不同地应力下爆破振动效应分析

Analysis of Blasting Vibration Effects Under Different Ground Stress

为研究岩石在不同地应力下的爆破振动效应,选择经验证过的岩石本构,利用ANSYS/LS-DYNA隐式—显式序列求解方法,对不同侧压力系数下岩石爆破过程进行数值分析。分别构建了侧压力系数为0.1、0.5、1.0、2.0、4.0条件下的计算模型,数值模拟结果表明:初始地应力对爆破有较强的抑制作用,岩石破碎区受侧压力系数的影响较小,爆破裂纹优先向较大的地应力方向延伸;岩石质点振动速度峰值(PPV)到达时间不受侧压力系数的影响;当侧压力系数小于1.0时,水平方向的质点振动速度峰值大于竖直方向;当侧压力系数大于1.0时,竖直方向的质点振动速度峰值大于水平方向。

As the depth of mining,tunnel excavation,etc. continues to increase,high ground stresses appear in the interior of the rock mass. High ground stress will have a great impact on the blasting effect of rock mass. In order to study the blasting vibration effects on rock mass under different ground stresses,the finite element software ANSYS / LS-DYNA is applied to simulate the propagation of stress wave in rock mass under high ground stress. The influence of blasting on the surrounding rock mass under different ground stresses is analyzed,and the effects of different ground stresses on the blasting effect is finally obtained.A constitutive model of rock mass is selected and calibrated. Then applying implicit-explicit method,the dynamic explicit software ANSYS/LS-DYNA is used to model the blasting process of rock mass under different lateral pressure coefficients. Numerical models are built under condition that lateral pressure coefficients are 0.1,0.5,1.0,2.0 and 4.0,respectively. Numerical simulation results indicate that high ground stress inhibits the blasting effects of rock mass and resists the damage extension around the blast hole. The lateral pressure coefficient has less influence on the fracture zone of rock mass,but has a greater influence on the crack zone of rock mass. And cracks will extend to the direction of higher ground stress more easily. Before the peak vibration velocity reaches its peak point,the rising time of peak particle velocity(PPV)is not influenced by lateral pressure coefficients. PPV in horizontal direction is greater than that of vertical direction when the lateral pressure coefficient is less than 1.0,while PPV in vertical direction is greater than that of horizontal direction when the lateral pressure coefficient is more than 1.0. This research can not only be used to evaluate the stability of deep rock mass structure under blasting load,but also can correctly guide blasting operation in engineering practice. More importantly,applying numerical simulation to analyze rock mass damage under blasting load can provide a reference experience for the in-depth study of the damage mechanism of rock mass under high strain rate dynamic loads.