考虑片理倾角的钻爆法隧道松动圈演变规律研究

Study on the Evolution of Loose Circle of Tunnel Constructed by Blasting Excavation Considering the Schistose Angles

为探究片岩隧道钻爆法开挖围岩松动圈演变规律,以牛栾村隧道为依托,运用地质雷达法对现场松动圈范围进行探测;采用数值仿真方法,模拟不同倾角片岩隧道爆破开挖过程,分析围岩松动圈的分布范围及演变规律。结果表明:受片理影响隧道松动圈并不总沿轮廓线对称分布,且水平与竖直方向不对称性的表现程度不同;由于内部片理构造与外部爆破开挖扰动的共同作用,片岩极易沿片理方向发生破坏,松动圈的形成也易沿片理方向发展;随着钻爆开挖的进行,松动范围呈非线性累积扩展状态,4次钻爆之后对初次产生的松动圈影响不再明显,隧道各部位累积程度不同;地质雷达的使用能够有效地实现隧道多次钻爆后围岩松动范围的探测。

In order to investigate the evolution law of the loose circle during blasting excavation of schist tunnel,the range of the loose circle of the Niuluan Village tunnel was detected by geological radar method.The numerical simulation method was used to simulate the blasting excavation for several times for different inclination of the schist tunnel model to analyze the distribution range and evolution law of the loose circle.The results show that:The loose circles are not always symmetrically distributed along the contour,and the horizontal and vertical asymmetries are different.Due to the joint action of internal schist structure and external blasting excavation disturbance,the schist is easily damaged along the schist direction,and the loose circles are also easily developed along the schist direction.With the blasting excavation,the loose circles show a non-linear cumulative expansion,and the loose circles are not easily developed after four blasting excavations.After four times of blasting,the influence on the initial loosening ring is no longer obvious,and the cumulative degree of different parts of the tunnel is different.The use of geological radar can effectively achieve the detection of the extent of loose circle after multiple blasting excavation.