A method for distinguishing critical height of overburden rock and correcting support selection, which has influence on load of hydraulic support in working face

Abstract

The application provides a method for distinguishing critical height of overburden rock and correcting support selection, which has an influence on working face hydraulic support load. At present, the height of overburden rock which has an influence on working face hydraulic support load is mainly estimated by a theoretical calculation method, and there is still a lack of effective and accurate distinguishing method. The method is to compare and analyze the distributed optical cable breakpoint curve in the overburden rock with the working face hydraulic support load change curve, to determine the critical height of overburden rock which has an influence on working face hydraulic support load according to the corresponding relationship of the two curves, and to correct and calculate the maximum working resistance of the working face hydraulic support on the basis, so as to provide accurate basis for parameter determination of subsequent working face hydraulic support selection. Compared with other methods, the method is simple and reliable, and can provide important data support for working face strong mine pressure control.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of mine safety prevention and control, and particularly relates to a critical height of overburden rock influencing the load of a hydraulic support of a working face and a support selection correction method. BACKGROUND

[0002] According to a traditional correlation theory, the rock stratum influencing the load of the hydraulic support of the working face is mainly below the main roof, and therefore, when the hydraulic support of the working face is selected, the overburden rock load considered is limited to the range of the main roof. With the increasing of the mining depth and thickness of the coal seam, the influence range of the working face mining on the overburden rock is also increasing, and the overburden rock height influencing the working resistance of the hydraulic support of the working face is also increasing, and is not limited to the range below the main roof. Therefore, when the hydraulic support of the working face is selected, the overburden rock height influencing the working face after the coal seam is mined needs to be determined first, so that the overburden rock load influencing the working resistance of the hydraulic support can be calculated more accurately, thereby providing reliable data support for the selection of the hydraulic support.

[0003] The method for calculating the working resistance of the hydraulic support of the working face mainly includes a load estimation method, a measurement and statistics method and a theoretical analysis method, wherein the overburden rock height selected when the load of the hydraulic support of the working face is estimated in the load estimation method is 4-8 times the mining height, and the load of the hydraulic support of the working face obtained on this basis is not accurate enough; the measurement and statistics method needs a large amount of statistical values of the working face as a basis, and the calculation workload is large; and the theoretical analysis method has multiple assumption conditions or fuzzy parameters, and the above methods all have some disadvantages.

[0004] The present application is characterized in that the strain breakpoint curve of the distributed optical cable is compared and analyzed with the load curve of the hydraulic support of the working face, the critical height of the overburden rock influencing the load of the hydraulic support of the working face after the coal seam is mined is determined according to the corresponding relationship between the two types of curves, and the maximum working resistance of the hydraulic support of the working face is calculated and corrected on this basis. SUMMARY

[0005] In view of the deficiencies of the prior art, the present application aims to provide a critical height of overburden rock influencing the load of a hydraulic support of a working face and a support selection correction method.

[0006] In order to achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0007] A critical height of overburden rock influencing the load of a hydraulic support of a working face and a support selection correction method, comprising the following steps:

[0008] S1 involves setting up a surface borehole above the ground surface in the middle of the working face, with the borehole depth reaching the roof of the coal seam being mined.

[0009] After the S2 borehole construction was completed, distributed optical cables were laid from the borehole opening to the bottom of the borehole. After the distributed optical cables were laid to the bottom of the borehole, cement grout was used to seal the entire borehole to ensure that the distributed optical cable survey line was coupled with the surrounding rock of the borehole.

[0010] As the working face is mined and pushes past the borehole, the distributed optical cables inside the borehole will gradually break from bottom to top due to the mining activity.

[0011] S4 monitors the load on the hydraulic support below the borehole in real time and obtains the corresponding hydraulic support load change curve.

[0012] S5 determined the critical overburden height H that affects the load of the hydraulic support at the working face by comprehensively comparing the distribution optical cable breakpoint variation curves with the hydraulic support load variation curves. MAX m;

[0013] S6 obtains the maximum load p of the hydraulic support at the working face based on the determined critical height of the overburden. MAX校正 (Unit: kPa), thereby correcting and calculating the maximum working resistance P of the hydraulic support at the working face. MAX校正 (Unit: kN)

[0014] Furthermore, the specific process of step S1 in this invention is as follows:

[0015] During S1.1 drilling, core sampling should be performed on the bedrock section excluding the topsoil section. To facilitate subsequent mechanical testing, it is recommended that the core diameter be no less than 91mm.

[0016] S1.2 After full-hole coring, the thickness h of each rock layer inside the entire borehole was obtained. i m, the unit weight γ of each rock layer was obtained through mechanical testing. i (Unit: kN / m) 3 );

[0017] S1.3 To facilitate the subsequent deployment of distributed optical cables, the borehole is further enlarged after core sampling.

