The Study Of Pit Resilience Mechanism And Behavior Of Pile In Soft Region

With the development of social economic and urban underground space,foundation pit developed toward to large and ultra-deep direction.The rebound of soil in the foundation pit engieering had attracted more and more attention.The phenomenon appeared frequently that piles were subjected to tension fracture and plates cracked caused by the soil resilience.So it was of significance to study the laws of soil resilience.The main work of this thesis was as follows :1.The thesis introduced the applicability and superiority of the small strain model for numerical simulation of soil resilience in foundation pit engineering.The sensitivity of advanced parameter used in HSS to the soil resilience was studied,which can provide some guidance for parameter selection and adjustment in the future.2.The factors that affect the soil resilience were studied by different plaxis models.The results showed that there would be different soil resilience modes with the different pit width.The deformation modes of retaining structure had obvious effect on the soil resilience.The seepage increased deformation and changed the modes of soil resilience.3.The deformation modes of soil resilience were summed up as the three kinds: ideal soil resilience,elastic soil resilience and plastic soil resilience.The ideal soil resilience modes was the theoretical basis for estimating the magnitude of soil resilience.Compared to elastic soil resilience modes,the plastic soil resilience modes had deeper influence depth.4.Using PLAXIS 3D software and the Hardening Soil model with small-strain stiffness,three-dimensional finite element models were established to study mechanical character of pile.The model considering depth of pit,length of pile and parameters of contact surface were to study the laws of pile strain,pile–soil relative displacement and skin fraction.