Application of the Dynamic Compaction Method for Ground Improvement of Collapsible Loess in Qinhai

The collapsibility of loess has a great influence on subgrade construction in Qinghai, China, so laboratory tests are utilized to evaluate the collapsibility influencing factors, which illustrates that the collapsibility of this region is not dominated by soluble salts but an alkaline environment, high porosity and a low water content. The in situ self-weight submerging test reveals the settlement regularities, with a maximum settlement of 22.4 cm, which suggests that the soil in the test region is self-weight collapsible loess. In consideration of the economy and applicability, dynamic compaction was chosen as the ground improvement method. The optimal number of drops (N) for an energy level of 1000 kN·m is 6, and for the energy levels of 1500 kN·m and 2000 kN·m, N is 8. Besides the maximum effective depth for 1000 kN·m is 5 – 6 m, and it is 6 – 7 m for 1500 kN·m and 2000 kN·m.