基于时程分析的岩质高边坡开挖爆破动力稳定性计算方法

提出一种计算岩质高边坡爆破开挖情况下动力稳定性安全系数的时程分析方法。根据爆破振动峰值速度衰减规律和爆破振动速度或加速度时程曲线，可计算得到特定时刻作用在各条块上的爆破振动惯性力，并根据其相位确定惯性力作用方向，然后施加到各条块上。结合刚体极限平衡分析方法中的Sarma方法，即可求得对应于该时刻边坡的稳定性安全系数。以某一时间步长进行整个爆破过程的计算，可得到相应的爆破动力作用下的边坡动力稳定性安全系数时程曲线。该法综合考虑爆破振动的幅值衰减、频谱特性和相位角的变化，突破了拟静力法中用综合影响系数折减爆破荷载的局限性，得出的边坡爆破振动稳定性安全系数随时间的变化规律，可较好地反映边坡稳定性在爆破过程中的变化过程，为优化边坡爆破开挖设计提供依据。

TIME HISTORY ANALYSIS METHOD FOR EVALUATING DYNAMIC STABILITY OF HIGH ROCK SLOPE UNDER EXCAVATION BLASTING

A time history analysis method for calculating the dynamic stability safety factor of high rock slope under excavation blasting is proposed. Based on the attenuation characteristic of the peak vibration velocity, and the time history curve of vibration velocity or acceleration, the inertia forces acting on the slices at given time can be calculated. The inertia forces would be acted on the slices according to their phases. Combined with Sarma method of limit equilibrium analysis, the stability safety factor at given time can be obtained. Analyzing the whole blasting vibration process at a certain time step, then the time history curve of the dynamic stability safety factor of the slope under blasting vibration could be got. In the proposed method, the attenuation of amplitude, the property of frequency spectrum, and phase of blasting vibration are included. The limitation of the conversion about blasting load by using a general coefficient in pseudo-static method is overcame. The time history of the safety factor of rock slope under blasting vibration is obtained, which well reflects the variation of the slope stability during excavation blasting, and can be a reference for the improvement and optimization on blasting design.