Analysis of deep dewatering foundation pit and retaining structure considering seepage – stress coupling

To investigate the deformation and stress behaviors of the pit and retaining structures under the coupled effects of excavation and dewatering in silty clay layers, this paper uses a deep excavation project of Xi'an Railway Station as a case study. The research methods employed include theoretical analysis and numerical simulation to perform a detailed analysis of the deep foundation pit and retaining structure affected by excavation and dewatering. The main conclusions are as follows: (1) Ground settlement, pit bottom uplift, and the deformation and stress of the retaining structure increase with greater excavation depth. Excavation and dewatering account for 58.3% and 41.7% of the total cumulative settlement, respectively. (2) The deformation of the foundation pit and retaining structure decreases with the increase in cohesion, internal friction angle, and elastic modulus, although the deformation distribution pattern remains unchanged. (3) Deformation indices decrease as the wall insertion ratio, wall thickness, support stiffness, and pre-axial force increase; however, the effectiveness of controlling foundation pit deformation gradually diminishes. (4) A ground settlement estimation formula based on conventional and skewed formulas is proposed.