Advances in Constructional Engineering

The prefabricated vertical drain (PVD) with vacuum preloading is widely used in soft soil treatment in coastal areas. The length and spacing of PVD are the key parameters affecting the reinforcement effect and construction costs. Based on a soft soil treatment project in coastal area, this paper puts forward the selection and optimal design method of the length and spacing of PVD. Firstly, the length of PVD is preliminarily determined according to the issued standard. Secondly, the influence of the length and spacing of PVD on the final settlement and settlement rate of the foundation is analyzed based on PLAXIS 2D numerical simulation, and the optimal design parameters are proposed. Finally, the reinforcement effect of PVD after design optimization is finally analyzed through the field measurement. The results show that a reasonable optimized length of the PVD is 10m~11m in this project. Compared with the original design, the length of PVD is reduced by 36.8%~39.6%, and the construction cost is saved by 30%. The reasonable spacing of the PVD is in the range of 0.8m~1.8m. With the increase of the spacing of the PVD, the consolidation rate decreases gradually, but final settlement values tend to be the same. The final settlement of the soft soil foundation after treatment is about 55.39cm, which shows a deviation of about 10.03% from the numerically calculated settlement of 61.57cm. The average shear strength from vane shear tests increases about 82.94% for the soft soil foundation after treatment. The results provide effective guidance for the optimal design of PVD in soft soil treatment.

Prefabricated vertical drain (PVD); Vacuum preloading; Soft soil; Soil treatment; Design optimization; Numerical analysis