爆破开挖对岩体含水裂纹扩展的扰动机制

Disturbance mechanism of blasting excavation to aquiferous rock crack propagation

岩体裂纹的水力劈裂是岩体开裂渗漏甚至施工涌水的重要影响因素之一,也是岩土工程界的研究热点。从断裂力学角度分析了爆破开挖对岩体含水裂纹扩展的扰动作用,结果表明,爆破开挖扰动下,岩体含水裂纹的扩展,与爆炸应力波强度及其入射角、地应力的大小与方向、孔隙水压大小、裂纹的倾角及断裂韧度等因素相关;爆炸应力波的作用,相当于增大了岩体裂纹中的孔隙水压力,每1 cm/s的峰值振动速度相当于增大100 kPa的孔隙水压力,爆破振动速度越大,所产生的爆破扰动荷载越大;岩体开挖引起的岩体裂纹近区地应力及其孔隙水压力的变化,对裂纹的失稳与扩展具有较复杂的影响,可改变裂纹的失稳扩展模式。

The hydraulic fracturing of rock mass cracking is one of the important influencing factors that causes rock mass crackingand leakage and even construction water gushing, which is also the research hotspot in geotechnical engineering field. Thedisturbance effect on crack propagation of aquiferous rock cracking by blasting excavation is analyzed based on fracture mechanics;and the results show that, under disturbance of blasting excavation, the cracking propagation of aquiferous rock relates to the strengthand incident angle of blasting stress wave, the value and direction of ground stress, the value of pore water pressure, the crack dip,and the fracture toughness, etc. The effect of blasting stress wave equals to increasing the pore water pressure inside rock mass cracks,which means per 1 cm/s peak particle vibration velocity equals to increasing 0.1 MPa pore water pressure; and the larger the blastingvibration velocity is, the greater the blasting disturbance load will be. The change of ground stress and pore water pressure caused byrock mass excavation around rock mass cracks have complex influence on instability and propagation of cracks, which may changethe instability and propagation model of cracks.