Study on deformation characteristics of room-and-pillar mined-out area based on physical simulation test

The room-and-pillar mined-out area has the characteristics of small recovery rate and large coal pillar, and its overburden movement law and surface deformation law are quite different from those of long-wall mined-out area. In the case of coal pillar failure, the surface will produce large deformation, threatening the safety of surface structures. In order to study the deformation and development mechanism of overlying rock and unconsolidated formation in shallow and gently tilted room-and-pillar mined-out area, based on PIV image processing technology and modular assembly idea, a physical model was established in the laboratory to carry out physical simulation experiments, inversion of the deformation and development process of overlying rock and unconsolidated formation in room-and-pillar mined-out area, and analysis of the deformation mechanism of overlying rock and unconsolidated formation under the condition of room-and-pillar mining and coal pillar instability. The research results show that: ① the ove