Filed test on 25,000 kN•m ultra high energy level dynamic consolidation on large thickness gravel foundation

Abstract

A new airport is under construction at somewhere in northern China. The airport is located on an artificial island which is filled with gravel. Because the foundation is filled at one time and the thickness exceeds 22m, it should be consolidated. The designer supposed to use dynamic compaction method. The dynamic compaction energy may exceeds 15,000kN•m which is called ultra high energy level dynamic consolidation. However, the research of ultra high energy level dynamic consolidation and engineering examples available for reference are very few. Therefore, field test is necessary before formal construction to determine the reinforcement energy level and reinforcement effect. A series of dynamic compaction field tests with different energy levels were carried out. In this paper, dynamic compaction field tests of 25,000kN•m were introduced. In the test, flat load test was carried out to determine the bearing capacity of reinforced foundation, and deep settlement monitoring, layered settlement monitoring, ultra-heavy dynamic penetration test and multi-channel transient surface wave test were carried out before and after the consolidation to reflect the dynamic compaction reinforcement effect. The field test result shows that after dynamic consolidation of 25,000kN•m, the characteristic value of foundation bearing capacity is much larger than 150kpa, which meets the design requirements. Deep settlement monitoring, layered settlement monitoring, ultra-heavy dynamic penetration test and multi-channel transient surface wave test all can reflect the dynamic compaction reinforcement effect, and the monitoring results are very similar. After dynamic consolidation of 25,000kN•m, the reinforcement effect is not obvious in the range of 4m on the surface layer of the foundation, but obvious in the range of 4m to 16m, and still exists at 22m depth.