边坡爆破开挖对邻近已有洞室影响研究

INFLUENCE RESEARCH OF SLOPE BLASTING EXCAVATION ON ADJACENT EXISTED TUNNEL

边坡爆破施工振动对邻近已有洞室的影响及其控制是工程中的关键技术问题。新建边坡在与已有洞室间距比较小的情况下进行爆破开挖,爆破开挖产生的爆破波会危及已有洞室围岩和衬砌结构的安全与稳定性。结合锦屏一级水电站左岸坝肩边坡施工爆破对洞室影响的分析课题,应用动力有限元数值模拟,研究不同的边坡与已有洞室间距、岩体阻尼比、最大单响药量情况下边坡爆破振动对洞室围岩和衬砌结构的影响问题。根据洞壁质点振动速度允许值与洞室衬砌在边坡爆破振动波作用下的动拉应力值,考虑不同阻尼比,得出不同围岩级别下,不同边坡与洞室间距的最大单响药量控制:III类岩体边坡,坡面距已有洞室20,50 m时,边坡开挖爆破最大单响药量分别控制在100和300 kg以内;IV类岩体边坡,坡面距已有洞室20,50 m时,边坡开挖爆破最大单响药量分别控制在150和450 kg以内,研究结果为实际工程的施工和设计提供参考和依据。

The effect of slope blasting vibration on an adjacent existed tunnel and its control are key problems of tunnel project.Since the new slope is close to existing tunnel,the seismic wave induced by blasting endangers the safety and stability of the surrounding rock and the lining of existing tunnel.For a different distance between slope and tunnel,a different rock mass damping ratio,how much safety explosive quantity for single blasting in project is in urgent need of solution.On the basis of the simulation with the dynamic finite element method（FEM）,the effects of slope blasting vibration on the surrounding rock and lining structure of adjacent existed tunnel in different distances between slope and tunnel,damping ratio,safety explosive quantity for single blasting are studied,combining with influence of slope blasting on tunnel analysis issue on Jinping I hydropower station left bank project construction.According to the tunnel wall permitted vibration velocity and lining dynamic tensile stress caused by slope blasting vibration wave,obtain maximum explosive quantity of slope blasting constructions considering different damping ratios under different distances between slope and tunnel and different rock types： grade III rock mass,when distance between tunnel and slope equal to 20 and 50 m,the explosive quantity should be controlled in 100 and 300 kg respectively;grade IV rock mass,when distance between tunnel and slope equal to 20 and 50 m,the explosive quantity should be controlled in 150 and 450 kg respectively,and the research results provide the reference and basis to construction and design of the actual project.