爆破作用下隧道裂隙围岩破裂范围

Blast-induced Fractured Zone of Fractured Rock-mass Tunnel

针对隧道松动圈形成过程的复杂性,以厦门翔安海底隧道钻爆法开挖为工程背景,利用断裂力学理论以及声波法和多点位移计测试方法,研究了爆破作用下隧道裂隙围岩开裂机理和破裂范围,并定量分析了爆破作用对隧道松动圈形成过程的影响。结果表明：由于方位角的不同,爆破作用导致裂隙围岩被拉断破坏、剪切破坏和拉剪破坏;以拉剪应力状态下的断裂准则和止裂条件可以确定裂隙围岩断裂破坏最大范围;爆破破裂范围占Ⅱ级围岩隧道松动圈大小的45%~65%;理论计算结果与实测结果基本一致,裂隙围岩爆破破裂机理为分析隧道松动圈形成过程提供了可靠依据。

With the complexity of forming tunnel loosing rock zone,the fracture mechanism and rupture range of fractured rock-mass tunnel under blasting effect were investigated with fracture mechanics theory and test methods（such as sonic method and multi-point displacement meter method）,taking Xiang＇an Subsea Tunnel in Xiamen as the research object.Furthermore,the influence of blasting on the forming of tunnel loosing rock zone was quantitatively analyzed.The results show that with the effect of explosive stress wave,fractured rock-mass emerges three failure modes under different azimuth angles,including tensile-shear failure,shear failure and tensile failure.The maximal blast-induced fracture rock-mass zone can be confirmed according to cracks＇arrest condition and fracture criterion under the condition of tensile-shear stress.The proportion of blast-induced fractured zone on the total loosing rock zone of gradeⅡrock mass is about 45%to 55%.The theoretical calculation result basically matches the result of field test,which provides a reliable basis for the analysis of forming tunnel loosing rock zone.