Overlying strata critical height judgment and support type selection correction method with influence on working face hydraulic support load

Abstract

The invention provides a method for judging the critical height of overlying strata and correcting model selection of a support, which has influence on the load of a hydraulic support on a working face. At present, the overlying strata height influencing the working face hydraulic support load is mainly estimated through a theoretical calculation method, and an effective accurate judgment method is lacked. According to the method, a distributed optical cable breakpoint curve in the overburden strata and a working face hydraulic support load change curve are compared and analyzed, and the overburden strata critical height which can influence the working face hydraulic support load after coal mining is determined according to the corresponding relation of the two curves. On the basis, the maximum working resistance of the working face hydraulic support is obtained through correction calculation, and therefore an accurate basis is provided for parameter determination during follow-up working face hydraulic support model selection. Compared with other methods, the method is simple, convenient and reliable, and can provide important data support for working face strong mine pressure treatment.

Description

Technical Field

[0001] The invention relates to the technical field of mine safety prevention and control, and in particular to a method for distinguishing a critical height of overburden rock that affects a hydraulic support load on a working face and for selecting and correcting a support. Background Art

[0002] Traditional related theories believe that the rock strata that affect the load of the hydraulic support on the working face are mainly below the old roof. Therefore, when selecting the hydraulic support for the working face, the overburden load that is mainly considered is also limited to the old roof range. With the continuous increase in the depth and thickness of coal seam mining, the impact range of working face mining on the overburden strata is also increasing. Compared with the shallower or thinner coal seams in the past, the overburden height that affects the working resistance of the hydraulic support on the working face has also increased, and is no longer limited to below the old roof range. Therefore, when selecting the hydraulic support for the working face, it is first necessary to determine the overburden height range that will affect the working face after coal seam mining, so as to more accurately calculate the overburden load that affects the working resistance of the hydraulic support, thereby providing reliable data support for the selection of hydraulic supports.

[0003] The main methods for calculating the working resistance of the hydraulic support of the working face include load estimation method, measured statistical method and theoretical analysis method. Among them, the overburden height selected for estimating the load of the hydraulic support of the working face in the load estimation method is 4 to 8 times the mining height. The load of the hydraulic support of the working face obtained on this basis is not accurate enough; the measured statistical method requires a large number of working face statistical values ​​as a basis, and the calculation workload is large; there are multiple assumptions or fuzzy parameters in the theoretical analysis method. All of the above methods have some disadvantages.

[0004] This method arranges distributed optical cables inside the boreholes by arranging ground holes, and compares and analyzes the strain breakpoint curve of the distributed optical cable with the load curve of the hydraulic support of the working face. The critical height of the overburden that will affect the load of the hydraulic support of the working face after coal seam mining is determined according to the corresponding relationship between the two types of curves. On this basis, the maximum working resistance of the hydraulic support of the working face can be corrected and calculated. Compared with other methods, this method is both simple and reliable. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention aims to provide a method for determining the critical height of overburden that affects the load of hydraulic supports on a working face and for selecting and correcting a support.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] A method for determining the critical height of overburden that affects the load of hydraulic supports on a working face and for selecting and correcting supports comprises the following steps:

[0008] S1 Arrange a ground borehole above the ground surface in the middle of the working face, and the drilling depth can reach the top of the mined coal seam;

[0009] After the S2 drilling construction is completed, the distributed optical cable is laid from the ground hole to the bottom of the hole. After the distributed optical cable is laid to the bottom of the hole, cement slurry is used to seal the entire borehole to ensure the coupling between the distributed optical cable measurement line and the surrounding rock of the borehole;

[0010] S3 As the working face is mined and pushed through the borehole, the distributed optical cables inside the borehole will be gradually broken from bottom to top due to the impact of mining;

[0011] S4 monitors the load of the hydraulic support on the working surface below the borehole in real time, and can obtain the corresponding load change curve of the hydraulic support on the working surface;

[0012] S5 determines the critical height H of the overburden that affects the load of the hydraulic support on the working face by comprehensively comparing the change curve of the distributed optical cable breakpoint and the change curve of the hydraulic support load on the working face. MAX m;

[0013] S6 can correct the maximum load p of the hydraulic support on the working face according to the determined critical height of the overburden rock MAX校正 (Unit: kPa), and then correct and calculate the maximum working resistance P of the hydraulic support on the working surface MAX校正 (Unit: kN).

