Failure Mechanism of Mass Concrete Filling Wall Under High Temperature

The concrete filling wall is the core structure for the gob-side entry retaining technology. In order to solve the problem of high temperature cracks of mass concrete filling wall, methods such as field investigation, theoretical analysis, laboratory testing and numerical simulation are used to study the high temperature evolution law and the failure mechanism under coupling multi-field effect of the mass concrete filling wall. The results show that the key factors causing the temperature cracks are the high hydration heat and poor thermal conductivity of the filling materials. When the temperature stress exceeds the tensile strength of the wall, the temperature cracks appear. However, the stability of the filling wall is significantly affected by mining stress. Under the coupling effect of thermal stress and mining stress, the temperature cracks extend to the deep of the filling wall, and eventually develop into through cracks. Therefore, the filling wall should be strengthened before mining.