Geomechanics model test research on large deformation control mechanism of roadway disturbed by strong dynamic pressure

Abstract

Comprehensive mechanized top-coal caving mining is one of the efficient mining methods in coal mines. How- ever, the goaf formed by comprehensive mechanized top-coal caving mining is high, and the goaf roof collapse will cause strong dynamic pressure disturbance, especially the collapse of thick hard roof. Strong dynamic pressure disturbance has an influence on the stability of the roadway, which can lead to large deformation. In order to solve the above problem, a comprehensive pressure releasing and constant resistance energy absorbing control method is proposed. Comprehensive pressure releasing can change the roadway roof structure and cut off the stress transfer between goaf and roadway, which can improve the stress environment of the roadway. The constant resistance energy absorbing (CREA) anchor cable can absorb the energy of surrounding rock deformation and resist the impact load of gangue collapse, so as to ensure the stability of roadway disturbed by strong dynamic pressure. A three-dimensional geomechanics model test is carried out, based on the roadway disturbed by strong dynamic pressure of the extra-large coal mine in western China, to verify the control effect of the new control method. The stress and displacement evolution laws of the roadway with traditional control method and new control method are analyzed. The pressure releasing and energy absorbing control mechanism of the new control method is clarified. The geomechanics model test results show that the new control method can increase the range of low stress zone by 150% and reduce the average stress and the displacement by 34.7% and 67.8% respectively, compared with the traditional control method. The filed application results show that the new control method can reduce the roadway surrounding rock displacement by 67.4% compared with the traditional control method. It shows that the new control method can effectively control the displacement of the roadway disturbed by strong dynamic pressure and ensure that the roadway meets the safety requirements. On this basis, the engineering suggestions for large deformation control of this kind of roadway are put forward. The new control method can provide a control idea for the roadway disturbed by strong dynamic pressure.

Keywords

Comprehensive mechanized top-coal cavingmining / Strong dynamic pressure / Thick hard roof / Geomechanics model test / Pressure releasing and energy absorbing / mechanism

References

[1] H.Y. Lv, Z.B. Cheng, F. Liu, Study on the mechanism of a new fully mechanical mining method for extremely thick coal seam, Int. J. Rock Mech. Min. Sci. 142 ( 2022), 1047887.

[2] J.H. Wang, Development and prospect on fully mechanized mining in Chinese coal mines, International Journal of Coal Science and Technology 1 (3) ( 2014) 253-260.

[3] M.C. He, Q. Wang, Excavation compensation method and key technology for surrounding rock control, Eng. Geol. 307 ( 2022), 106784.

[4] H.J. Jiang, S.G. Cao, Y. Zhang, et al., Analytical solutions of hard roof's bending moment, deflection and energy under the abutment pressure before periodic weighting, Int. J. Min. Sci. Technol. 26 (1) ( 2016) 175-181.

[5] W.D. Pan, X.D. Nie, X.Y. Li, Effect of pre-mining on hard roof distress behavior: a case study, Rock Mech. Rock Eng. 52 (6) ( 2019) 1871-1885.

[6] Q. Wang, Y. Wang, M.C. He, et al., Experimental research and application of automatically formed roadway without advance tunneling, Tunn. Undergr. Space Technol. 114 ( 2021), 103999.

[7] Y. Chen, S.Y. Zhu, Z.G. Wang, et al., Deformation and failure of floor in mine with soft coal, soft floor, hard roof and varying thicknesses of coal seam, Eng. Fail. Anal. 115 ( 2020), 104653.

[8] C. Li, H.P. Xie, M.Z. Gao, et al., Case study on the mining-induced stress evolution of an extra-thick coal seam under hard roof conditions, Energy Sci. Eng. 8 (9) ( 2020) 3174-3185.

[9] P. Konicek, K. Soucek, L. Stas, et al., Long-hole destress blasting for rockburst control during deep underground coal mining, Int. J. Rock Mech. Min. Sci. 61 ( 2013) 141-153.

[10] C. Zhang, J.P. Zou, X.F. Zhang, et al., Study on the mechanism of weakening thick and hard roof by deep-hole blasting in deep coal mines, Front. Earth Sci. 10 ( 2022), 933192.

[11] L.X. Xie, W.B. Lu, Q.B. Zhang, et al., Analysis of damage mechanisms and optimization of cut blasting design under high in-situ stresses, Tunn. Undergr. Space Technol. 66 ( 2022) 19-33.

[12] A.L. Lu, L.M. Dou, J.Z. Bai, et al., Mechanism of hard-roof rock burst control by the deep-hole blasting: numerical study based on particle flow, Shock Vib. ( 2021), 9527956, 2021.

[13] J.W. Zheng, W.J. Ju, X.D. Sun, et al., Analysis of hydro-fracturing technique using ultra-deep boreholes for coal mining with hard roofs: a case study, Mining Metallurgy and Exploration 38 ( 2021) 471-484.

[14] B.W. Xia, X. Zhang, B. Yu, et al., Weakening effects of hydraulic fracture in hard roof under the influence of stress arch, Int. J. Min. Sci. Technol. 28 (6) ( 2018) 951-958.

