Numerical Study on Characteristics of Bedrock and Surface Failure in Mining of Shallow-Buried MCS

Guangchun Liu, Wenzhi Zhang, Youfeng Zou, Huabin Chai and Yongan Xue
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Guangchun Liu: School of Surveying and Land Information, Henan Polytechnic University, Jiaozuo 454000, China
Wenzhi Zhang: School of Surveying and Land Information, Henan Polytechnic University, Jiaozuo 454000, China
Youfeng Zou: School of Surveying and Land Information, Henan Polytechnic University, Jiaozuo 454000, China
Huabin Chai: School of Surveying and Land Information, Henan Polytechnic University, Jiaozuo 454000, China
Yongan Xue: School of Surveying and Land Information, Henan Polytechnic University, Jiaozuo 454000, China

Energies, 2022, vol. 15, issue 9, 1-18

Abstract: Coal is one of the important energy sources for industry. When it is mined, it will cause the destruction of bedrock and surface. However, it is more severe in mining shallow-buried multi coal seams (SBMCS). To better reveal the characteristics of the bedrock and surface damage, we have carried out a theoretical analysis, as well as used numerical simulations and field monitoring methods to study the surface and bedrock damage caused by the mining of SBMCS. The characteristics of bedrock and surface failure structure, settlement, and stress distribution were studied and analyzed. The findings show that the collapsed block, formed by the rupture of the overlying stratum, interacts with the surrounding rock to form large cavities and gaps, and the stress concentration occurs between them. The maximum downward vertical concentration stress is about 9.79 MPa. The mining of the lower coal seam can lead to repeated failure of the upper bedrock and goaf. The settlement of bedrock presents gradient change, and the settlement of upper bedrock is large, about 8.0 m, and the maximum settlement is 8.183 m, while that of lower bedrock is small and about 3.5–4.0 m. The weak rock stratum in the bedrock is crushed by the change stress of repeated mining, and formed a broken rock stratum. The cracks in the bedrock develop directly to the ground. On the ground, tensile cracks, compression uplift, stepped cracks, and even collapse pits are easy to cause in mining SBMCS. Affected by repeated mining, the variation of surface vertical stress is complex and disorderly in the middle of the basin, and the variation of horizontal stress is mainly concentrated on the edge of the basin. The maximum stress reaches 100 KPa, and the minimum stress is about 78 KPa. Through theoretical analysis and discussion, the size of the key blocks is directly related to the thickness and strength of the rock stratum.

Keywords: coal mining; multi coal seam; CDEM; numerical simulation; bedrock failure; surface damage (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2022
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