Failure characteristics of weakly cemented overburden strata and compaction response behavior of caving materials in shadow buried panels: A study in Western China
Jingzhong Zhu, Wenping Li, Dongding Li, Qiqing Wang, Xiaoqin Li
Abstract
• Break heat generated by strata damage in the matrix discrete element method (MatDEM) identifies the mining-induced fracture distribution. • An improved method of the WCFZ is proposed. Dry drilling and upward segmental water injection detect the weakly cemented strata fissures. • A fiber grating sensor online monitoring system (FGSOMS) is built to realize the caving materials compaction features. Accidents and ecological environment deterioration associated with mining operations are prevalent, especially in Western China quarries, where special geological sedimentation forms the weakly cemented strata. The physical properties of the weakly cemented rocks are contrasted with those of the rocks from eastern China. Besides, this study investigates the mining-induced failure of the overburden through MatDEM software and field measurements. A fiber grating sensor online monitoring system was built to obtain the response feature of caving materials. The results indicate the mechanical strength of mudstone and siltstone is greater than that of sandstone, which is the reverse in eastern China. In addition, the natural porosity is greater than that of rocks in the eastern region. The development height of the mining-induced failure, including water-conducting fractured zone and caving zone, varies from 142.95 m to 152 m. The predicted value obtained through the empirical formula deviates greatly from the measured value. The range of the caving zone is indirectly calculated to be 47.80 m through the pressure sensor. The cyclic processes of crack compaction and formation lead to fluctuations in osmotic water pressure. Caving materials exhibit excellent water absorption and retention properties. Field water temperature measurement explains why the sensor temperature changes. This study provides valuable insights into the failure mechanisms of the weakly cemented overburden and the compaction behavior of caving materials.