To accurately detect the development height of the water flowing fractured zone (WFFZ) in the overlying strata of the working face after mining under water and to ensure the safety and reliability of coal mining, the coal seam located under Weishanhu Lake in the Jisan coal mine was used as the experimental system. A similar laboratory simulation and water injection-based fracturing test system were used with the working face before and after mining activity to calculate, quantitatively detect, and qualitatively analyze the development height of the WFFZ in the overlying strata. Meanwhile, a flow-stress-damage model and its criterion of fracture expansion were established based on the Mohr-Coulomb criterion, and the FLAC 3D software was used to simulate the deformation and failure of the overlying strata and the evolution of WFFZ during the mining process. The results showed that the height ranges of the WFFZ beneath Weishanhu Lake of the Jisan coal mine as established by the above three methods are 30-45 m, 30-48 m, and 30-50 m. In the process of mining, the caving zone and fractured zone are, respectively, subjected to tensile failure and shear failure. The development height of the water flowing through the fractured zone in the overlying strata is basically consistent with the range of the “breaking arch.” The flow-stress-damage model and its criterion of fracture expansion can be applied to the fracture law of overlying strata under water under similar geological conditions.

Shale reservoirs are characterized by extremely low permeability and high clay content. To further study the stress sensitivity of a shale reservoir, the Lower Cambrian shale in north Guizhou was utilized. Through laboratory testing, the relationships between the shale porosity and permeability and the effective stress were established, and the stress sensitivity of shale was analysed. The mechanical properties and mineral composition of this shale were studied by rock mechanics testing and X‐ray diffraction. The main factors affecting the stress sensitivity were analysed. The results show that the porosity and permeability of this shale decrease with increasing effective stress; the shale reservoir permeability damage rate is 61.44 ~ 73.93%, with an average of 69.92%; the permeability stress sensitivity coefficient is 0.04867 ~ 0.05485 MPa⁻¹, with an average of 0.05312 MPa⁻¹; and the shale reservoir stress sensitivity is strong. Shale stress sensitivity is related to the rock mineral composition and rock mechanical properties. The higher the clay content in the mineral composition, the lower the elastic modulus of shale, the higher the compressibility, and the greater the stress sensitivity coefficient.

In this study, the analysis and control of stability of surrounding rock in deep fractured soft rock roadway located in the underground mine of Jinfeng gold mine in Guizhou Province, China, has been investigated. The surrounding rock of roadway has been analyzed to characterize its deformation and failure mechanism through field survey, testing of rock physical and mechanical properties, in situ stress measure, analysis of mineral components of rock, and investigation of rock fragmentation degree. Based on the numerical simulation technology, the influence of different factors on the stability of roadway is studied. The physical and mechanical properties of surrounding rock and the bearing capacity of surrounding rock layer are to be improved to maintain the stability of broken soft rock roadway as high ground stress, rock fragmentation, and poor lithology leading to tunnel instability. Hence, a high‐strength “cable bolt + fiber‐reinforced shotcrete + steel mesh + split sets + resin bolt + cement grouting” combined support system has been proposed to improve the effective bearing structure significantly with high integrity and bearing capacity.