Method for measuring lateral bearing pressure distribution of working face based on anchor cable support

Abstract

The invention discloses a method for measuring the lateral bearing pressure distribution of a working face based on anchor cable support. The method comprises the following steps: determining the mounting depth of an anchor cable; the method comprises the following steps: manufacturing a bearing pressure test type anchor cable, namely fixedly mounting a plurality of force measuring devices at equal intervals along the length direction of the anchor cable, each force measuring device comprises a rigging and a stress sensor, the stress sensors are fixedly mounted on the top end plane of the rigging, and all the stress sensors are along the length direction of the anchor cable. Monitoring and recording the data change of the stress sensor in real time, and determining the influence range and peak position of the lateral bearing pressure of the working face. By arranging the stress sensors at multiple points, the bearing pressure value of the lateral coal wall of the mining roadway in the anchoring direction can be measured, so that a lateral bearing pressure distribution diagram is obtained, and the bearing pressure peak point and the bearing pressure influence area range are summarized; therefore, pressure relief and reinforced support are carried out on the mining roadway with the impact danger according to the lateral bearing pressure distribution condition.

Description

Technical Field

[0001] The invention relates to the field of coal mine working face support pressure testing, in particular to a method for measuring lateral support pressure distribution of a working face based on anchor cable support. Background Art

[0002] After coal mining, stress redistribution will inevitably occur in the surrounding rock of the tunnel or mining area. Within the range of surrounding rock stress redistribution, the vertical stress acting on the coal seam, rock layer and gangue is called support pressure. Due to the complex and changeable geological structure and lithology of coal mines in my country, and the gradual increase in the depth and intensity of coal seam mining in recent years, the distribution of lateral support pressure after coal mining has become more and more complicated, which brings great difficulties to the selection of the location and time of mining tunnel excavation; at the same time, for mining tunnels with impact hazards, it is necessary to carry out pressure relief and strengthen support according to the distribution of lateral support pressure. Therefore, accurately obtaining the distribution law of lateral support pressure of the working face is of great significance for mining tunnel construction and surrounding rock control.

[0003] Chinese patent 202020689270.9 proposes a safety monitoring system for lateral coal support pressure in goaf areas. Drill holes of different depths and install stress collectors in the holes. The stress monitoring system can accurately measure the lateral support pressure distribution in the coal body. The disadvantage is that the coal body needs to be drilled multiple times during the measurement process, and the higher the measurement accuracy requirement, the more holes need to be arranged, which not only destroys the inherent force characteristics of the coal body itself, but also increases the construction difficulty and workload of the project.

[0004] There is also an audio monitoring method for coal wall support force in the prior art (patent number 201310527857.4), which also requires drilling holes of different depths, injecting liquid into the holes to rupture the inner wall of the long holes, and the audio sensor receives the signal of increased audio when the hole wall ruptures. At this time, the value of the injection pressure recorded is the value of the coal wall support pressure. This method can measure the support pressure through multi-point measurement, but the injection process may cause leakage of hydraulic oil, and damage to the pipe wall will also affect the use of the device. Multiple drillings destroy the inherent force characteristics of the coal body itself, increasing the construction volume and difficulty of the project. Summary of the invention

[0005] In order to accurately obtain the distribution of lateral support pressure of mining working face and provide a basis for excavation and support design of mining tunnels under similar conditions, the present invention provides a method for measuring the distribution of lateral support pressure of working face based on anchor cable support, which is easy to operate, has high measurement accuracy and a wide range of applications.

[0006] In order to achieve the above object, the technical solution of the present invention is as follows: A method for measuring the lateral support pressure distribution of a working face based on anchor cable support, comprising the following steps:

[0007] S100: Determine the installation depth L of the anchor cable;

[0008] S200: manufacturing a bearing pressure test type anchor cable, including: fixing and installing a plurality of force measuring devices at equal intervals along the length direction of the anchor cable, the force measuring devices including rigging and stress sensors; the stress sensors are fixedly installed on the top plane of the rigging, all the stress sensors are along the length direction of the anchor cable, and the connection lines of the stress sensors are consistent with the length direction of the anchor cable;

[0009] S300: Installation of new bearing pressure test anchor cable;

[0010] S400: monitor and record stress sensor data changes in real time;

[0011] S500: Determine the influence range and peak position of the lateral support pressure of the working face.

[0012] Further, determining the installation depth L of the anchor cable in S100 includes:

[0013] S1001: Estimate the distance x0 between the peak point of the support pressure and the coal seam:

[0014]

[0015] In formula 1: K is the stress concentration factor (value ranges from 2 to 4); N0 is the support force of the coal wall in the plastic zone, and

[0016] τ0—shear stress; λ—lateral pressure coefficient, and f—friction factor between layers; —internal friction angle of roof coal;

[0017] m—coal seam thickness; γ—average bulk density of overlying rock formations; H—burial depth;

[0018] S1002: Calculate the distance x1 between the bearing pressure influence range and the coal seam:

[0019]

[0020] In formula 2: β—lateral pressure coefficient;

[0021] The installation length L of the anchor cable is:

[0022] L = n·x1 Formula 3;

[0023] In formula 3: n is the reserve coefficient, which can be any number between 1 and 1.5.

