深部岩体地应力瞬态卸载诱发振动效应的影响因素

Factors influencing vibration effects induced by in-situ stress transient unloading of deep rock mass

针对深埋隧洞爆破开挖振动控制,以瀑布沟水电站2~#引水隧洞爆破开挖为工程背景,讨论了地应力瞬态卸荷诱发振动特征及影响因素,并结合实测数据采用数值模拟的方法进行了验证分析。研究发现：中、高地应力条件下开挖面初始应力的瞬间释放诱发的振动是爆破开挖诱发振动的重要组成部分;当波阻抗一定时,开挖面初始应力动态卸荷诱发振动由地应力水平、开挖面初始应力、开挖面面积和振动衰减指数共同决定,动态卸荷诱发振动最强段发生在开挖面的初始应力和开挖面面积综合效应最大的位置;深埋隧洞爆破开挖振动的强度是由爆炸荷载和开挖面初始应力动态卸荷效应共同决定的,减小炮孔排距和进尺、采用较小洞径和分部开挖能有效降低地应力瞬态卸荷效应强度,控制深埋隧洞的爆破振动强度。

The blasting vibration control is one of the most significant factors during deep tunnel excavation. In this study, the characteristics and influencing factors of vibration induced by ground stress transient unloading were investigated by an integrated approach of field monitoring and numerical simulation of the diversion tunnel No.2 of Pubugou hydropower station. It is shown that the induced vibration by in-situ stress transient unloading of excavation surface plays an important role in the whole blasting excavation vibration under the medium and high in-situ stress conditions. When the wave impedance of rock is fixed, the induced vibration is controlled by the in-situ stress level, initial stress of excavation surface, excavation surface area and vibration attenuation index. The intensity of induced vibration is the highest at the station when the comprehensive effect of excavation surface in-situ stress and excavation surface area reaches the greatest. The blasting vibration intensity of deep tunnel is governed by the combined effect of explosion and in-situ stress transient unloading. The induced vibration can be effectively reduced by decreasing the row spacing of blast-holes and excavation footage, and adopting small holes diameter and partial excavation methods during deep tunnel excavation.