Deformation and Stability in Coal Seam Mining Under Fluid–Solid Coupling

Reasonable retention of safe coal and rock pillars is significant for safe mining and liberating coal resources under thick loose aquifers. The 18,041 working face of Chengcun Mine is taken as the research background. The elastic foundation model of the rock-clay synergistic aquiclude was creatively constructed, and the structural instability criterion was derived. The dynamic evolution law of thin bedrock failure and the vertical settlement law of clay layer are studied by numerical simulation test. A similar material simulation test is used to simulate the development law of water flowing fractured zone and the evolution law of vertical displacement of rock strata under the condition of fluid–solid coupling and to verify the stability of rock-clay synergistic water-resisting structure. The research shows that: (1) The maximum tensile stress in the middle of the long side of the rock stratum at the top of the bedrock is 0.652 MPa, less than its tensile strength threshold. (2) The clay and rock layers at the top of the bedrock have a synergistic settlement. The vertical settlement distribution transitions from a 'concentric circle' to a 'concentric ellipse'. The maximum deformation value in the central area is 0.5 m. (3) The development of water-conducting fractures under the thick loose layer and thin bedrock presents a 'double peak and one valley' shape, with a maximum height of 45.2 m. The rock-clay synergistic water-resisting structure maintains the effective water-resisting property, thus verifying the feasibility of the 4 m mining scheme.