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爆破开挖是导致边坡节理岩体开裂甚至失稳的重要影响因素之一。基于断裂动力学理论,针对爆破开挖对边坡岩体裂纹失稳扩展的扰动作用进行研究,分析开挖扰动下地应力卸荷和爆炸应力波对裂纹尖端应力强度因子及其裂纹失稳扩展模式的影响。结果表明,爆炸应力波与地应力共同决定了边坡岩体裂纹的失稳扩展模式,初始地应力作用下边坡岩体裂纹的扩展模式主要为I–II压剪复合型;爆破开挖所产生的卸荷效应将改变初始地应力的状态,可使裂纹的扩展模式由I–II压剪复合型转变为I–II拉剪复合型,导致裂纹更容易失稳扩展,且卸荷程度越大,裂纹越容易失稳扩展;爆炸应力波的作用将增加岩体裂纹的失稳扩展风险。
Blasting and excavation is one of the important factors that lead to the cracking and even instability of rock joints in slope joints. Based on the theory of fracture dynamics, the perturbation effect of blasting excavation on the instability propagation of rock mass cracks is studied, and the stress intensity factor and the mode of crack instability of the crack tip under unloading and explosion stress wave are analyzed. Impact. The results show that the explosion stress wave and in-situ stress jointly determine the instability mode of crack propagation in slope rock mass. The main mode of crack propagation in slope rock mass is I-II pressure-shear composite type under the action of initial ground stress. The unloading effect will change the state of initial stress so that the mode of propagation of cracks can be changed from I-II shear-compression composite to I-II shear-shear composite, which makes the crack more easily destabilize and expand, and the unloading degree is greater , The crack is more prone to destabilize and expand. The effect of explosion stress wave will increase the risk of instability of rock crack propagation.