Abstract：Deep foundation pit engineering is one of pop and difficult problems in rock soil engineering. How to effectively control deformation of foundation pit and make foundation pit engineering safe and economical is the task that people always probe. Deformation for retaining structure of foundation pit is the important factor for effect on the deformation of foundation pit. This paper simulates the stress path in the excavation of foundation pit by large numbers of true triaxial tests in allusion to the silty clay，which is representational in Wuhan area. The deformation properties of soil mass in the excavation of foundation pit have been founded out and the parameters of the Duncan-Zhang soil model have been gained，and nonlinear elastic model of retaining structure of deep foundation pit is established. At the same time，the foundation pit deformation of a piazza in Wuhan is calculated by using the methods of the plane strain finite element. The factors of design，construction and nature environment on effect of the deformation of timbering structures are studied. These factors include the rigidity of timbering structures，the digging width of foundation pit，the deformation modulus of soil mass，the inserted depth，the bracing location and the reinforcing of soils，space-time effect of pit excavation and water environment of foundation pit etc. The deformation of timbering structures in foundation pit excavation and the developing and changing rules of the settlement of surrounding stratum have been founded out. Some measurements，which offer the reference to the design and construction of deep foundation pit，to control the deformation of foundation pit have been put forward.
