节理岩体隧道塌方机理离散元研究

Study of Collapse Mechanism of Tunnels in Jointed Rock Mass by Distinct Element Method

为了研究节理岩体隧道塌方机理,依据节理统计与现场节理调查结果划分单元建立计算模型,采用离散单元法对隧道塌方运动全过程进行模拟,对塌方过程中块体行心处的位移、运动速度、加速度、应力的变化规律进行分析,总结出节理岩体隧道塌方的过程与特征.结果表明,节理岩体隧道塌方具有一定的规律性,隧道塌方的全过程可划分为5个阶段:裂隙启动扩展阶段、裂隙变速扩展阶段、裂隙加速扩展阶段、塌落阶段、塌落完成阶段.

A numerical model based on in-situ joint statistics was used to study the collapse mechanism of a tunnel in jointed rock mass. The collapse process was simulated using distinct element method and typical characteristics of the collapse were analysed. The displacement, velocity, acceleration and stress at each block＇s centroid were recorded during the simulation. The results show that the collapse of the tunnel has its regularity. Tunnel collapse can be divided into five stages： expansion of initial cracks; varying rate of crack expansion; accelerated expansion cracking; caving; and final collapse of the structure.