[0018] Furthermore, the specific process of step S2 in this invention is as follows:

[0019] After the S2.1 distributed optical cable is laid to the bottom of the hole, grouting and sealing are required. The cement grout used for sealing is mixed and stirred according to a certain water-cement ratio.

[0020] S2.2 In order to achieve the best coupling effect between the grout and the surrounding rock after solidification, the mechanical parameters of the solidified grout are first adjusted to be close to the mechanical parameters of each rock layer by adjusting different water-cement ratios. When sealing the borehole on site, different water-cement ratios are used for segmented grouting and sealing according to different rock layers.

[0021] Furthermore, the specific process of step S5 in this invention is as follows:

[0022] S5.1 By comprehensively comparing the distribution optical cable break point variation curve and the hydraulic support working resistance variation curve, multiple peak values ​​p of the hydraulic support load at the working face can be measured when a break occurs in the distribution optical cable at the bottom of the borehole. imax实测 However, as the working face continues to advance, the break points of the distributed optical cable will continue to rise, but the peak load of the hydraulic support at the working face will not continue to increase and will eventually remain at a maximum peak value p. MAX实测 ;

[0023] S5.2 Determine the first occurrence of p MAX实测 The height of the distributed optical cable break at that time is the critical overburden height H that affects the load on the hydraulic support of the working face. MAX ;

[0024] S5.3 In the comprehensive step S1.2, the critical overburden height H that affects the load on the hydraulic support of the working face is obtained. MAX The thicknesses of the rock layers within the following ranges are h1, h2, ..., h n With bulk density γ1, γ2, ..., γ n .

[0025] Furthermore, the specific process of step S6 in this invention is as follows:

[0026] S6.1 The critical overburden height H that affects the load on the hydraulic support of the working face, obtained from S5. MAX The maximum load of the hydraulic support at the working face is recalibrated and obtained using the following formula: p MAX校正 =∑h i γ i (i = 1, 2, ..., n);

[0027] S6.2 Further, the maximum working resistance of the corrected hydraulic support at the working face is obtained by the following calculation formula: P MAX校正 =(L k +L d Bp MAX校正 L k For the top distance, L d B is the length of the support top beam, and B is the support spacing. These three parameters are all fixed parameters (the unit is m).

[0028] S6.3 Furthermore, when selecting hydraulic supports for the working face in the subsequent process, it should be ensured that the maximum working resistance of all hydraulic supports is greater than P. MAX校正 .

[0029] The beneficial effects of this invention are as follows:

[0030] 1. The method of the present invention can accurately obtain the critical height of overburden that affects the load of the hydraulic support of the working face after coal seam mining, and then correct and calculate the maximum working resistance of the hydraulic support of the working face based on this height.

[0031] 2. The method of this invention is simple and can provide a reliable reference for the selection of hydraulic supports in working faces, thus providing important data support for the management of strong mining pressure in working faces. Attached Figure Description

[0032] Figure 1 This is a schematic diagram comparing the curve of the change in the distributed optical cable breakpoint inside the borehole with the curve of the change in the load of the hydraulic support at the working face in an embodiment of the present invention.

[0033] Figure 2 This is a schematic diagram of the drilling arrangement and segmented sealing in an embodiment of the present invention;

[0034] Figure 3 This is a schematic diagram of the critical overburden height that affects the hydraulic load on the working face in an embodiment of the present invention;

[0035] Figure 4 The length L of the top beam of the hydraulic support for the working face in this embodiment of the invention is... d Schematic diagram of bracket spacing B. Detailed Implementation

[0036] The present invention will be further described below with reference to the accompanying drawings. It should be noted that this embodiment is based on the present technical solution and provides detailed implementation methods and specific operation processes, but the protection scope of the present invention is not limited to this embodiment.

[0037] Example

[0038] like Figures 1 to 4 As shown, an embodiment of the present invention provides a method for determining the critical overburden height that affects the load on the hydraulic support of the working face and for correcting the support selection. The method includes the following steps:

[0039] S1 involves drilling a surface borehole above the ground surface in the middle of the working face, with the borehole reaching the roof of the coal seam.

[0040] During S1.1 drilling, core sampling should be performed on the bedrock section excluding the topsoil section. To facilitate subsequent mechanical testing, it is recommended that the core diameter be no less than 91mm.

[0041] S1.2 After full-hole coring, the thickness h of each rock layer inside the entire borehole was obtained. i m, the unit weight γ of each rock layer was obtained through mechanical testing. i (Unit: kN / m) 3 );

[0042] S1.3 To facilitate the subsequent deployment of distributed optical cables, the borehole is further enlarged after core sampling.