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

[0015] S1.1 During drilling construction, the whole hole shall be cored in the bedrock section except the surface soil section. In order to facilitate the subsequent mechanical testing, it is recommended that the core diameter should not be less than 91mm;

[0016] S1.2 After coring the entire hole, the thickness of each rock layer inside the entire borehole can be obtained. i m, the bulk density γ of each rock layer can be obtained through mechanical testing i (Unit: kN / m 3 );

[0017] S1.3 In order to facilitate the subsequent deployment of distributed optical cables, the borehole can be further expanded after full-hole coring.

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

[0019] S2.1 After the distributed optical cable is arranged at the bottom of the hole, grouting and sealing are required. The cement slurry 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 borehole grouting and the surrounding rock after solidification, the mechanical parameters of the slurry after solidification can be made close to the mechanical parameters of each rock layer by adjusting different water-cement ratios. When sealing the hole on site, different water-cement ratios can be used according to different rock layers for segmented grouting and sealing.

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

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

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

[0024] S5.3 Combining step S1.2, we can get the critical height H of overburden that affects the load of hydraulic support on the working face. MAX The thickness of each rock layer within the following range is h1, h2, ..., h n and bulk density γ1,γ2,……,γ n .

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

[0026] S6.1 Based on S5, the critical height H of the overburden that affects the hydraulic support load on the working face MAX , recalibrate the maximum load of the hydraulic support on the working surface, which can be obtained by the following calculation formula: MAX校正 =∑h i γ i (i=1,2……,n);

[0027] S6.2 Further, the maximum working resistance of the hydraulic support on the working face after correction can be obtained by the following calculation formula: P MAX校正 =(L k +L d ) MAX校正 , where L k is the empty head distance, L d is the length of the bracket top beam, and B is the bracket spacing, both of which are fixed parameters (both in m);

[0028] S6.3 Further, when selecting the hydraulic support for the working face, it should be ensured that the maximum working resistance of the hydraulic support is greater than P MAX校正 .

[0029] The beneficial effects of the present invention are:

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

[0031] 2. The identification method of the present invention is simple and can provide a reliable reference for the selection of hydraulic supports on the working face, thereby providing important data support for the management of strong mine pressure on the working face. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram comparing the breakpoint variation curve of the distributed optical cable inside the borehole and the load variation curve of the hydraulic support on the working surface in the embodiment of the present invention;

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

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

[0035] Figure 4 is the top beam length L of the hydraulic support on the working surface in the embodiment of the present invention d , schematic diagram of bracket spacing B. DETAILED DESCRIPTION

[0036] The present invention will be further described below in conjunction with the accompanying drawings. It should be noted that this embodiment is based on the technical solution and provides a detailed implementation method and specific operation process, 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 height of overburden that affects the load of hydraulic supports on a working surface and for selecting and correcting the support type, the method comprising the following steps:

[0039] S1 Arrange a ground borehole above the ground surface in the middle of the working face, and the drilling depth can reach the top of the mined coal seam:

[0040] S1.1 During drilling construction, the whole hole shall be cored in the bedrock section except the surface soil section. In order to facilitate the subsequent mechanical testing, it is recommended that the core diameter should not be less than 91mm;

[0041] S1.2 After coring the entire hole, the thickness of each rock layer inside the entire borehole can be obtained. i m, the bulk density γ of each rock layer can be obtained through mechanical testing i (Unit: kN / m 3 );

[0042] S1.3 In order to facilitate the subsequent deployment of distributed optical cables, the borehole can be further expanded after full-hole coring.

[0043] After the S2 drilling construction is completed, the distributed optical cable is laid from the ground hole to the bottom of the hole. After the distributed optical cable is laid to the bottom of the hole, cement slurry is used to seal the entire borehole to ensure the coupling between the distributed optical cable measurement line and the surrounding rock of the borehole:

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

[0045] S2.2 In order to achieve the best coupling effect between the grouting and the surrounding rock after solidification, the mechanical parameters of the grouting after solidification can be adjusted to be close to the mechanical parameters of each rock layer. When sealing the hole on site, different water-cement ratios are used according to different rock layers for segmented grouting and sealing. The effect is as follows: Figure 2 shown.

