Effects of wall embedment on base heave failure arising from deep excavations in soft soils

摘要

There is an increasing demand for basement construction in congested areas and the successful execution of this relies heavily on mitigating ground movements. The three primary causes of ground movements include wall bending, wall displacement and base heave, thus parameters such as wall stiffness, embedment and excavation support systems can influence movements. Physical modelling was used to focus on preventing basal heave at the formation level and subsequently reduce movements adjacent the excavation. To investigate the significance of wall embedment in soft soils control measures were in place to isolate displacements typically observed from wall bending or inadequate prop stiffness. A 160 g centrifuge test was performed to observe ground movements during an excavation of a wall retaining 12 m soil and of 8.8 m embedment. Measurements from this experiment were used in the upper bound analysis of a fan mechanism and indicated that the factor of safety against basal heave was 1.25.