既有铁路路基下软岩隧道的CRD法施工技术

在具有不均匀动荷载的软弱围岩中修建浅埋大跨度隧道，保证其上部设备及结构的安全，是隧道施工中的一大难题。在新曲儿岔隧道中采用CRD法施工，成功穿越了既有铁路路基。为确保安全，施工前利用有限元软件进行了模拟分析，表明采用CRD法施工是可行的。施工过程中，采用了变形监测手段，监测结果表明，及时的初次支护是控制拱顶下沉的有效措施。

Construction Technology of Soft Rock Tunnel by CRD Method under the Bed of Existing Railway

When shallow large-span tunnel is constructed in weak surroundng rock under uneven dynamic load, the great problem in tunneling lies in guaranteeing the security of ground equipment and structure. In the construction of Xinqu'ercha tunnel, the CRD method was utilized successfully to tunnel under the existing railway bed. Before constructing, the simulated analysis had been done with the finite element software to ensure its safety, and the results indicates that it is feasible to adopt CRD method in the construction. In the process of tunneling, the means of deformation surveying and monitoring was adopted, and the monitoring results shows that it is effective to control the fall of roof by mans of timely primary support.