真空堆载联合预压加固软基中孔隙水压力消散规律研究

Study on dissipation law of pore water pressure in strengthening soft foundation by vacuum-surcharge preloading

通过实测资料分析了真空堆载联合预压中不同深度的孔隙水压力、超孔隙水压力、相对超孔隙水压力随时间的变化规律,并对孔压变化的原因进行了微观解释。结果表明:(1)处理区外侧,孔压变化主要由地下水位下降引起,受真空影响较小;(2)在处理区内,孔压变化受真空负压、土体渗透性和堆载荷载的影响。真空作用下的渗流是孔压消散的主要方式,土体渗透性的强弱影响着孔压消散的速度,消散的孔压转化成有效应力,促使土颗粒移动,对孔隙水产生挤压,这使孔压消散呈脉动性特征。

Based on observational data of vacuum-surcharge preloading, the paper analyzed the laws of vary with time, which is pore water pressure, excess pore water pressure and relative excess pore water pressure in different depths, and the microcosmic reasons of the changes in the soil pore water pressure produced from the applied vacuum-surcharge pressure. The results indicated： （1）outside of the strengthened area, the changes of pore water pressure are mainly caused by the dropping of the water-table, which are affected less by vacuum degree. （2）inside of the strengthened area, the changes of pore water pressure are influenced by vacuum pressure, the permeability of soil and surcharge pressure. The seepage under the influence of vacuum pressure is the main form of pore water pressure dissipation, and the permeability of soil affects the speed of pore water pressure dissipation. Then the dissipating pore water pressure turns to the effective stress which makes soil grains move to press pore water. Finally, the dissipation of pore water shows pulsation characteristics.