[0043] After the S2 borehole construction was completed, a distributed optical cable was laid from the borehole opening to the bottom. After the distributed optical cable was laid to the bottom of the borehole, the entire borehole was sealed with cement grout to ensure the coupling of the distributed optical cable survey line with the surrounding rock.

[0044] After the S2.1 distributed optical cable is laid to the bottom of the hole, grouting and sealing are required. The cement grout used for sealing is mixed and stirred according to a certain water-cement ratio.

[0045] S2.2 To achieve optimal coupling between the solidified grout and the surrounding rock, the mechanical parameters of the solidified grout were first adjusted to approximate the mechanical parameters of each rock stratum by varying the water-cement ratio. During on-site sealing, segmented grouting with different water-cement ratios was then performed according to different rock strata, achieving the desired effect. Figure 2 As shown.

[0046] As the working face is mined and pushes past the borehole, the distributed optical cables inside the borehole will gradually break from bottom to top due to the mining activity.

[0047] S4 monitors the load on the hydraulic support below the borehole in real time and obtains the corresponding hydraulic support load change curve.

[0048] S5 determined the critical overburden height H that affects the load of the hydraulic support at the working face by comprehensively comparing the distribution optical cable breakpoint variation curves with the hydraulic support load variation curves. MAX m;

[0049] S5.1 By comprehensively comparing the distribution optical cable break point variation curve and the hydraulic support working resistance variation curve, multiple peak values ​​p of the hydraulic support load at the working face can be measured when a break occurs in the distribution optical cable at the bottom of the borehole. imax实测 However, as the working face continues to advance, the break points of the distributed optical cable will continue to rise, but the peak load of the hydraulic support at the working face will not continue to increase and will eventually remain at a maximum peak value p. MAX实测 ,by Figure 1 For example, when the distributed optical cable experiences a breakpoint 1 in critical layer 1, the hydraulic support load exhibits its first peak value p. 1max实测 When the breakpoint 2 occurs in the critical layer 2, the hydraulic support load exhibits a second peak value p. 2max实测Subsequently, at breakpoints 3, 4, and 5, the hydraulic support load reached its peak value p. 3max实测 p 4max实测 p 5max实测 When p 2max实测 With p 3max实测 p 4max实测 p 5max实测 It is essentially a constant value, which is considered as the maximum peak value p. MAX实测 ;

[0050] S5.2 Determine the first occurrence of the maximum peak value p MAX实测 The height of the distributed optical cable break at that time is the critical overburden height H that affects the load on the hydraulic support of the working face. MAX ,by Figure 1 For example, the first occurrence of the maximum peak value p MAX实测 The time corresponds to the height of breakpoint 2, which is regarded as the critical height H of the overburden. MAX ;

[0051] S5.3, combined with S1.2, yields the critical overburden height H that affects the load on the hydraulic support at the working face. MAX The thicknesses of the rock layers within the following ranges are h1, h2, ..., h n With bulk density γ1, γ2, ..., γ n ,by Figure 1 and Figure 3 For example, the rock strata below breakpoint 2 that affect the load of the hydraulic support at the working face include 4 layers, with thicknesses of h1, h2, h3, h4 and unit weights of γ1, γ2, γ3, γ4, respectively.

[0052] S6 obtains the maximum load p of the hydraulic support at the working face based on the determined critical height of the overburden. MAX校正 (Unit: kPa) kPa, thereby correcting and calculating the maximum working resistance P of the hydraulic support at the working face. MAX校正 (Unit: kN)

[0053] S6.1 The critical overburden height H that affects the load on the hydraulic support of the working face, obtained from S5. MAX The maximum load of the hydraulic support at the working face is recalibrated and obtained using the following formula: p MAX校正 =∑h i γ i (i=1,2...,n), with Figure 1 and Figure 3 For example, the maximum load p of the corrected working face hydraulic support MAX校正 =γ1h1+γ2h2+γ3h3+γ4h4, assuming γ1=25kN / m 3 h1 = 15m, γ2 = 30kN / m 3h2 = 20m, γ3 = 25kN / m 3 h3 = 15m, γ2 = 30kN / m 3 h2 = 20m, substituting into the calculation, we get p MAX校正 =1950kPa;

[0054] S6.2 Further, the maximum working resistance of the corrected hydraulic support at the working face is obtained by the following calculation formula: P MAX校正 =(L k +L d Bp MAX校正 L k For the top distance, L d B is the length of the support top beam, and B is the support spacing. These three parameters are all fixed parameters (unit: meters). Figure 3 and Figure 4 For example, suppose L k =0.5m, L d =4.5m, B=1.5m, substituting into the calculation, we get P MAX校正 =14625kN;

[0055] S6.3 Furthermore, when selecting hydraulic supports for the working face in the subsequent process, it should be ensured that the maximum working resistance of all hydraulic supports is greater than P. MAX校正 .

