基于断裂力学及随机有限元的隧道岩爆风险分析

Risk Analysis for Tunnel Rockburst Based on Fracture Mechanics and Stochastic FEM

国内外大多数的岩爆预测方法中,都是利用应力强度比进行岩爆预测,该理论未考虑工程中存在的大量不确定性。基于此,提出了岩爆发生的断裂力学模型,即认为岩爆是由平行于自由表面的裂纹扩展造成的,在外荷载作用下,这些微小张性裂纹发生断裂,逐渐扩展、相互连接,当达到一定程度后,形成一定形状的肉眼可见的宏观裂纹,最终导致岩石破坏。以岩爆的层裂板模型为基础,运用可靠度原理及随机有限元方法,建立了岩爆发生的概率风险模型。工程实例计算表明,基于断裂力学及随机有限元的岩爆分析模型,可以较好地反映工程实际,为类似工程提供参考。

Stress-strength ratio model is usually applied to rockburst prediction in China and abroad,but uncertainties in engineering are not taken into account in this method.A fracture mechanics model of rockburst mechanism is proposed in this paper.This model is based on the assumption that rockburst is caused by microcracks which parallel to the free surface.These microcracks will fracture,extend,and mutually connect under external load.Then visible macroscopic crack is formed and finally rockburst happens.Furthermore,a rockburst risk probability model is proposed using reliability theory and stochastic FEM method based on Lamination spallation buckling model.The model was applied to engineering project calculation and the result manifested its rationality.