Foundation Treatment Technology of Airfield in Shallow Karst Cavity

Based on the project of shallow karst cavity in Chenzhou Airport, Hunan Province, the effects of dynamic compaction of cushion and replacement pier of dynamic compaction on the treatment of shallow karst cavity are analyzed. Under the ramming energy of 4000 kN, the law of soil deformation and the change of physical and mechanical properties are studied. The standard and dynamic penetration test are carried out to verify the suitability of dynamic compaction. Results indicate that if the depth of foundation treatment is less than 2.0 m, it can be directly replaced; if the depth of foundation treatment is 2.0~8.0 m, it can be treated by cushion dynamic compaction method with point compaction twice and full compaction once, under the double control of 10~12 point compaction and final twice compaction with average settlement less than 5 cm; if the depth of foundation treatment is 8.0~10.0 m, it can be treated by replacement pier of dynamic compaction method to meet the requirement of foundation strength in karst airfield. it provides theoretical basis for foundation treatment engineering of airfield in shallow karst cavity area.