Influence of disturbance degree on the propped excavation stability in sandy soil in Shenyang, China

The stability of deep excavation is often investigated through numerical simulation. However, most constitutive models cannot take into account the influence of disturbance on soil response, especially for excavations in sandy soils. In this study, the conventional Duncan–Chang constitutive model is modified based on the data obtained from a series of triaxial consolidated drained tests on medium coarse sand with different relative densities, where all input parameters in the model are correlated with the changes in relative density due to disturbance. The modified hyperbolic model is then implemented in the general-purpose finite element code, ABAQUS. The efficiency of the proposed constitutive mode is demonstrated by comparing with the experimental data. Furthermore, a case study of a large-scale propped excavation for a subway station in Shenyang is analyzed through numerical calculations with the conventional Mohr–Coulomb model and the proposed hyperbolic model, and theoretical derivations based on the current technical code in China. It is found that the proposed approach can provide reasonable estimations compared with field measurements with a maximum error of 28% for maximum horizontal displacement of the solider pile and of 8% for maximum ground surface settlement, whereas the other techniques overestimate the behaviour of deep excavation significantly by more than 90%.