating the impact resistance of the coal mine tunnel according to claim 8, wherein not less than 3 and 4m roof plates are taken down from a rock burst tunnel support site²The surface protecting net is used as a top plate test material, and at least 6 pieces of 4m are taken down from the upper part²The upper protective net was used as a test material for the upper.

10. The method for accurately calculating the impact resistance of the coal mine tunnel according to claim 8 or 9, wherein the top plate surface protection net is subjected to not less than 3 tests, and the side surface protection net is subjected to not less than 6 tests.

Technical Field

The invention relates to a method for accurately calculating the impact resistance of a coal mine tunnel.

Background

In recent years, rock burst accidents in coal mine tunnels frequently occur, and very disastrous casualties and property loss are caused. Reasonable supporting and pressure relief measures are prevention and control measures which must be taken by the rock burst roadway, and accurate calculation of the impact resistance of the roadway has important significance for prediction and prevention and control of rock burst. At present, the calculation method of the impact resistance is still few, and only ' a calculation method of the impact resistance of a roadway roof anchoring support ' (application publication No. CN 111259542A) ' is provided. Wang Aiwen et al

In the text of the strength calculation method for the three-stage energy-absorbing support of the coal mine rock burst roadway, an impact resistance calculation method for forming the three-stage energy-absorbing support by using an energy-absorbing anchor rod, a flexible O-shaped shed and an energy-absorbing hydraulic support is mentioned, but the energy-absorbing impact-resisting energy of the method is calculated only through simple accumulation and lacks certain rationality; wu Yu Zheng in the theory of ' pressure relief-support-protection ' cooperative prevention and control principle and technology of deep rock burst roadway ' for calculating the impact resistance, the single impact resistance of the anchor rod, the anchor cable, the metal net, the U-shaped shed and the hydraulic support is accumulated to obtain the impact resistance of the support system, but the important influence of pressure relief, steel belt and tray on impact resistance is ignored, and the impact resistance contribution rate of a top plate, a side part and pressure relief measures is not distinguished, so that the obtained result is greatly different from the actual result.

In fact, the roadway impact resistance is that of the support system anchor; anchor cables, auxiliary system trays, steel belts and meter protecting nets; the macroscopic embodiment of combined action of a hydraulic support with advanced support measures, a pressure relief hole with pressure relief measures and the like. In general, the existing impact resistance calculation method has the following defects:

(1) in the existing impact resistance calculation methods, the impact resistance energy of support members, mainly anchor rods and anchor cables, is simply accumulated. In the calculation method, the impact resistance energy of each supporting member is an empirical value retrieved according to documents, and the empirical value is obtained by measuring and calculating the supporting member under the action of quasi-static load; on one hand, the impact resistance of the lower supporting member under the action of dynamic load impact is not fully considered, and on the other hand, along with the improvement of the processing material of the supporting structure and the improvement of the mechanical property of the supporting structure, the empirical value cannot reflect the impact resistance of the lower anchor cable supporting material.

(2) The support factors are not considered comprehensively. The existing impact resistance calculation method only considers the impact resistance of anchor rods and anchor cables, does not consider the impact resistance of supporting and matching parts such as trays, steel belts, surface protecting nets and the like, and neglects the energy absorbed by advanced supporting measures and the self deformation of surrounding rocks.

(3) For a rock burst roadway, pressure relief of a large-diameter drill hole becomes a necessary measure, the large-diameter drill hole absorbs energy through shrinkage deformation so as to improve the impact resistance of a support system, and the measure is a factor which must be considered in the calculation process of the impact resistance of the roadway, but the energy which can be absorbed by a pressure relief hole is not calculated in the existing impact resistance calculation methods.

Disclosure of Invention

Aiming at various defects of the existing impact resistance calculation method, the invention provides a coal mine roadway impact resistance accurate calculation method, and roadway impact resistance calculation is carried out by a more accurate and reasonable method.