[0056] Finally, the method of this invention can accurately determine the critical overburden height that affects the load on the hydraulic support of the working face after coal seam mining, and based on this, the maximum working resistance of the hydraulic support of the working face can be calculated. The above-mentioned example test method is simple and can provide a reliable reference for the selection of hydraulic supports for the working face, thus providing important data support for the management of strong mine pressure in the working face.

[0057] For those skilled in the art, various corresponding changes and modifications can be made based on the above technical solutions and concepts, and all such changes and modifications should be included within the scope of protection of the claims of this invention.

Claims

1. A method for determining the critical overburden height that affects the load on hydraulic supports at the working face and for correcting support selection, characterized in that, The method includes the following steps: S1 involves setting up a surface borehole above the ground surface in the middle of the working face, with the borehole depth reaching the roof of the coal seam being mined. After the S2 borehole construction was completed, distributed optical cables were laid from the borehole opening to the bottom of the borehole. After the distributed optical cables were laid to the bottom of the borehole, cement grout was used to seal the entire borehole to ensure that the distributed optical cable survey line was coupled with the surrounding rock of the borehole. As the working face is mined and pushes past the borehole, the distributed optical cables inside the borehole will gradually break from bottom to top due to the mining activity. S4 monitors the load on the hydraulic support below the borehole in real time and obtains the corresponding hydraulic support load change curve. S5 determined the critical overburden height H that affects the hydraulic support load by comprehensively comparing the distribution optical cable breakpoint variation curves with the hydraulic support load variation curves. MAX m; S6 corrects the critical overburden height determined in step S5 to obtain the maximum load of the hydraulic support at the working face. Finally, the maximum working resistance of the hydraulic support at the working face was obtained through correction calculations. Step S5 further includes: S5.1 By comprehensively comparing the distribution optical cable break point variation curve with the working face hydraulic support load variation curve, multiple peak values ​​of the working face hydraulic support load can be measured when a break point occurs in the distribution optical cable at the bottom of the borehole. As the working face advances, the break points of the distributed optical cable will continue to rise, and the peak load of the hydraulic support at the working face will not continue to increase but will eventually remain at a maximum peak value. S5.2 Determine the first occurrence of the maximum peak value The height of the distributed optical cable break at that time is the critical overburden height H that affects the load on the hydraulic support of the working face. MAX ; S5.3 Combined with the thickness h of each rock layer inside the entire borehole in step S1 i m, unit weight of each rock layer γ i The critical overburden height H that affects the load on the hydraulic support at the working face was obtained. MAX The thicknesses of the rock layers within the following ranges are h1, h2, ..., h n With bulk density γ1, γ2, ..., γ n . Step S6 further includes: S6.1 The critical overburden height H that affects the load of the hydraulic support at the working face, obtained in step S5. MAX The maximum load of the hydraulic support at the working face is recalibrated and obtained using the following calculation formula: The maximum working resistance of the hydraulic support at the working face after S6.2 correction is obtained by the following calculation formula: In the above formula, L k For the top distance, L d B represents the length of the support top beam and B represents the support spacing, both of which are fixed parameters. S6.3 When selecting hydraulic supports for the working face, it should be ensured that the maximum working resistance of all hydraulic supports is greater than [a certain value].

2. The method for determining the critical overburden height affecting the load of the hydraulic support at the working face and for correcting the support selection, as described in claim 1, is characterized in that... Step S1 further includes: During S1.1 drilling, core sampling shall be performed on the bedrock section excluding the topsoil section, with a core diameter of not less than 91mm. S1.2 After full-hole coring, the thickness h of each rock layer inside the entire borehole was obtained. i m, and then through mechanical testing, the unit weight γ of each rock layer can be obtained. i ; After S1.3 full-hole coring, the borehole is enlarged to facilitate the subsequent deployment of distributed optical cables.

3. The method for determining the critical overburden height affecting the load of the hydraulic support at the working face and for correcting the support selection, as described in claim 1, is characterized in that... Step S2 further includes: After the S2.1 distributed optical cable is laid to the bottom of the hole, cement grout is injected to seal the hole. The cement grout is mixed and stirred according to a certain water-cement ratio. S2.2 In order to achieve the best coupling effect between the cement grout injected into the borehole and the surrounding rock after solidification, the mechanical parameters of the solidified grout are first adjusted to be close to the mechanical parameters of each rock layer by adjusting different water-cement ratios. When sealing the borehole on site, different water-cement ratios are used to inject cement grout in sections according to different rock layers.

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