Abstract: To explore the deformation characteristics of the collapsibility of a loess soil in Xining City and its numerical simulation method are presented in this paper. The current simulation methods on the collapsibility of loess soils do not fully consider the variation of the degree of saturation and the collapsible strain in the process of the water saturation. To better reflect the characteristics of the collapsibility of loess soils, a numerical simulation of the collapsibility of the loess considering the variation is proposed. The onsite geological investigations on the land subsidence and ground subsidence hazard caused by the collapse of the loess soils in Xining City were performed. The laboratory test results on the collapsibility were also performed to obtain the collapsible strain characteristics of soil samples with a range of degree of saturation from of 40% to 100%. The collapsing strain characteristic curve was studied by using the moisture swelling module of the numerical simulation software ABAQUS material library. The results show that the method can effectively establish the numerical analysis model of the collapsible loess soils in Xining City. The simulation results are generally consistent with the actual observed conditions. It is verified that the established model and the method are effective and feasible.

Key words: Collapsibility, Degree of Saturation, Collapse Strain, Moisture Swelling, Simulation Method