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一、前言 用排水压密法加固软土地基时,孔隙压力在软土中随总应力或八面体应力的变化规律以及对土体稳定、变形、强度的影响已有了不少研究成果。 按照有效应力原理,土体强度的增长和变形的产生都取决于有效应力的增加。对饱和软土来说,有效应力的变化是受超静水压力增消制约的。因而量测和研究孔隙水压力的变化规律就有十分重要的意义。近几年来重新发展起来的“真空排水预压法”是在不改变土中总应力的情况下,降低土中大气压力、形成负压对软基进行加固的。其实质也是增加土中的有效应力,而这种有效应力的增长是依赖于土中孔隙压力的降低。
I. INTRODUCTION When using the drainage compaction method to consolidate soft soil foundations, there have been many researches on the effect of pore pressure on the change law of total or octahedral stress in soft soil, and on the stability, deformation and strength of soil. According to the principle of effective stress, both the increase of soil strength and the generation of deformation depend on the increase of effective stress. For saturated soft soils, the change in effective stress is constrained by the increase or decrease in the excess hydrostatic pressure. Therefore, measuring and studying the change law of pore water pressure has very important significance. The “vacuum drainage preloading method” that has been redeveloped in recent years is to reduce the atmospheric pressure in the soil and form a negative pressure to reinforce the soft foundation without changing the total stress in the soil. The essence is also to increase the effective stress in the soil, and the increase of this effective stress is dependent on the reduction of the pore pressure in the soil.