Physical model for deformation-failure evolution of double gob-side entry

In order to analyze the instability and failure of the double gob-side entry, the deformation-failure evolution, the deformation law of the surrounding rock and the rock rupture modes are studied by using the methods of physical model and digital photogrammetry. The results show that in the roadway-arrangement system of the double gob-side entry, the middle pillar is the key and weak site in the rock bearing structure, and its instability causes the sinking displacement of the roof. Furthermore, the roof falling induces the shear failure area on the sidewall. The process of surrounding rock instability can be divided into four stages: elastic-plastic deformation, stable transition, unstable failure, and quadratic stability.