The technical scheme is as follows: a method for accurately calculating the impact resistance of a coal mine tunnel comprises the following steps:

the first step is as follows: investigating and researching on-site engineering geological conditions and concrete roadway support parameters

Firstly, surveying and determining support parameters of a site roadway, and specifically comprises the following steps: number n of roof single row anchor rods_dg(ii) a Number n of roof single-row anchor cables_ds(ii) a The row pitch c of roof bolt support; the width a of the roadway; number n of side single-row anchor rods_bg(ii) a Number n of side single-row anchor cables_bs(ii) a The row spacing d of anchor rod support of the upper part; the height b of the roadway;

secondly, investigating and determining pressure relief parameters of the site roadway, and specifically comprises the following steps: area S of pressure relief hole_kDepth h of relief hole_kD, the diameter of the pressure relief holes and the distance l between the pressure relief holes;

and thirdly, investigating and determining engineering geological parameters of the site roadway, which specifically comprises the following steps: vertical stress sigma of the roadway_hThe volume weight gamma of surrounding rocks of the roadway, the burial depth h of the roadway, the periodic pressure step distance L of the roadway and the overall stability of the roadway;

fourthly, researching parameters of advanced support measures, which specifically comprises the following steps: the number n of the forepoling frames within the range of the step pitch of one period of incoming pressure_zThe rigidity K of the hydraulic support, the effective supporting area S of the support group and the displacement W of the hydraulic support.

The second step is that: impact member energy determination

The anti-impact and supporting members used on site are taken, a dynamic impact experiment is carried out, the energy which can be absorbed by each supporting member is measured, and practical and reliable basic data are provided for calculating the energy which can be absorbed by the whole supporting structure in the next step.

Step I: dynamic load impact test is carried out on anchor rods and anchor cables used in supporting field

The method comprises the following specific steps:

firstly, materials are taken, and sampling is respectively carried out on a top plate anchor rod, a top plate anchor cable, an upper part anchor rod and an upper part anchor cable on a rock burst roadway support site, wherein the sampling quantity of the top plate anchor rod and the top plate anchor cable is not less than 5, the sampling quantity of the upper part anchor rod and the upper part anchor cable is not less than 10, and the sampling length of a single sample is 50 mm;

secondly, performing a test, namely performing a dynamic load impact test on the sample obtained in the first step by using a Charpy test device, determining an impact absorption work index of a supporting material, breaking the sample by one-time impact of a pendulum bob, collecting and recording a force-displacement curve, performing the test by using a V-shaped notch, wherein the curvature radius of the root of the notch is 0.25mm, the depth of the notch is 2mm, and the notch angle is 45 degrees, performing the detailed test step according to a GB2106 metal Charpy (V-shaped notch) impact test determination method, performing multiple tests on a roof anchor rod, a roof anchor cable, an upper anchor rod and an upper anchor cable, wherein the test times of the roof anchor rod and the roof anchor cable are respectively not less than 5 times, and the test times of the upper anchor rod and the upper anchor cable are respectively not less than 10 times;

calculating energy, namely the area enclosed by the force-displacement curve and the coordinate axis is the total energy of impact absorption, averaging the test results for many times, and respectively recording the average energy absorbed by the roof anchor rod, the roof anchor cable, the side anchor rod and the side anchor cable as follows: e_{D rod}、E_{D cable}、E_{b rod}、E_{b cable}。

Step II: a power machine is adopted to carry out a power loading test on a tray and a steel belt, and the method comprises the following specific steps:

firstly, materials are taken, and a top plate anchor rod tray, a top plate anchor cable tray, a side part anchor rod tray, a top plate steel belt and a side part steel belt which are used in a rock burst roadway site are respectively sampled, wherein the sampling number of the top plate anchor rod tray and the top plate anchor cable tray is not less than 3, the sampling total length of the top plate steel belt is not less than 200mm, and the sampling number is not less than 5; the sampling number of the upper anchor rod tray and the upper anchor cable tray is not less than 6 respectively, the total sampling length of the upper steel belt is not less than 400mm, and the sampling number is not less than 10;

secondly, performing a loading test on the plurality of samples obtained in the first step by adopting an electro-hydraulic servo hydraulic universal testing machine JL-WAW 60, wherein the loading rate is 0.02-0.05 mm/min, and analyzing the change rule of mechanical characteristics in the loading process to respectively obtain the maximum bearing capacity and deformation height indexes of a top plate anchor rod tray, a top plate steel belt, a side part anchor rod tray and a side part steel belt, so as to obtain stress-strain curves of the top plate anchor rod tray and the top plate anchor rod tray, wherein the test times of the top plate anchor rod tray and the top plate anchor rod tray are not less than 3 times respectively, and the test times of the top plate steel belt are not less than 5 times; the test times of the side anchor rod tray and the side anchor cable tray are respectively not less than 6 times, and the test times of the side steel belt are not less than 10 times;

