电解减饱和法处理可液化地基的振动台试验研究

Model tests on liquefaction resistance of desaturation measures of electrolysis

减饱和法是近年来提出的一种可液化地基处理方法,其基本原理是通过工程措施减小饱和砂土地基中的饱和度,将饱和砂土地基变成不饱和的砂土地基,从而提高地基的抗液化强度,减轻地震时产生的液化震害。根据电解水的原理,采用新型可导电的塑料排水板为电极,开展了饱和砂土地基的电解试验,通过试验中产生气泡的宏观现象,确定了电解试验应采用的电极间距、电解电压、电极布置型式。基于室内振动台对电解减饱和法的抗液化效果进行了试验研究,考虑了电极在砂土地基中的竖向布置、水平布置和倾斜布置对地基抗液化效果的影响。结果表明,3种电极布置方案中水平电极布置方案在振动时产生的超孔压最小,抗液化效果最好。同时开展了电解后静置工况下的振动台试验,结果表明静置一段时间后,电解产生的减饱和作用仍然明显,但地基深部的气泡存在上移运动的趋势。在实际应用过程中,可以定期进行地基土体的电解作业,从而提高可液化地基的抗液化能力。

It has been proposed that liquefaction resistance of saturated sandy foundation can be improved through reducing its saturation degree. The electrolysis method is adopted to produce desaturated sand soils. By means of a conductive plastic drainage plate used as the electrodes, the electrolysis tests on water and saturated sand are conducted to determine the electrode spacing, electrolysis voltage and electrode arrangements. The gas bubble distributions of the saturated sandy foundation are analyzed to confirm the feasibility of electrolytic process. The effect of electrolytic procedure is experimentally validated based on the shaking table tests. According to different locations of the electrodes in sandy foundation, three different electrode arrangements, including vertical, horizontal and inclined modes, are compared. The results show that the horizontal one possesses the best liquefaction resistance since the generating excess pore pressure during the vibration is the lowest. Simultaneously, the tests on desaturated sand standing for a period of time after electrolysis are also carried out to investigate the effective time of desaturation effect. The results indicate that the desaturation effect still works under this condition. In engineering practice, the electrolysis of ground can be operated at regular intervals to keep the enhanced liquefaction resistance.