Strengthening of Soft Clay Ground of Ningbo Airport Runway by Surcharge Precompression

Ningbo Airport is built on the soft clay ground firstly in China. It has a runway 3,000m in length and 45m in width. The thickness of soft clay is greater than 32m. The calculated consolidation settlement is 0.48m, far beyond the allowable limit. The soft clay ground is improved by wick drain and surcharge pre-compression. The airport has been put in servirce since July, 1990. Process and result of in situ test, ground improvement and settlement obsevation are discribed. Influences of smear and well resistance of wick drain on consolidation rate are discussed.