Main geological and mining factors affecting ground cracks induced by underground coal mining in Shanxi Province, China

As one of the largest coal-rich provinces in China,Shanxi has extensive underground coal-mining operations.These operations have caused numerous ground cracks and substantial environmental damage.To study the main geological and mining factors influencing mining-related ground cracks in Shanxi,a detailed investigation was conducted on 13 mining-induced surface cracks in Shanxi.Based on the results,the degrees of damage at the study sites were empirically classified into serious,moderate,and minor,and the influential geological and mining factors(e.g.,proportions of loess and sandstone in the mining depth,ratio of rock thickness to mining thickness,and ground slope)were discussed.According to the analysis results,three factors(proportion of loess,ratio of rock thickness to mining thickness,and ground slope)play a decisive role in ground cracks and can be respectively considered as the critical material,mechanical,and geometric conditions for the occurrence of mining surface disasters.Together,these three factors have a strong influence on the occurrence of serious discontinuous ground deformation.The results can be applied to help prevent and control ground damage caused by coal mining.The findings also provide a direct reference for predicting and eliminating hidden ground hazards in mining areas.

Characteristics of ground cracks caused by the M_(S) 6.4 Yangbi earthquake and the corresponding tectonic significance

An M_(S)6.4 earthquake occurred near Yangbi County, Dali Bai Autonomous Prefecture, Yunnan Province, at 21:48on May 21, 2021. The earthquake location is characterized by complex geological structures, with multiple active faults distributed around the epicenter that is located at the west edge of the Sichuan-Yunnan rhombic block(25.67°N, 99.87°E). A total of 42 ground cracks are found by earthquake field investigations. The cracks are mainly concentrated in the Ⅷ degree area on the west side of the Yangbi River. Among these, 9 coseismic tectonic ground cracks generated by shear fractures are found in three villages(i.e., Akechang, Meijia-Lijia, and Huajiazhuang), which are distributed along the strike of the northwest-trending linear folds, showing the tectonic characteristics of right-lateral tension or left-stepping cracks. The structural attribute of ground cracks sustains the kinematic properties of the Weixi-Qiaohou fault, namely right-lateral strike-slip.