A study on the subsidence movement and stress evolution characteristics of unequally thick bedrock overburden under the extremely thick loose layer

It is of great significance for disaster prevention and control to master the movement law of overlying strata and its disaster causing mechanism under specific stratum conditions. The evolution process of overlying rock movement under the condition of unequal thickness bedrock in extremely thick loose layers has been revealed through similar simulation experiments. And the failure characteristics of the inclined funnel-shaped overlying rock, as well as its wide range of migration and large subsidence coefficient, have been obtained in experiments. In addition, the stress evolution characteristics under two different types of overlying rock structures were also obtained. Furthermore, numerical simulations were used to analyze the characteristics of overlying rock movement under the combined action of thick loose layers and unequal thickness bedrock. The focus was on analyzing the vertical stress and surface subsidence characteristics of loose layers and bedrock located in different layers during the mining process. The final part of the paper verifies the accuracy of the surface subsidence characteristics and stress analysis results under the combined action of thick and uneven bedrock layers through on-site measurements. The research results of this paper can provide reference for overlying rock movement, surface subsidence, and disaster prevention and control under similar geological conditions.