calculating energy, respectively calculating the area enclosed by the stress-strain curves corresponding to the supporting materials and coordinate axes according to the stress-strain curves obtained in the second step, namely the absorbed energy value, carrying out averaging processing on the test results for a plurality of times, and respectively recording the energy absorbed by the roof anchor rod tray, the roof anchor cable tray, the roof steel belt, the side anchor rod tray, the side anchor cable tray and the side steel belt as follows: e_{D pole holder}、E_{D cable support}、E_{d steel band}、E_{b pole holder}、E_{b cable support}、E_{b steel band}；

Step III: impact test of watch protecting net

Adopting a cage type purse net impact tester to carry out impact test on a graticule or an engineering plastic net used on site to obtain the energy which can be absorbed by a surface protection net, and the method comprises the following specific steps:

firstly, materials are taken, and not less than 3 and 4m roof plates are taken down from a rock burst roadway support site²The surface protecting net is used as a top plate test material, and at least 6 pieces of 4m are taken down from the upper part²The surface protecting net is used as a test material of the upper part;

performing a cage type purse seine impact test on the test material obtained in the step one by using a cage type football purse seine impact testing machine to obtain the maximum load which can be borne by the guard purse seine along with the change of displacement, obtaining a stress-strain curve of the guard purse seine, calculating the absorption work index of the guard purse seine in the impact process, respectively performing not less than 3 tests on the top plate guard purse seine, and performing not less than 6 tests on the side guard purse seine;

thirdly, energy calculation, namely, according to the obtained stress-strain curves of the top plate meter protecting net and the upper part meter protecting net, integrating the stress-strain curves to obtain the area enclosed by the stress-strain curves and coordinate axes, namely the energy which can be absorbed, averaging the multiple test results, and respectively calculating the energy which can be absorbed by the top plate meter protecting net and the upper part meter protecting net as E_dw、E_bw；

The third step: calculating the energy that a roadway support structure of unit area can absorb

Step I: the energy of the top plate is calculated according to the following formula:

E_d＝[n_dg×(E_{d rod}+E_{D pole holder})+n_ds×(E_{D cable}+E_{D cable support})+E_{d steel band}]/(a×c)+E_dw (1)

In the formula: e_dIs the energy that the supporting structure of the roadway roof in unit area can absorb; n is_dgThe number of the roof single-row anchor rods; e_{D rod}The energy which can be absorbed by a single anchor rod of the top plate; e_{D pole holder}The energy absorbed by the tray matched with the roof bolt; n is_dsThe number of the single-row anchor cables of the top plate; e_{D cable}The energy absorbed by a single anchor cable on the top plate; e_{D cable support}The energy absorbed by the tray matched with the top plate anchor cable; e_{d steel band}The energy that the steel strip of the top plate can absorb; a is the width of the roadway; c is the roof bolting row spacing; e_dwIs the energy that the surface protecting net of the unit area of the top plate can absorb.

Step II: the energy of the upper part is calculated according to the following formula:

E_b＝[n_bg×(E_{b rod}+E_{b pole holder})+n_bs×(E_{b cable}+E_{b cable support})+E_{b steel band}]/(b×d)+E_bw (2)

In the formula: e_bIs the energy that the supporting structure of the roadway side part in unit area can absorb; n is_bgThe number of the single-row anchor rods on the upper part; e_{b rod}The energy which can be absorbed by a single anchor rod on the upper part; e_{b pole holder}The energy absorbed by the tray matched with the upper anchor rod; n is_bsThe number of the single-row anchor cables on the upper part is set; e_{b cable}Energy which can be absorbed by a single anchor cable at the upper part; e_{b cable support}The tray matched with the anchor cable at the upper part can absorb energy; e_{b steel band}The energy which can be absorbed by the upper steel belt; b is the height of the roadway; d is the row spacing of the anchor rod support of the upper part; e_bwIs the energy which can be absorbed by the surface protecting net of the unit area of the upper part.

