Layer-wise Summation Method for Nonlinear Settlements of Ground Foundation Considering Disturbance Effect

Abstract

For the ground foundation influenced by the construction disturbance, the disturbance factor functions taking the shear strength and relative density as the disturbed parameters, respectively, were proposed based on the disturbed state concept. By using this function, a modified Duncan-Chang model considering the influence of disturbance was developed to provide a reference for the settlements prediction of ground foundation. Firstly, considering the stress state of ground soil, the analytical model for ground soil was established by idealizing the ground settlement to be the summation of one part caused by additional hydrostatic pressure and the other part by additional deviatory stress. Secondly, considering the stress history of ground soil, the determination method for initial deformation modulus of ground soil at different depths was provided by using the step-loading analysis method. Based on the Hooke’s law and modified Duncan-Chang model, the models to evaluate the settlement of ground foundation caused by additional hydrostatic pressure and of that by additional deviatory stress were then developed, respectively, by using the step-loading analysis method. The determination method for deformation modulus of ground soil was also given considering the additional stress effect. Finally, the proposed method was applied to a practical project case, and the corresponding settlement analysis was carried out. The results show that the proposed method has superiority and feasibility in the aspects of reflecting disturbance degree, stress state and stress history. The calculated results agree well with the prediction rule of settlement.

Keywords: foundation settlement,  step-loading,  disturbance,  stress state,  stress history effects