巷旁砼墙体耦合破坏机理及控制对策研究

Study on Coupling Failure Mechanism and Control Measures of Concrete Wall along Roadway

巷旁砼充填墙体是确保深部沿空留巷稳定性的关键支护结构。为解决地下大体积砼充填墙体因高温产生温差裂缝进而引起墙体大面积破坏的难题,综合运用现场调研、理论分析、数值模拟及工业试验等多种研究方法,对巷旁充填墙体破坏的现状、墙体致裂因素、多场耦合作用下的破坏机理以及控制对策进行了系统研究。结果表明:墙体破坏需经过表面裂缝、裂缝扩展、裂缝贯通3个阶段,充填材料自身高水化热、外部环境导热性差,造成温度应力超过墙体表面抗拉强度进而产生墙体表面温度裂缝,温度应力与矿山压力的耦合作用是墙体由表面裂缝发展到完全破坏的关键诱因。基于此,设计出充填墙体内外同步降温方案,降低了温度裂缝产生的几率,减小了充填墙体恶化的可能性,保证了充填墙体的完整性和强度。

The concrete filling wall along roadway is the key supporting structure to ensure the stability of deep gob-side entry retaining technology.In order to solve the problem of large area destruction of mass concrete filling wall caused by cracks due to high temperature,methods such as field investigation,theoretical analysis,numerical simulation and industrial test were used to study the failure status,cracking factors,failure mechanism under multi-field coupling and the control measures of the concrete filling wall along roadway.The results showed that the failure of concrete filling wall will pass through three stages,including surface crack,crack propagation and crack penetration.Due to high hydration heat of filling material and poor thermal conductivity of external environment,the temperature stress will exceed tensile strength,and then,the surface temperature cracks will appear.The coupling effect of temperature stress and ground pressure was the key factor for the wall to develop from surface crack to complete failure.Therefore,a synchronous cooling scheme of filling wall inside and outside was designed,which can reduce the probability of temperature cracks,reduce the possibility of deterioration of the filling wall,and ensure the integrity and strength of the filling wall.