| With the advancement of metro construction,the structure forms of metro stations and linking tunnels have much varied. The sizes of them become increasingly larger;Complicated geologies and existing buildings have beenrepeatedly encountered in the process of metro construction,so construction technologies has correspondingly gained much progress,and have been innovated,in which many new construction methods have been successfully implemented in situ. The cavern-pile method for shallow buried underground excavated tunnels is one of them. Combining the advantages of the traditional shallow buried underground and partial excavation method with the characteristic of reverse construction method,the cavern-pile method exhibits higher flexibility and wider adaptability. Successful application to many station jobsites of the Fu-Ba line of Beijing metro program shows that using the cavern-pile method in loose soft stratum for excavating shallow buried large section tunnels is practicable. Therefore it has broad prospect for application. And it is worth much promotion. But current theoretical analysis on the method is not adequate,its mechanism and constraints of application 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 FEM,establishes an analysis frame based on the characteristics of the cavern-pile method. The influences of tunnel span,height,overburden depth,and excavation sequence on the cavern-pile method are discussed by a careful interpretation of the modeling result. In addition,acomparison of surface settlement and engineering quantity of the cavern-pile method with those of the binocular excavation method,bench cut method and CD method are made in the paper. The research is meaningful in theory for further application and promoting the cavern-pile method.
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