Analysis on the distribution and formation mechanism of ground collapse in gypsum mining area in Yingcheng of Hubei Province

Geological disasters of ground collapse in mining area have a significant impact on infrastructure, such as roads, pipelines, residents’ lives and property, and safety production in mining area. Yingcheng gypsum mine in Hubei Province has a mining history of nearly 400 years, and long-term underground mining has formed a large range of goaf and ground collapse. Based on the systematic collection of pre-mining data and supplementary survey, the types and distribution rules of ground collapse were analyzed by multi-factor comprehensive and geological method. Based on the theory of "three zones", the cause mechanism of ground collapse of old hole type and mining cavity type were studied. The research shows that the ground collapse of gypsum mine is mainly small to medium in Yingcheng, and the geological hazards of ground collapse are divided into mining cavity type and old hole type. The caving type of ground collapse mainly includes two types: pillar breakage type and bending settlement type. Pillar breakage type is mainly the pillar and roof collapse caused by room and pillar mining, and bending settlement type is mainly the roof collapse caused by insufficient filling rate of longwall filling method mining. The main controlling factors of goaf-type surface collapse are the goaf filling condition and the ratio of depth to thickness. When the ratio of depth to thickness is less than 60, the surface collapse occurs more often, and with the increase of the ratio of depth to thickness, the ground collapse gradually decreases. The degree of subsidence deformation in the old hole type depends on whether the old hole is connected with the large-scale goaf and whether it is filled with water. The research results have guiding significance for gypsum mine risk management, safety assessment, monitoring and early warning system construction.