Measurement and Simulation on Consolidation Behaviour of Soft Foundation Improved with Prefabricated Vertical Drains

Prefabricated vertical drains (PVDs) were used in accelerating the consolidation process of a soft soil foundation in the lower reach of the Yangtze river. Field monitoring was carried out during the embankment construction. The settlement, lateral deformation and pore pressure of the soft foundation were collected. The consolidation was also predicted with a coupled mechanical and hydraulic plane strain finite element model. The results indicate that the consolidation process of soft ground followed the loading steps. The PVDs can efficiently reduce the excess pore pressure in the soft ground and shorten the consolidation period. The pore pressure in the PVD reinforced zone is less than 20.0 kPa at the end of the construction in contrast to 52.0 kPa for unimproved foundation. The excellent drainage capacity of PVDs is useful in improving the shear strength of soft ground. Deformation form of the improved foundation is mainly the settlement and the lateral displacement at embankment toe is less than 9.0 cm. Stability analysis shows that the foundation is more stable during the construction with a factor of safety more than 1.20. Research results prove the feasibility of PVD technique in improving the soft ground in the lower reaches of the Yangtze river.