真空预压法中渗流体力和压差面力联合作用机理浅析

从渗流问题的基本方程出发，导出了真空预压的固结解析解，认为在地基中存在负压边界引起的瞬时稳定渗流与固结渗流2种不同特性的渗流、瞬时稳定渗流体力使膜下地基竖向拉伸、侧向受压，接近纯剪切应力状态，体积压缩变形较小，难以有效地加固地基．柔性膜上压差面力产生的偏应力与渗流体力的偏应力方向相反，大致可以互相抵消，使地基处于接近球应力状态．因此，膜上压差是加固地基的主要荷载，对地基的固结特性和最终加固效果起着控制作用．

Mechanism of combined action of seepage force and surface pressure difference in vacuum-preloading method

According to the basic equation of seepage, consolidation analytical solution of the vacuum-preloading method is deduced. It is considered that there are two kinds of seepage in foundations, i.e. the consolidation seepage and instantaneous steady seepage due to the negative boundary pressure. The force of instantaneous steady seepage results in the vertical stretching of the foundation under geomembrane and the lateral compression, which make the foundation in the state of pure shear stress with small volumetric compressive deformation, thus, the foundation cannot be reinforced effectively. The deviatoric stress caused by surface pressure difference is in the opposite direction to that caused by the seepage force, and the counteraction of the stresses makes the foundation under the flexible membrane in the state of spherical stress. Therefore the surface pressure difference is the main load for reinforcement of foundations and the key factor that determines the consolidation character and final consolidation effect of foundations.