岩石爆破开挖诱发振动的等效模拟方法

岩石爆破开挖过程中爆炸荷载的复杂性、岩石介质模型的多变性、本构方程的多样性、以及群孔爆 破模拟计算工作量巨大等诸多因素使得准确模拟爆破诱发的围岩振动存在较大的困难,鉴于此提出一种等 效数值模拟方法。根据爆破过程炮孔周围岩石破坏范围的空间分布特征,确定群孔起爆条件下爆炸荷载作用 的等效弹性边界;通过分析炸药起爆后炮孔空腔动力膨胀、岩体裂纹扩展、炮孔堵塞物运动以及爆生气体的逸 出,计算了等效边界上沿炮孔轴向变化的爆炸荷载。结合瀑布沟水电站1# 尾水隧洞爆破开挖监测,基于动力 有限元法运用该等效技术模拟了围岩的质点振动速度。数值模拟与现场实测数据的对比表明该等效模拟技 术用于岩石爆破开挖围岩响应的计算是合适的。计算结果同时还显示,等效边界邻近岩体力学参数的选取对 计算结果有重要影响。

An equivalent simulation method for blasting vibration of surrounding rock

To overcome the difficulties in simulating accurately the blasting vibration of surrounding rock,an equivalent simulation method was presented.The equivalent elastic boundary subjected to the blasting load was developed for multiple boreholes according to the spatial character of rock damage around boreholes.Blasting loads on the equivalent boundary varying along the borehole axis was calculated theoretically through analyzing the expansion of borehole volume,the development of cracks,the movement of stemming and the outburst of detonation gases.Combined with the blasting excavation of the No.1 tailrace tunnel in Pubugou Hydropower Station,particle vibration velocities in the surrounding rock were simulated by employing this equivalent method based on the dynamic finite element method.The comparison between the simulation results and the monitoring data indicates that this equivalent simulation method is applicable to calculating the response of surrounding rock during blasting excavation;and that the selection of mechanical parameters of the rock near the equivalent elastic boundary has a significant impact on calculation results.