Step III: calculating the energy absorbed by the pressure relief hole in the roadway

The energy that can be absorbed by the pressure relief borehole is calculated according to the following equation:

E_k＝S_k×k_b×h_k×σ_h/(l×b) (3)

σ_h＝γh (5)

in the formula: e_kEnergy, S, absorbed per unit area of pressure relief borehole_kArea of pressure relief holes, h_kDepth of relief hole, k_bThe closing coefficient of the pressure relief hole is 0.1-0.2 percent, sigma_hThe vertical stress at the drill hole is represented by pi being 3.14 in circumferential ratio and gamma being 25-27 kN/m in volume weight³H is the buried depth of the roadway, d is the diameter of the pressure relief holes, b is the height of the roadway, and l is the distance between the pressure relief holes.

Step IV: energy calculation for hydraulic supports and other advance support measures

The energy that can be absorbed by the hydraulic mount is calculated according to the following formula:

in the formula: e_yAverage energy that a unit area of the hydraulic support can absorb, n_zThe number of the forepoling in the step pitch of one period of pressure coming is taken as K is the rigidity of the hydraulic bracket, and 0.14 multiplied by 10 is taken as⁸(N/m²) S is the effective supporting area of the bracket group, and 0.7-0.8 of the contact area of the bracket is taken; w is the displacement of the hydraulic support; a is the width of the roadway; and L is the periodic pressure step distance of the roadway.

The fourth step: comprehensive calculation of tunnel impact resistance

Step I: determining a weight coefficient

Determining the energy E which can be absorbed by the top plate supporting structure in unit area according to the stability condition of the surrounding rock of the roadway_dEnergy absorbed by unit area roadway wall structureQuantity E_b(ii) a Energy E absorbed by unit area of upper pressure relief drilling_kThe weights of the three components are shown in Table 1, wherein α is E_dOccupied weight, beta is E_bThe occupied weight, gamma is E_kThe weight occupied.

Table 1 weight impact factor distribution table

Stability condition of surrounding rock of roadway	α	β	γ
				Is very stable	0.4	0.4	0.2
Stabilization	0.5	0.3	0.2
				Moderate stability	0.6	0.3	0.1
Instability of the film	0.7	0.2	0.1

Step II: weight assignment calculation

The weight factors alpha, beta and gamma are combined into a matrix A

Energy E absorbed by a unit area top plate supporting structure_dEnergy E absorbed by unit area roadway wall structure_b(ii) a Energy E absorbed by unit area of upper pressure relief drilling_kThe matrix B is formed by combining the two matrixes,

step III: calculating the impact resistance of the unit area of the roadway after the weight distribution

In the formula, E_zThe impact resistance of the unit area of the roadway after the weight is distributed.

Step IV: calculating comprehensive impact resistance of tunnel

According to the first step of investigating the roof conditions of the roadway, calculating the periodic pressure step L of the roadway, taking the length range of the periodic pressure step as a whole, and calculating the comprehensive impact resistance of the roadway according to the following formula:

E_L＝[(a+2b)×E_z+a×E_y]×L (9)

in the formula, E_LThe comprehensive impact resistance of the roadway taking the periodic pressure step as the length is realized; a is the width of the roadway, and b is the height of the roadway; e_zThe impact resistance of the unit area of the roadway after the weight is distributed; e_yThe average energy which can be absorbed by the unit area of the hydraulic support; l is the periodic pressure step under the condition of the top plate.

Has the advantages that:

(1) according to the calculation method, details such as material taking, experimental equipment, loading modes and the like in an experiment are determined by carrying out dynamic load impact test on the material taking of each supporting component on site, a real impact energy resistance value can be obtained, weight distribution is carried out on the energy which can be absorbed by each supporting component and the pressure relief holes of the top plate and the upper part according to the stability condition of the surrounding rock, the source of basic data is real and effective, the energy calculation method is scientific and reasonable, and the accurate and systematic calculation method of the impact resistance is formed.

(2) The method has the advantages that the existing impact resistance calculation methods do not consider the effect of pressure relief measures, the invention provides a specific calculation formula of energy absorption of the pressure relief holes, the impact resistance energy of the pressure relief measures is comprehensively weighted and calculated according to the surrounding rock conditions, and the influence relationship of the pressure relief measures on the impact resistance of the roadway is comprehensively considered.

