Stability Analysis of Unsaturated Soil Pit Under Vehicle Load

To investigate the effect of in-pit vehicle load on the stability of the pit against overturning, a long tunnel foundation pit project in Suzhou is used as a case. In-pit vehicle load effects are modelled using the improved equivalent soil thickness method. Through the utilization of the upper limit theory of limit analysis of finite soils and considering the spatial distribution of suction force in the matrix of unsaturated soils, a deduced method for calculating the stability coefficient of the unsaturated finite soil pit against overturning under vehicle load is established. The results indicate that in-pit vehicle load favours pit stability against overturning relative to conventional outside-pit vehicle load. The change in pit stability is more significant when the soil rupture angle is corrected by using the improved equivalent soil thickness method. The increased suction in the unsaturated soil matrix contributes to the pit’s stability against overturning. When calculating the stability coefficient against overturning, the finite earth pressure theory proves to be more realistic than the classical earth pressure theory. The results of this study can provide a valuable reference for similar types of pits to prevent overturning.