[0024] Furthermore, the installation of a new type of supporting pressure test anchor cable in S300 includes:

[0025] S3001: Select a location without obvious geological structure in the mining roadway, drill an anchor cable borehole in the non-mined coal side of the mining roadway, arrange the borehole along the coal seam, perpendicular to the direction of the roadway, and the borehole depth is L;

[0026] S3002: Install the new type of bearing pressure test anchor cable in the borehole, ensure that the stress sensor faces upward to accurately test the vertical pressure, and organize the stress sensor measurement line, connect it to the test base station, and transmit it to the ground computer system;

[0027] S3003: Grout the borehole to fill the gap between the sensor and the surrounding rock to ensure that the surrounding rock pressure is transmitted to the sensor.

[0028] Furthermore, the determination of the influence range and peak position of the lateral support pressure of the working surface in S500 includes:

[0029] S5001: Analyze the monitoring data, take the distance between the stress sensor and the coal seam as the x-axis and the corresponding stress value as the y-axis, and draw the lateral support pressure curve when the working face advances at different distances;

[0030] S5002: Analyze the above lateral support pressure curves. The x-coordinate value of the peak value of each curve is the distance of the lateral support pressure peak value from the coal seam when the working face is advanced. The pressure increase range in the curve is the influence range of the lateral support pressure when the working face is advanced.

[0031] Compared with the prior art, the present invention designs a method for measuring the lateral support pressure distribution of the working face based on anchor cable support. By setting stress sensors at multiple points, the support pressure value of the lateral coal wall of the mining roadway along the anchoring direction can be measured, thereby obtaining a lateral support pressure distribution diagram, summarizing the support pressure peak point and the support pressure influence area range, and thus carrying out pressure relief and strengthening support for the mining roadway with impact danger according to the lateral support pressure distribution. The invention avoids the operation of multiple drillings on the lateral coal body of the roadway, and avoids the influence of multiple drillings on the stress condition of the lateral coal body, including stress concentration and coal body damage during drilling, and can better and more accurately measure the distribution of the lateral support pressure of the coal body in the roadway. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a cross-sectional view in the positive direction of the anchor cable structure;

[0033] Figure 2 It is a side cross-sectional view of the construction process of the example of the present invention;

[0034] Figure 3 It is a side section view of a single rigging and anchor cable structure;

[0035] Figure 4 This is a single peak test stress diagram.

[0036] In the figure: 1-anchor cable, 2-stress sensor, 3-rigging, 4-test line; 5-test base station, 6-anchor cable drilling hole. DETAILED DESCRIPTION

[0037] In order to facilitate those skilled in the art to understand the technical solution of the present invention, further description will be given below with reference to the accompanying drawings. It should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present invention.

[0038] In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of embodiments of the present invention. However, it is apparent that one or more embodiments may be implemented without these specific details. In addition, in the following description, descriptions of known structures and techniques are omitted to avoid unnecessary confusion of concepts of the present invention.

[0039] refer to Figure 1-4 The present invention describes a method for measuring the lateral bearing pressure distribution of a working face based on anchor cable support, which includes the following steps:

[0040] S100: Determine the installation depth L of the anchor cable 1. In specific implementation, the following steps are included:

[0041] S1001 estimates the distance x0 between the peak point of the support pressure and the coal seam:

[0042]

[0043] In formula 1: K is stress concentration factor (value ranges from 2 to 4); N0 is the support force of the coal wall in the plastic zone, and N0 = τ0cotφ;

[0044] τ0—shear stress; λ—lateral pressure coefficient, and f—friction factor between layers; φ—internal friction angle of roof coal;

[0045] m—coal seam thickness; γ—average bulk density of overlying rock formations; H—burial depth;

[0046] S1002: Calculate the distance x1 between the bearing pressure influence range and the coal seam:

[0047]

[0048] Where: β—lateral pressure coefficient;

[0049] The installation length L of the anchor cable is:

[0050] L = n·x1 Formula 3;

[0051] In formula 3: n is the reserve coefficient, which can generally be 1 to 1.5.

[0052] S200: Make a new type of bearing pressure test anchor cable, see Figure 1 ;

[0053] The rigging 3 is installed on the anchor cable 1 at equal intervals. The top of the rigging 3 is made into a plane. The stress sensor 2 is welded to the top plane of the rigging 3. The measuring line housing of the stress sensor 2 is made of high-strength pressure-resistant material to prevent it from being broken when the hole collapses.

[0054] S300: Install new type of bearing pressure test anchor cable, see Figure 2 and Figure 3 ;

[0055] S3001: Select a location without obvious geological structure in the mining roadway, drill an anchor cable borehole 6 in the non-mined coal side of the mining roadway, and arrange the borehole along the coal seam, perpendicular to the direction of the roadway, and the borehole depth is L;

[0056] S3002: Connect the test line 4 to the stress sensor 2, then install the new type of support test anchor cable inside the anchor cable borehole 6, ensure that the stress sensor 2 faces upward to ensure accurate testing of vertical pressure, and finally connect the test line 4 to the test base station 5, and transmit the signal to the ground computer system through the test base station 5;

[0057] S3003: Grouting is performed on the anchor cable borehole 6 to fill the gap between the stress sensor 2 and the surrounding rock to ensure that the surrounding rock pressure is transmitted to the stress sensor 2.

