高应变率下大理岩力学特性及损伤规律

Mechanical properties and damage evolution law of marble rock at high strain rate

受爆破开挖扰动影响,深部地下工程会处于“高地应力+动力扰动”的组合受力状态,了解此状态下的岩石力学性质和损伤规律对于地下工程施工具有重要的指导意义。以大红山铜矿某深部巷道为工程背景,对巷道内的大理岩试样开展了三维动静组合冲击试验,分析三维受力状态下大理岩的动态力学特性、能量分布特征以及损伤演化规律,结果表明:当轴压为14 MPa、围压为5 MPa、应变率为79.19~186.71 s^(-1)时,相对于单轴抗压强度,三维受力状态下的试样峰值应力可增大21.56%~135.42%;试样的能量吸收比与入射能呈线性相关,当能量吸收比为2.49 J/cm 3时,试样仅有少量裂纹贯通,未出现破碎;当能量吸收比为4.05 J/cm^(3)时,试样完全破碎;试样的损伤变量随应变呈指数增大,当超过峰值应变后,损伤变量快速增大。

Due to the disturbance of blasting excavation,deep underground works is likely to be affected by a combined stress of high in-situ stress and dynamic disturbance.Understanding of the mechanical properties and damage evolution laws of rock under this condition is of directive value to us in underground construction of projects.Taking a deep tunneling works in Dahongshan Copper Mine as the engineering reference,a three-dimensional and dynamic-static combined impact test was carried out on the marble rock samples from the tunnel.The dynamic mechanical properties,energy distribution characteristics and damage evolution law of marble rock under three-dimensional stress were studied.The results show that when the axial pressure was 14 MPa,the confining pressure was 5 MPa,and the strain rate was 79.19~186.71 s^(-1),the peak stress of the sample increased by 21.56%~135.42%compared to the uniaxial compressive strength.The absorption ratio was linearly associated with the incidence energy.When the energy absorption ratio was 2.49 J/cm^(3),only a small amount of cracks penetrated through the sample without any brea-kages.When the energy absorption ratio was 4.05 J/cm^(3),the sample was completely broken.The damage variable increased exponentially with the strain,and went up rapidly as the strain exceeded the peak.