With the increasing demand for large and deep anchor projects in soft soil areas, issues related to settlement in circular foundation pits and damage to supporting structures have become significantly pronounced. The absence of pertinent design methods significantly impacts construction safety. Through on-site monitoring and statistical analysis, this study examines the spatiotemporal evolution of deformation in circular foundation pits, the deformation characteristics of retaining structures, and surface settlement features. Key design factors influencing the stability of circular foundation pits are explored. The research indicates that structural deformation and surface settlement are closely related over time and exhibit substantial spatial coordination. The deformation control capability of circular foundation pits is considerably stronger than that of square foundation pits, and it is less influenced by excavation depth. Diameter and soft soil thickness have a substantial impact on structural deformation and surface settlement. When the diameter is less than 40 m, the structural deformation remains below 0.1%. The study establishes an evaluation method for the deformation control of large and deep circular foundation pits in soft soil based on a significant amount of engineering monitoring data. It categorizes deformation control indicators for pit excavation based on different design factors, offering reliable theoretical support for relevant design professionals.

Liquefaction occurs when loose saturated sand loses its strength as a result of dynamic loading and begins to behave like a viscous fluid rather than a solid. This causes a huge reduction in effective stress, leading to loss of lives and property due to structure tilting, collapse, and foundation settlement. The 2001 Bhuj Earthquake triggered liquefaction in some areas of Gujarat and damaged buildings, bridges, ports, and dams. This study examines the behaviour of Kandla port's shallow foundation due to liquefiable soil during the 2001 Bhuj earthquake using finite element method by PLAXIS 3D software. Static and dynamic analyses of building founded on circular footing in terms of settlement, effective stress, and excess pore water pressure have been carried out. Also, vertical drain's liquefaction mitigation capability was investigated in this study. In the presence of buildings, vertical and horizontal deformation at the ground's surface and below the foundation were observed to be highest via dynamic analysis, with vertical deformation being smaller than horizontal deformation. This research revealed that dynamic settlements are higher than static settlement and, the vertical drains reduce excess pore water pressure and enhance effective stress. Dynamic analysis reveals that in the presence of buildings, vertical and horizontal deformation peaks at the ground's surface and beneath foundations, with vertical deformation smaller than horizontal. This study comprehensively explores earthquake-induced hazards, factors influencing liquefaction, and their impact on buildings. By examining the mechanisms through which earthquakes trigger hazards and liquefaction in structures, the research aims to enhance our ability to mitigate damage effectively.

The design of shallow foundations for wind turbines is typically governed by serviceability and fatigue limit states. To estimate the deformations of shallow foundations under working loads, existing design standards generally employ analytical uncoupled isotropic elastic solutions based on idealized soil conditions. However, many natural soil deposits exhibit some degree of stiffness anisotropy due to their deposition and complex stress history. This study has investigated coupled elastic stiffness coefficients for circular shallow foundations founded on cross-anisotropic soils under combined VHMT loadings (vertical, horizontal, moment and torsional) using finite element analysis. A three-parameter anisotropic soil model was applied to the problem. The study extensively explores the effects of soil stiffness non-homogeneity (i.e. linear increase of elastic modulus with depth) and foundation embedment on the foundation stiffness coefficients. Fitted expressions of these stiffness coefficients were also derived. In addition, a practical application using the proposed stiffness coefficients was presented to demonstrate the effects of soil stiffness anisotropy on the responses of a typical large wind turbine shallow foundation.