[15] B.X. Huang, Y.Z. Wang, S.G. Cao, et al., Cavability control by hydraulic fracturing for top coal caving in hard thick coal seams, Int. J. Rock Mech. Min. Sci. 74 ( 2015) 45-57.

[16] S.Q. Ma, Y. Chen, Application of hydraulic fracturing and energy-absorption rock bolts to improve the stability of a gob-side roadway in a 10-m-thick coal seam: case study, Int. J. GeoMech. 17 (12) ( 2015), 05017002.

[17] M.C. He, G.L. Zhu, Z.B. Guo, Longwall mining “cutting cantilever beam theory” and 110 mining method in China—the third mining science innovation, J. Rock Mech. Geotech. Eng. 7 (5) ( 2015) 483-492.

[18] M.C. He, Q. Wang, Q.Y. Wu, Innovation and future of mining rock mechanics, J. Rock Mech. Geotech. Eng. 13 (1) ( 2021) 1-21.

[19] Q. Wang, M.C. He, S.C. Li, et al., Comparative study of model tests on automatically formed roadway and gob-side entry driving in deep coal mines, Int. J. Min. Sci. Technol. 31 (4) ( 2021) 591-601.

[20] Q. Wang, M.C. He, J. Yang, et al., Study of a no-pillar mining technique with automatically formed gob-side entry retaining for longwall mining in coal mines, Int. J. Rock Mech. Min. Sci. 110 ( 2018) 1-8.

[21] M.C. He, P.F. Guo, J. Wang, et al., Experimental study on gob-side entry formed by roof cut of broken roof at shallow depth of Hecaogou No. 2 Coalmine, Chin. J. Geotech. Eng. 40 ( 2018) 391-398.

[22] X.M. Sun, X. Liu, G.F. Liang, et al., Study on key parameters of gob-side entry retaining by roof cutting and pressure releasing in thin coal seam, Chin. J. Rock Mech. Eng. 33 ( 2014) 1449-1456.

[23] Q. Wang, Z.H. Jiang, B. Jiang, et al., Research on an automatic roadway formation method in deep mining areas by roof cutting with high-strength bolt-grouting, Int. J. Rock Mech. Min. Sci. 128 ( 2020), 104264.

[24] Q. Wang, B. Jiang, S. Xu, et al., Roof-cutting and energy-absorbing method for dynamic disaster control in deep coal mine, Int. J. Rock Mech. Min. Sci. 158 ( 2022), 105186.

[25] Q. Wang, S. Xu, M.C. He, et al., Dynamic mechanical characteristics and application of constant resistance energy-absorbing supporting material, Int. J. Min. Sci.Technol. 32 ( 2022) 447-458.

[26] Q. Wang, Q. Qin, B. Jiang, et al., Geomechanics model test research on automatically formed roadway by roof cutting and pressure releasing, Int. J. Rock Mech. Min. Sci. 135 ( 2020), 104506.

[27] Q. Wang, Z.H. Jiang, B. Jiang, et al., Research on an automatic roadway formation method in deep mining areas by roof cutting with high-strength bolt-grouting, Int. J. Rock Mech. Min. Sci. 128 ( 2020), 104264.

[28] P.K. Kaiser, M. Cai, Design of rock support system under rockburst condition, J. Rock Mech. Geotech. Eng. 4 (3) ( 2012) 215-227.

[29] H.P. Kang, Seventy years development and prospects of strata control technologies for coal mine roadways in China, Chin. J. Rock Mech. Eng. 40 (1) ( 2012) 1-30 (in Chinese).

[30] J.F. Pan, Q.X. Qi, S.H. Liu, et al., Properties, types and prevention and control technology of rock burst in deep coal mining in China, J. China Coal Soc. 45 (1) ( 2020) 111-121 (in Chinese).

[31] R.S. Yang, Y.L. Li, M.S. Wang, et al., Experimental study of shear mechanical properties of prestressed cable bolts[J], J. China Univ. Min. Technol. 47 (6) ( 2018) 1166-1174 (in Chinese.).

[32] H.P. Kang, J. Lin, Y.Z. Wu, Development of high pretensioned and intensive supporting system and its application in coal mine roadways, Procedia Earth and Planetary Science 1 (1) ( 2009) 479-485.

[33] A. Mirzaghorbanali, H. Rasekh, N. Aziz, et al., Shear strength properties of cable bolts using a new double shear instrument, experimental study, and numerical simulation, Tunn. Undergr. Space Technol. 70 ( 2017) 240-253.

[34] Q. Wang, S. Xu, Z.X. Xin, et al., Mechanical properties and field application of constant resistance energy-absorbing anchor cable, Tunn. Undergr. Space Technol. 125 ( 2022), 104526.

[35] Q. Wang, S. Xu, M.C. He, et al., Dynamic mechanical characteristics and application of constant resistance energy-absorbing supporting material, Int. J. Min. Sci.Technol. 32 ( 2022) 447-458.