Time-dependent solution for ground settlement induced by excavation in soft clay

By comparing the theoretical and measured results, it is observed that the current methods need to be revised in predicting the ground settlements induced by excavations in soft clay with a significant creep effect. Using the Lame equation and three-parameter viscoelastic foundation model, a time-dependent semi-analytical solution is derived for the ground settlements induced by arbitrary wall deflections. The solution is implemented in two excavations in Hangzhou soft clay, in which the development rules of the ground settlements from the soil excavation to basement construction are analyzed. The results indicate that: (1) The soft soil creep induces the ground settlements independently of the extra wall deflections, leading to a higher ratio of the maximum ground settlement to the maximum wall deflection during soil excavation compared to an excavation in non-soft clay. Furthermore, it results in continuous ground settlements during basement construction. (2) The ground settlements induced by the soft soil creep increase with wall deflections, showing the concave settlement mode. (3) The ratio of the maximum ground settlement to the maximum wall deflection of deep excavations in soft clay is primarily influenced by the creep characteristics of soft soil and construction duration, which appear unaffected by the wall deflections.