Construction Control Techonology For Large Deformation Of High Speed Railway Tunnel In Argillaceous Strata

With the development of the long, large and deep buried tunnel in transportation at present, argillaceous rocks have been encountered in the construction of many tunnel projects in the vast northwest and southwest region.Argillaceous rock is a common kind of soft rock, which has the general nature of soft rock and its own unique engineering characteristics.During the construction, it may occur greater deformation and lead to many issues, such as support deforming, collapse, construction delay and cost increasing. It also causes casualties and projects crapped. So it is very important to study the large deformation control of tunnel surrounding rock during the construction of argillaceous rocks tunnel.Based on the Xiaozhai tunnel of Yungui high speed railway,this paper analyzes the large deformation control method of argillaceous rocks tunnel by field test and numerical simulation and field feasibility study. The main research results are as follows:(1) Based on the monitoring data of the site construction, the variation law of the arching deformation and the horizontal convergence of the arch is obtained after the excavation of the argillaceous rocks tunnel, and the large deformation characteristics of the argillaceous rocks tunnel are summarized,namely the tunnel deformation occurred very early with its deformation rate very rapid and last for a long time;and the total deformation of large deformation with the excavation disturbance and periodically characteristics, increase or decrease its deformation mechanism of argillaceous rock disintegration hydrolysis,expansion, change of shape and rock strata caused by bending deformation.(2) In combination with the practical situation of Xiaozhai tunnel in argillaceous rock stratum, large deformation tunnel construction methods were analyzed: also, by using the finite element software FLAC3D,big arch foot steps method and a numerical simulation of the three-bench cut seven-step method and argillaceous rock tunnel supporting parameters in the use of construction parameters and different 3 steps of the mechanical response of the seven steps excavation when the surrounding rock of numerical analysis, the results show that the three-bench cut seven-step excavation method can effectively limit the large deformation of the tunnel built in argillaceous rock stratum , and reduce the excavation?the step length and increasing the stiffness at the beginning of all can effectively reduce the convergence deformation of the surrounding rock.(3) For the control method proposed in accordance with the test measures and the numerical results, the feasibility study is carried out in the field. After field test, the method is feasible and effective, and the large deformation of the mudstone tunnel can be effectively controlled.