真空联合注气降水机理的数值分析

Numerical Analysis of Vacuum Drainage with Air Injection

真空降水方法广泛应用于软弱地基处理工程,积累经验丰富,但软弱地基往往渗透性较低,其降水效率难以满足工程施工的工期需求。为提高降水效率,在真空降水的同时,可对真空抽气位置以下的土体进行注气,在压力气体驱动下实现快速降水。通过对不同注气压力工况的渗流计算分析,结果表明,注气可显著提高真空降水效果;压力气体作用下,降水区域的渗流水力梯度大幅增加,且真空抽气附近的非饱和土范围明显缩减,利于周围水体快速转移。

Vacuum drainage is used widely in soft foundation treatment, and a lot of experience has been gained. However, this method hardly meets the timing requirement of construction when the infiltration capacity of a soft foundation is very low. When pressed air is injected into the soft foundation as vacuum drainage is being carried on, water in porous soils may be pushed out of the foundation through the pipes for vacuum drainage, which can obvi- ously improve the efficiency of vacuum drainage. Mechanism of this technique was simulated through a series of cases under different pressed air pressures. The simulation results show that the air injection can distinctly improve vacuum drainage, increase evidently the gradients of hydraulic head for seepage, reduce remarkably the range of unsaturated soils, and therefore transfer underground water much easilier.