Deformation characteristics of a foundation pit in soft clay subjected to traffic loading

At present, the deformation characteristics of foundation pits in soft clay subjected to cyclic loading caused by various heavy traffic flow rates are still ambiguous. In this study, the impact of traffic flow rate on the deformation characteristics of a foundation pit in soft clay and the underlying mechanism were examined by performing a case study in Shenzhen, China. First, triaxial tests on the soft clay from the deep excavation project were carried out. The strength and stiffness degradation trends of soft clay under different numbers of loading cycles were revealed. The degraded parameters were then adopted to analyze the deformation pattern of the foundation pit under different vehicle flow rates with the dynamic finite element method. Based on measured data, the empirical equations between the different traffic flow rates and deformation results are fitted and converted to derive the empirical equations for the prediction of foundation pit deformation under various traffic flow rates. Finally, the mechanisms controlling the strength and stiffness degradation of soft clay as well as the deformation mechanism of the foundation pit in soft clay were explored from both macroscopic and microscopic aspects. This study can provide a reference for the engineering design of foundation pits in soft clay, particularly in the Pearl River Estuary.