Experimental Research on the Combined-Method of Vacuum Well-Point Dewatering and Preloading

In order to improve soft clay subsoil effectively in practice, the vacuum well-point dewatering and preloading method was used to test in Songhuajiang River flood land. Based on the field data observed in practice and effective stress theory of K. Terzaghi, the mechanism of improving soft ground by the vacuum well-point dewatering and preloading and the change of effective stress and effective reinforcement depth were studied. The experiment results showed that pore water pressure decreased quickly in sand drain but slowly in soil. Decrease of groundwater lever had great influence on preloading effectiveness. The effect of water closing was harmful to soil consolidation. With vacuum well-point dewatering and preloading, not only consolidation degree and speed increased but also the stability of side slope and the soil were improved. It is concluded that using vacuum well-point dewatering and preloading would speed up consolidation in the bank area of Songhuajiang River and similar areas.