Inverse analysis of shallow foundation settlements on collapsible loess: Understanding the impact of varied soil mechanical properties during Wetting

Loess soil presents a collapsible behavior and suffers significant settlements due to wetting that can seriously affect the structures supported on it. The increase in water content produces a permanent change in loess soil microstructure and sudden volume reductions. In this work, a hydro-mechanical (H-M) model is presented to analyze the soil response and the behavior of strip foundations on loess soil using a 2D finite element model. Numerical models were calibrated, on one hand, from experimental data of double oedometer tests and soil water retention curve; and on the second hand, by retrofit analysis from the measurement of settlements in fullscale foundation prototypes over collapsible loess during controlled water pipe leakage. The settlements were studied by performing statistics, sensibility, and inverse analyses. Final settlements after 2 years of infiltration of water were computed using Monte Carlo simulations. The results show that the compression index at saturation is the most significant parameter controlling the behavior of collapsible loess. Optimum sets of parameters were achieved with inverse analysis, demonstrating the accuracy of the H-M model to predict collapse-induced settlements of shallow foundations.