The composite support form for shallow excavation of depth H≤7 m has been suggested and widely used in recent years. Basing on the engineering practice

we adopt the elastoplastic model and use plane finite element method to analyze the effect of supporting parameters on the deformation behavior of excavation with composite supporting. The general principle of deformation behavior of different support methods is obtained. When the soil nails and piles are adopted simultaneous as composite support system

they will notably enhance the effect of the support; and the deformation behavior is different from that using soil nail merely

and the maximal displacement of the supporting system will move downwards closely to the bottom of foundation pit. And when the appropriate angle of the slop is used the composite support form will control the displacement of the side of foundation pit more effectively.