Physical analog simulation analysis and its mechanical explanation on dynamic load impact

In this paper,an overlying strata breakage prediction experiment platform was developed and used to simu- late the dynamic load impact in shallow working face with thin-bedrock. A breaking model of roof strata based on the elastic foundation beam model was proposed to calculate the relative position between main roof’ s breaking and coal wall and analyze the sphere of dynamic loading. According to the mechanical model of roof movement and the stress- strain curve of uniaxial compression tests,the maximum dynamic load and support’s contraction were solved under dif- ferent situations by using the principle of work and power,the criterion of no supports crushing was obtained,and the physical analog simulation result was explained. The results show that the main roof always breaks ahead of its support- ing edge,so dynamic load impact often occurs on support. And the maximum load is related to the immediate roof’ s thickness,the crack’s development degree,the support’s stiffness and the initial support force and so on. Its value is far greater than the static load on the hydraulic support formed by overlying strata. The physical analogous simulation validated the mechanical analysis results.