Field study on treatment of collapsible silt for high-fill airport project

The performance of the natural foundation soils in the original project site is the key factor affecting the deformation and stability of the high-fill foundation in airports. There is a layer of silt stratum with ultra-low water content and strong collapsibility, embedded in the shallow layer of the construction site of the north extension project of Urumqi Airport in Xinjiang, China, which may cause unavoidable collapsible subsidence to the high-fill foundation. In order to evaluate the feasibility and the effect of using the dynamic compaction method to treat the collapsibility of silt soil in this area, the field experiments with two different compaction energies are carried out before large-area construction of the high-fill backfill. The tests on physical and mechanical properties, plate load tests, immersion load tests, standard penetration tests and multi-channel transient surface wave tests are conducted before and after the dynamic compaction. In addition, the vibration and lateral displacement of the soils around the test area are tested during the dynamic compaction. Based on the test results, the effect of eliminating the collapsibility of silt and its mechanism are discussed, and the influences on the adjacent ground by the dynamic compaction method are also evaluated. Simultaneously, some phenomena found during the tests and their probable causes are analyzed, and thus the corresponding engineering measures are proposed, which can be used as a reference for similar high-fill projects with ultro-low water content.