隧道爆破开挖作用下洞口高边坡的动力响应

Dynamic Response of High Slope at Tunnel Entrance Under Action of Tunnel Blasting Excavation

惠州市四环路西坑东隧道洞口段为八级高边坡,本文采用显式动力分析方法研究了隧道内钻爆施工中爆破效应对洞口多级边坡振动特性的影响。结果表明:由于地层的反射与折射,爆破地震波由拱顶的双峰形态变为坡面处的单峰形态,且振动速度峰值由拱顶处的28.810 cm/s迅速降至坡面处的0.383 cm/s;中导洞断面起爆后,边仰坡最下层测点振动速度最大,洞口侧边坡、路堑边坡依次减小,说明距离越远振动衰减越迅速;仰坡坡面测点振动速度峰值依次为上台阶起爆>下台阶起爆>中导洞起爆>侧导洞起爆,故装药量是影响边坡稳定性的关键因素;振动速度峰值小于规范安全允许的质点振动速度。该工程洞口高边坡在隧道钻爆施工下是安全的。

There is an eight-level high slope at the entrance of Xikeng East Tunnel in Huizhou Fourth Ring Road.The influence of blasting effect on the vibration characteristics of the multi-level slope at the entrance of the tunnel was studied by explicit dynamic analysis method.The results show that due to the reflection and refraction of the stratum,the blasting seismic wave changes from the double-peak form of the vault to the single-peak form of the slope surface,and the peak value of the vibration velocity rapidly decreases from 28.810 cm/s at the vault to 0.383 cm/s at the slope surface.After the blasting of the middle pilot tunnel section,the vibration velocity of the lowest measuring point of the side and front slope is the largest,the side slope of the entrance and the cutting slope decrease in turn,which indicates that the vibration attenuation is faster as the distance increases.The peak value of vibration velocity of measuring points on the front slope is in the order of upper bench blasting>lower bench blasting>middle pilot blasting>side pilot blasting.Therefore,the charge quantity is the key factor affecting the slope stability,and the peak value of vibration velocity is less than the particle vibration velocity allowed by the specification.The high slope at the entrance of the project is safe under the drilling and blasting construction of the tunnel.