[0046] S3 As the working face is mined and pushed through the borehole, the distributed optical cables inside the borehole will be gradually broken from bottom to top due to the impact of mining;

[0047] S4 monitors the load of the hydraulic support on the working surface below the borehole in real time, and can obtain the corresponding load change curve of the hydraulic support on the working surface;

[0048] S5 determines the critical height H of the overburden that affects the load of the hydraulic support on the working face by comprehensively comparing the change curve of the distributed optical cable breakpoint and the change curve of the hydraulic support load on the working face. MAX m;

[0049] S5.1 By comprehensively comparing the distributed optical cable breakpoint change curve and the hydraulic support working resistance change curve, when the distributed optical cable at the bottom of the borehole breaks, multiple peak values ​​of the hydraulic support load on the working face p can be measured. imax实测 However, as the working face continues to advance, the breakpoint of the distributed optical cable will continue to rise, but the peak load of the hydraulic support on the working face will not continue to rise and eventually remain at a maximum peak value p MAX实测 ,by Figure 1 For example, when the distributed optical cable has a breakpoint 1 at key layer 1, the hydraulic support load has the first peak value p 1max实测 When the breakpoint 2 appears in the key layer 2, the hydraulic support load has a second peak value p 2max实测Then, the hydraulic support load peaks at breakpoints 3, 4, and 5. 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 basically a constant value, which is regarded as the maximum peak value p MAX实测 ;

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

[0051] S5.3 Combined with S1.2, the critical height H of overburden that affects the load of hydraulic support on the working face can be obtained. MAX The thickness of each rock layer within the following range is h1, h2, ..., h n and bulk density γ1,γ2,……,γ n ,by Figure 1 and Figure 3 For example, there are four rock layers below breakpoint 2 that affect the load of the hydraulic support on the working face, and the thickness of each rock layer is h1, h2, h3, h4, and the bulk density is γ1, γ2, γ3, γ4 respectively.

[0052] S6 can correct the maximum load p of the hydraulic support on the working face according to the determined critical height of the overburden rock MAX校正 (Unit: kPa) kPa, thus correcting and calculating the maximum working resistance P of the hydraulic support on the working surface MAX校正 (Unit: kN).

[0053] S6.1 Based on S5, the critical height H of the overburden that affects the hydraulic support load on the working face MAX , recalibrate the maximum load of the hydraulic support on the working surface, which can be obtained by the following calculation formula: 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 hydraulic support on the working face after correction MAX校正 =γ1h1+γ2h2+γ3h3+γ4h4, assuming γ1=25kN / m 3 , h1=15m,γ2=30kN / m 3, h2=20m,γ3=25kN / m 3 , h3=15m,γ2=30kN / m 3 , h2=20m, and we can get p MAX校正 =1950kPa;

[0054] S6.2 Further, the maximum working resistance of the hydraulic support on the working face after correction can be obtained by the following calculation formula: P MAX校正 =(L k +L d ) MAX校正 , where L k is the empty head distance, L d is the length of the bracket top beam, B is the bracket spacing, both are fixed parameters (unit is m). Figure 3 and Figure 4 For example, assuming L k =0.5m, L d =4.5m, B=1.5m, substituting into the calculation, we can get P MAX校正 =14625kN;

[0055] S6.3 Further, when selecting the hydraulic support for the working face, it should be ensured that the maximum working resistance of the hydraulic support is greater than P MAX校正 .

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

[0057] For those skilled in the art, various corresponding changes and modifications can be made according to the above technical solutions and concepts, and all of these changes and modifications should be included in the protection scope of the claims of the present invention.