(3) The effect of the supporting member is fully considered. The existing impact resistance calculation method only considers the energy calculation of partial impact-resistant support members such as anchor rods, anchor cables and the like, but the method comprehensively and fully considers the impact resistance of each support structure of a top plate and a side part including the anchor rods, the anchor cables, a tray, a steel belt and a surface protecting net, and fully considers the energy absorbed by advanced support measures, so that the calculation result is more consistent with the actual situation on site.

Detailed Description

The patent is further illustrated below with reference to specific examples:

and (3) taking a certain mine as a rock burst dangerous mine, and carrying out strong support and large-diameter drilling treatment on a roadway with impact danger. Now, according to the calculation method of the present invention, the impact resistance is calculated.

The first step is as follows: and (5) investigating relevant design parameters.

Firstly, specific support parameters of a site roadway are investigated and determined: number n of roof single row anchor rods_dg7 in number; number n of roof single-row anchor cables_ds2 in number; the row spacing c of roof bolt supports is 0.95 m; the width a of the roadway is 5.2 m; number n of side single-row anchor rods_bg5 are; single-row anchor for upper partNumber n of cables_bs2 in number; the row spacing d of the anchor rod support of the upper part is 0.90 m; the height b of the roadway is 3.7 m;

secondly, specific pressure relief parameters of the site roadway are investigated and determined: depth h of pressure relief hole_k20m, the diameter d of the pressure relief holes is 150mm, and the distance l between the pressure relief holes is 2.0 m.

And thirdly, investigating and determining concrete engineering geological parameters of the site roadway, which specifically comprises the following steps: the volume weight gamma of the surrounding rock of the roadway is 25kN/m³The depth h of the roadway is 750m, the periodic pressure step L of the roadway is 40m, and the overall stability condition of the roadway belongs to a stable roadway.

Fourthly, specific parameters of advanced support measures are investigated: the number n of the forepoling frames within the range of the step pitch of one period of incoming pressure_z20 groups, the rigidity K of the hydraulic bracket is 0.14 multiplied by 10⁸(N/m²) The effective supporting area S of the support group is 4.8m, and the displacement W of the hydraulic support is 300 mm.

The second step is that: impact member energy measurement.

Step I: and carrying out dynamic load impact test on the anchor rods and the anchor cables used in the supporting field.

Firstly, the materials are obtained. Respectively taking 5 samples from a roof anchor rod and a roof anchor cable on a rock burst roadway support site, then taking 10 samples from the anchor rod of the side part, wherein the sampling number of the anchor cables of the side part is also 10, and the sampling lengths of all the samples are ensured to be 50 mm. ② testing. And (4) testing the sample obtained in the first step by using a Charpy testing device. And thirdly, energy calculation. Integrating the test curve to obtain 5 times of test energy of the roof bolt, and averaging to finally determine the energy E absorbed by the roof bolt_{D rod}3.5 kJ/root; energy E absorbed by roof anchor cable_{D cable}Energy E absorbed by 8.2 kJ/root and upper anchor rod_{b rod}Energy E absorbed by 3.1 kJ/anchor cable at the root and side part_{b cable}It was 7.8 kJ/root.

Step II: a power machine is adopted to carry out a power loading test on the tray and the steel belt.

Firstly, the materials are obtained. Taking 3 roof anchor rod trays, 3 roof anchor cable trays, 6 side anchor rod trays, 6 side anchor cable trays and roof steel strips from a rock burst roadway on site to obtain the total length200mm samples were 5, and 10 samples with a total length of 400mm were taken. ② testing. And (4) carrying out a loading test on the plurality of samples obtained in the first step. And thirdly, energy calculation. Averaging the multiple test results to obtain the energy E absorbed by the roof anchor tray_{D pole holder}Energy E which can be absorbed by 2.7 kJ/anchor cable tray of top plate_{D cable support}Energy E absorbed by 6.3 kJ/top plate steel strip_{d steel band}Energy E absorbed by the anchor rod tray of 4.6 kJ/bar and upper part_{b pole holder}Energy E which can be absorbed by the anchor cable tray with the upper part of 2.5 kJ/anchor cable tray_{b cable support}5.9 kJ/piece of energy E which can be absorbed by the upper steel strip_{b steel band}It was 4.7 kJ/bar.

Step III: and (5) impact test of the surface protection net.

