Study on Excavation Methods of Shallow Buried Tunnels in the Horizontal Soft Rock Area of Red Layer in Northeast Sichuan
The red soft rock in northeast Sichuan is a special type of rock and soil,and the shallow buried tunnel is prone to large deformation or even collapse of the surrounding rock during construction.In order to ensure the smooth progress of the construction of similar projects,relying on the Yulongshan Tunnel Project of HBNZQSG-4 Lot of the Nanchong to Bazhong section of the Hanzhong-Bazhong-Nanchong High-speed Railway,the excavation method and deformation failure mode of the typical red layer horizontal weak surrounding rock tunnel in the area were studied,and combined with the numerical simulation results,effective measures to control the deformation of the surrounding rock were proposed.Research results are as follows:the displacement of the red layer soft rock tunnel vault increases first,then decreases slightly,and finally stabilizes;the construction safety cannot be guaranteed by the full-section method excavation;the disturbance of the surrounding rock during the construction of the tunnel using the step method is relatively large,but the step method excavation has the effect of unloading,which is conducive to alleviating the excessive stress concentration and simultaneously limiting the deformation of the surrounding rock and reducing the stress of the anchor rod.
railway tunnelred bed horizontal soft rockdeformation characteristicsstep methodfull face excavation methodcontrol measures
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