Research On Settlement Of Surrounding Ground Surface Induced By Deep Foundation Pit Excavation

With the flood of tower buildings in Suzhou,the deep foundation pit engineering develops fast.The study of problems presently existed in deep foundation pit in this area is few.The research of the theory and engineering experience for Suzhou has important practical significance.Based on the pit of Suzhou Oriental Gate,ground settlement induced by deep excavation is studied as the focus by the massive measured data and numerical ananysis.The primary researches and achievements are as follows:1 The computing theory and method of ground settlement induced by excavation and dewatering in foundation pit is firstly summarized.Then,based on Mohr-Coulomb model,the effect of dewatering on ground surface settlement is proved by FLAC finite difference program.2 Statistics and analysis of a large amount of monitoring data obtained from the foundation pit construction of Oriental Gate is conducted.The regulations of ground settlement,the deformation of underground pipelines,the water table change around the foundation pit as well as upright post settlement are summarized.And one relation between ground settlement around foundation pit and time,the distance away from the pit is established by regression analysis.3 Numerical analysis of surrounding ground surface settlement induced by excavation in deep foundation pit of Oriental Gate is made by FLAC.(1)By contrast analysis of the calculated result and monitoring data,it is too conservative to use the initial values of soil parameters according to the laboratory testing in the numerical computation of ground settlement around foundation pit.(2)Effects of elastic modulus,cohesion force,friction angle,permeability coefficient, coefficient of earth pressure,dilatancy angle and parameters of soil-structure interface on the ground settlement around foundation pit are analyzed.(3)According to the influence of soil parameters on ground settlement around foundation pit,dynamic variation for values of soil parameters in the process of dewatering and the property of soil in the engineering site of Oriental Gate ,an adjusting range of soil parameters has been proposed.Then,the adjustment of soil parameters in the site is implemented by back analysis method of parameters.The adjusting range of soil parameters can be provided as reference of deep foundation pit engineering in this area.In the end,the paper summarized the whole contents,and put forward the further contents that would be researched.