Claims

1. A method for determining the critical height of overburden and selecting and correcting the support type that affects the load of hydraulic support on a working face, characterized in that: The method comprises the following steps: S1 Arrange a ground borehole above the ground surface in the middle of the working face, and the drilling depth can reach the top of the mined coal seam; After the S2 drilling construction is completed, the distributed optical cable is laid from the ground hole to the bottom of the hole. After the distributed optical cable is laid to the bottom of the hole, cement slurry is used to seal the entire borehole to ensure the coupling between the distributed optical cable measurement line and the surrounding rock of the borehole; S3 As the working face is mined and pushed through the borehole, the distributed optical cables inside the borehole will be gradually broken from bottom to top due to the impact of mining; S4 monitors the working resistance of the hydraulic support below the borehole in real time, and can obtain the corresponding change curve of the working resistance of the hydraulic support; S5 determines the critical height H of the overburden that affects the load of the hydraulic support by comprehensively comparing the distributed optical cable breakpoint change curve with the load change curve of the hydraulic support on the working face. MAX m; S6 The maximum load p of the hydraulic support on the working face can be corrected according to the critical height of the overburden determined in step S5. MAX校正 Finally, the maximum working resistance P of the hydraulic support on the working surface is obtained through correction calculation MAX校正 .

2. The method for determining the critical height of overburden affecting the load of hydraulic support on the working face and correcting the support selection according to claim 1 is characterized in that: The step S1 further comprises: S1.1 During drilling construction, the whole hole shall be cored in the bedrock section except the topsoil section, and the core diameter shall not be less than 91mm; S1.2 After coring the entire hole, the thickness of each rock layer inside the entire borehole is obtained h i m, and then the bulk density γ of each rock layer can be obtained through mechanical testing i ; S1.3 After full-hole coring, the borehole can be expanded to facilitate the subsequent deployment of distributed optical cables.

3. The method for determining the critical height of overburden affecting the load of hydraulic support on the working face and correcting the support selection according to claim 1 is characterized in that: The step S2 further comprises: S2.1 After the distributed optical cable is arranged at the bottom of the hole, cement slurry is poured to seal the hole, wherein the cement slurry is mixed and stirred according to a certain water-cement ratio; S2.2 In order to achieve the best coupling effect between the cement slurry injected into the borehole and the surrounding rock after solidification, the mechanical parameters of the slurry after solidification can be made close to the mechanical parameters of each rock layer by adjusting different water-cement ratios. When sealing the hole on site, different water-cement ratios can be used according to different rock layers to perform segmented cement slurry sealing.

4. The method for determining the critical height of overburden affecting the load of hydraulic support on the working face and correcting the support selection according to claim 1 is characterized in that: The step S5 further comprises: S5.1 By comprehensively comparing the distributed optical cable breakpoint change curve and the working face hydraulic support load change curve, when the distributed optical cable at the bottom of the borehole has a breakpoint, multiple peak values ​​p of the working face hydraulic support load can be measured. imax实测 As the working face continues to move forward, the breakpoint of the distributed optical cable will continue to rise, and the peak load force of the hydraulic support on the working face will not continue to increase and eventually remain at a maximum peak value p MAX实测 ; S5.2 Determine the first occurrence of the maximum peak p MAX实测 The corresponding breakpoint height of the distributed optical cable is the critical height H of the overburden that affects the load of the hydraulic support on the working face. MAX ; S5.3 Combine the thickness of each rock layer in the entire borehole h in step S1 i m, bulk density of each rock layer γ i The critical height H of the overburden that affects the load of the hydraulic support on the working face can be obtained. MAX The thickness of each rock layer within the following range is h1, h2, ..., h n and bulk density γ1,γ2,……,γ n .

5. The method for determining the critical height of overburden affecting the load of hydraulic support on the working face and correcting the support selection according to claim 1, characterized in that: The step S6 further comprises: S6.1 The critical height H of the overburden that affects the load of the hydraulic support on the working face obtained in step S5 MAX , recalibrate the maximum load of the hydraulic support on the working surface, which can be obtained by the following calculation formula: S6.2 The maximum working resistance of the hydraulic support on the working face after correction can be obtained by the following calculation formula: In the above formula, L k is the empty head distance, L d is the length of the bracket top beam and B is the bracket spacing, both of which are fixed parameters; S6.3 When selecting hydraulic supports for the working face, the maximum working resistance of the hydraulic supports should be greater than

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