水下真空预压过程中孔隙水压力变化规律研究

Variation law of pore water pressure in soil improved by underwater vacuum preloading method

孔隙水压力的量测和分析对研究水下真空预压法具有重要意义。在已经完成的水下真空预压现场试验中,把孔隙水压力做为主要研究对象进行了监测。结果显示孔隙水压力的变化受膜上水压和膜下负压的影响。水下真空预压期间土体中各点应力的改变等于加固前孔压与加固过程中孔压之差。膜上水压可以做为预压荷载。当膜上水压增大时,增加的水压使土体产生正的超静孔隙水压力,相当于堆载。水下真空预压过程中负超静孔压分布的不均匀使加固区内产生差异沉降和不均匀的强度增长。

The measurement and analysis of pore water pressure is significant for the studies on under watervacuum preloading method. In order to study the variation of pore water pressure, the full-scale field tests were performed. It was indicated that the variation of pore water pressure was influenced by water pressures on the sealing membrane and negative pressures in sand cushion. The variation of stress in soil was equal to the difference between the values of pore pressure before and during vacuum preloading, indicating that water pressures on the sealing membrane could act as preloading loads. When the depth of water on membrane increased, the positive pore pressure would be induced in soil which, and it similar to the surcharge load. The distribution of negative pore pressure in soil was not uniform, causing differential settlement and strength increase.