Abstract:

 During the construction of Baozhen tunnel on YichangWanzhou railway, serious deformation of soft rocks with high ground stress, unconformity between excavationrevealed geological conditions and the designed geological conditions and severe support distortions happen. In order to ensure the successful tunneling through this section, countermeasures including installing flexible support before the installation of the rigid support, stress releasing before stress resisting, installing multilayer supports, improving the rigidness of the secondary lining and adopting supershort benches are taken, which brings the serious deformation of the surrounding rock mass under control. In order to better control the deformation, deformation predicting program is adopted. The comparison between the predicted values and the measured values shows that the software has a good reliability. By means of timely adjusting the support parameters according to the monitoring data, the tunneling successfully passes through the section.