Three-Dimensional Numerical Simulation And Analysis On Caven-PBA Method For One Shallow Metro Station In Shenyang

With the development of metro construction, its scale is growing, and the surrounding environment and the constraint factors are also increasingly harsh,so the scope of underground space is shrinking, and the structure forms of metro stations and linking tunnels have being much varied, and construction technologies has correspondingly gained much progress,and have been innovated,in whith many new construction methods have been sueeessfully implemented in situ.The Caven-PBA method for shallow buried underground exeavated is one of them. Combining the advantages of the traditional shallow buried underground and partial exeavation method with the characteristic of reverse construction method, the Cavern-PBA method exhibits higher flexibility and wider adaptability. The Caven-PBA method has been appled sueeessfully to many station jobsites in Beijing Metro Line Fu-Ba and Beijing Metro Line 10, and later,it's application has rapid progress in the construction design of many stations in Shenyang Metro Line 1 and 2, which proves that using the Caven-PBA method in loose soft stratum for excavating shallow buried large section tunnels is practicable. Therefore it has broad prospect for applieation. And it is worth much promotion. But curren theorectical analysis on the method is not adequate, and its mechanism and constraints of applieation are not yet fully understood, which may hinder the step of further use and promotion in the underground engineering.Considering the above reason, this paper, by the action-reaction model in the design theory of underground structure, and by FDM(Finite Difference Method), establishes an analysis frame of construction process based on the charaeteristies of the caven-PBA method. By analysis of the results, author points out the change laws of stratum displacement, and of ground stress, and of plasticity state of wall rock, and finnel stress state of metro construction. Finally, this paper concludes some features of Caven-PBA method, and tries to tell reader to how to shoose construction method, and what are payed attention to in struction designs and construction. The researeh is meaningful in theory for further application and promoting the Caven-PBA method.