软弱破碎围岩大断面隧道台阶法施工几何参数优化分析

在软弱破碎围岩进行隧道开挖时，采用台阶法施工往往比cD法、CRD法等分多部开挖法要更加危险，容易产生大变形，塌方等事故，但由于它工期短、施工方便而常常为施工单位应用。依托人和场隧道，采用数值模拟的方法对台阶法上台阶开挖高度进行优化，以对台阶法进行适当优化。通过对比0．55H、0．60H、0．65H、0．70H、0．75H五种不同的开挖高度对隧道初衬和围岩的影响，得出在施工中采用0．65H的台阶高度是良好的，为工程施工提供参考。

Study of Bench Method＇s Geometric Parameters Optimization in Weak Broken Wall Rock and Large Cross-section Tunnel

In the soft rock tunnel excavation broken. Bench method is more dangerous than CD and CRD method, easy to produce the large deformation, landslides accident. But because it can shorten the construction period, so often be used by construction units. As all we know, the bench height plays an important role in the bench method optimization. This paper based on the railway tunnel, by means of the numerical simulation method to optimize the heights of up step in the bench method. By comparing the 0.55H, 0.60H ,0.65H, 0.70H, 0.75H five different height in the tunnel excavation of the influence of lining and rock, it is concluded that the 0.65H is the appropriate bench heights in the construction which is good for the engineering construction to provide the reference.