Firstly, the materials are obtained. Taking off 3 roof plates 4m from rock burst roadway support site²The watch protecting net is taken down 6 pieces 4m from the upper part²The upper protective net was used as a test material for the upper. And secondly, protecting the surface net for impact test. And (4) carrying out a cage type purse net impact experiment on the test material obtained in the first step. And thirdly, calculating energy and processing results. Integrating the obtained stress-strain curves of the top plate protecting surface net and the side protecting surface net, respectively carrying out averaging processing on the multiple test results of the top plate protecting surface net and the side protecting surface net, and obtaining the energy E which can be absorbed by the top plate protecting surface net_dwIs 0.53kJ/m²Energy E absorbed by upper part watch protecting net_bwIs 0.54kJ/m²。

The third step: and calculating the energy which can be absorbed by the roadway supporting structure in unit area.

Step I: the energy of the top plate is calculated according to equation (1):

E_d＝[n_dg×(E_{d rod}+E_{D pole holder})+n_ds×(E_{D cable}+E_{D cable support})+E_{d steel band}]/(a×c)+E_dw (1)

According to the dynamic load test result of the mine, the related energy value is brought in, and the energy E which can be absorbed by the roof supporting structure in unit area can be obtained_dComprises the following steps:

E_d＝[7×(3.5+2.7)+2×(8.2+6.3)+4.6]/(5.2×0.95)+0.53＝16.12kJ/m²

step II: the energy of the upper is calculated according to the formula (2):

E_b＝[n_bg×(E_{b rod}+E_{b pole holder})+n_bs×(E_{b cable}+E_{b cable support})+E_{b steel band}]/(b×d)+E_bw (2)

According to the dynamic load test result of the mine, related energy parameters are introduced, and the energy E which can be absorbed by the upper supporting structure in unit area can be obtained_bComprises the following steps:

E_b＝[5×(3.1+2.5)+2×(7.8+5.9)+4.7]/(3.7×0.90)+0.54＝18.59kJ/m²

step III: the energy that can be absorbed by the pressure relief vent taken at the site is calculated.

According to the first step of investigation result, the buried depth h of the roadway is 750 m; the volume weight gamma is 25kN/m³(ii) a The circumferential rate pi is 3.14; the diameter d of the pressure relief hole is 0.15 m; coefficient of closure k_bTaking 0.2%; depth h of pressure relief hole_kIs 20 m; the hole pitch was 2.0 m; the roadway height is 3.7 m. The energy absorbed by the pressure relief borehole per unit area is then, according to equations (3) to (5):

σ_h＝25×750＝18.75MPa

E_k＝0.035325×20×0.2％×18.75÷(2.0×3.7)＝3.58kJ/m²

step IV: and (4) calculating advance support measures such as a hydraulic support and the like.

According to the formula (6), the energy that can be absorbed by the hydraulic support is calculated:

the fourth step: and comprehensively calculating the impact resistance of the tunnel.

According to the energy calculation formula in the third step, determining the energy E which can be absorbed by the roof supporting structure_dIs 16.12kJ/m²Energy E absorbed by the tunnel wall structure_bIs 18.59kJ/m²(ii) a Energy E absorbed by pressure relief drilling_kIs 3.58kJ/m²。

Step I: a weight coefficient is determined. According to the fact that the roadway surrounding rock belongs to the stable type, the weighting influence factor distribution table 1 is consulted, and the weighting coefficients alpha, beta and gamma are determined to be 0.5, 0.3 and 0.2 respectively.

Step II: and calculating weight distribution.

The weight factors alpha, beta and gamma are combined into a matrix A

Energy E absorbed by supporting structure in unit area_d，E_b，E_kConstituting a matrix B.

Step III: and calculating the impact resistance of the unit area of the roadway after the weight is distributed. Substituting the weighting factor and the energy parameter into equation (8) yields:

step IV: and calculating the comprehensive impact resistance of the roadway.

According to the first step of investigation, if the periodic step length L is 40m, the length range of the periodic step length is taken as a whole. The comprehensive impact resistance of the roadway is calculated according to the formula (9):

E_L＝[(5.2+2×3.7)×14.353+5.2×8.07]×40＝8.914×10⁶J

therefore, the impact resistance of the coal mine tunnel is as follows: can resist 8.914 x 10⁶Impact energy of J.