Fluid–Solid Coupling Numerical Analysis of Pore Water Pressure and Settlement in Vacuum-Preloaded Soft Foundation Based on FLAC3D

There are few calculation methods for the design and construction of vacuum preloading to strengthen soft foundations. Based on FLAC3D, a model was established project Beijing–Shanghai high-speed railway. Through comparison measured values, following results were obtained: (1) The top surface reinforcement area sand drain can be regarded as load boundary, which realized by assigning node pore water pressure. (2) After 30 days action, settlement rate at each depth decreased significantly deformation gradually became stable. It is reasonable time 2–4 months. (3) negative pressure has different transmission times uneven distribution, makes consolidation degree soil same level uneven. this phenomenon will transformed into uniform phenomenon. (4) change under about days. that, depths tend have constant values. influence reach 16 m. These works make up deficiency methods.