[0058] S400: Monitor and record stress sensor data changes in real time.

[0059] As the mining face advances, the values ​​of each stress sensor are monitored in real time and recorded and saved in the computer system.

[0060] S500: determining the influence range and peak position of the lateral support pressure of the working face;

[0061] S5001: Analyze the monitoring data, take the distance between the stress sensor and the coal seam as the x-axis and the corresponding stress value as the y-axis, and draw the lateral support pressure curve when the working face advances at different distances;

[0062] S5002: Analyze the above curves, see Figure 4 ;

[0063] Figure 4 Medium max is the peak value of the support pressure, x0 is the distance from the peak point to the coal wall, σ 末 is the support pressure value at the end of the support pressure influence zone, and x1 is the distance between the end of the support pressure influence zone and the coal wall.

[0064] In summary, the present invention designs a method for measuring the lateral support pressure distribution of the working face based on anchor cable support. By setting stress sensors at multiple points, the support pressure value of the lateral coal wall of the mining roadway along the anchoring direction can be measured, thereby obtaining a lateral support pressure distribution diagram, summarizing the support pressure peak point and the support pressure influence area range, and then carrying out pressure relief and strengthening support for the mining roadway with impact danger according to the lateral support pressure distribution. The invention avoids the operation of multiple drillings on the lateral coal body of the roadway, and avoids the influence of multiple drillings on the stress condition of the lateral coal body, including stress concentration and coal body damage during drilling, and can better and more accurately measure the distribution of the lateral support pressure of the coal body in the roadway.

[0065] The above embodiments are merely descriptions of preferred implementation modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for measuring the lateral support pressure distribution of a working face based on cable anchor support, characterized in that: The steps include: S100: Determine the installation depth L of the anchor cable; S200: manufacturing a bearing pressure test type anchor cable, including: fixing and installing a plurality of force measuring devices at equal intervals along the length direction of the anchor cable, the force measuring devices including rigging and stress sensors; the stress sensors are fixedly installed on the top plane of the rigging, all the stress sensors are along the length direction of the anchor cable, and the connection lines of the stress sensors are consistent with the length direction of the anchor cable; S300: Installation of new bearing pressure test anchor cable; S400: monitor and record stress sensor data changes in real time; S500: Determine the influence range and peak position of the lateral support pressure of the working face.

2. The method for measuring the lateral bearing pressure distribution of a working face based on cable anchor support according to claim 1 is characterized in that: Determining the installation depth L of the anchor cable in S100 includes: S1001: Estimate the distance x0 between the peak point of the support pressure and the coal seam: In formula 1: K is stress concentration factor (value ranges from 2 to 4); N0 is the support force of the coal wall in the plastic zone, and N0 = τ0cotφ; τ0—shear stress; λ—lateral pressure coefficient, and f—friction factor between layers; φ—internal friction angle of roof coal; m—coal seam thickness; γ—average bulk density of overlying rock strata; H—burial depth; S1002: Calculate the distance x1 between the bearing pressure influence range and the coal seam: In formula 2: β is the lateral pressure coefficient; then the installation length L of the anchor cable is: L = n·x1 Formula 3; In formula 3: n is the reserve coefficient, which can be any number between 1 and 1.

5.

3. The method for measuring the lateral bearing pressure distribution of a working face based on cable anchor support according to claim 2 is characterized in that: The S300 is equipped with a new type of bearing pressure test anchor cable, including: S3001: Select a location without obvious geological structure in the mining roadway, drill an anchor cable borehole in the non-mined coal side of the mining roadway, arrange the borehole along the coal seam, perpendicular to the direction of the roadway, and the borehole depth is L; S3002: Install the new type of bearing pressure test anchor cable in the borehole, ensure that the stress sensor faces upward to accurately test the vertical pressure, and arrange the measurement line of the stress sensor and connect it to the test base station 5 for transmission to the ground computer system; S3003: Grouting is performed on the borehole to fill the gap between the stress sensor and the surrounding rock to ensure that the surrounding rock pressure is transmitted to the stress sensor.

4. The method for measuring the lateral support pressure distribution of a working face based on cable anchor support according to claim 3 is characterized in that: Determining the influence range and peak position of the lateral support pressure of the working surface in S500 includes: S5001: Analyze the monitoring data, take the distance between the stress sensor and the coal seam as the x-axis and the corresponding stress value as the y-axis, and draw the lateral support pressure curve when the working face advances at different distances; S5002: Analyze the above lateral support pressure curves. The x-coordinate value of the peak value of each curve is the distance of the lateral support pressure peak value from the coal seam when the working face is advanced. The pressure increase range in the curve is the influence range of the lateral support pressure when the working face is advanced.

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