大体积混凝土充填墙体高温破坏机理研究

混凝土充填墙体是沿空留巷技术实施的核心构筑物,为解决地下大体积混凝土充填墙体因高温产生温差裂缝等破坏状况的难题,综合运用现场调研、理论分析、实验室测试及数值模拟等多种研究方法,对巷旁充填墙体高温演化规律、多场耦合作用下的破坏机理进行系统研究。结果表明:充填材料高水化热、导热性差是导致温度裂缝产生的关键因素,温度应力超过墙体表面抗拉强度即产生温度裂缝,且出现表面裂缝后的大体积混凝土充填墙体对矿山压力的敏感度提高,在多应力场耦合作用下,墙体表面裂缝加速向深部扩展成贯穿裂缝,导致墙体呈多向裂隙破坏状态,充填墙体应在经受采动影响前加以强化控制。

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 multifield 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.