降饱和度处理可液化地基振动台模型试验研究

Shaking table tests on induced partial saturation by chemical reaction for liquefaction mitigation

为探究降饱和度法处理可液化地基的可行性,利用化学法生成气体(二氧化锰催化过氧化氢产生氧气)降低砂样饱和度,制备不同饱和度砂样并进行了室内小型振动台模拟试验,分析不同加速度幅值的正弦循环荷载作用下,初始饱和度对试样中超静孔隙水压力、表面沉降和加速度放大系数等的影响规律,并基于室内试验结果评价化学法降低饱和度处理可液化地基的效果.结果表明,振动荷载作用下,试样中超静孔隙水压力随着初始饱和度降低而降低,随着加速度的增加而增大;加速度幅值为0.15g的正弦循环荷载作用下,当初始饱和度降低5.8%,试样中超静孔隙水压力减小约50%.试样体应变随试样平均孔压比的降低而减小,且呈线性关系.初始循环荷载下,各工况加速度放大系数均小于1.0,试样的振动衰减效果明显;尽管随着振动次数增加,超静孔隙水压力增加,试样的振动衰减效果减弱,但试样饱和度越低振动衰减效果越强的规律不变.试验证明,化学法降低砂土饱和度法是一种有效的可液化地基处理方法,具有应用前景.

To explore the technical feasibility of induced partial saturation method for liquefaction mitigation,partially saturated sand samples were prepared using a chemical reaction method and tested under shaking table simulation tests.Under applied sinusoidal cyclic loading with different acceleration amplitude,influences of initial samples saturation on the excess pore water pressure,surface settlement and acceleration amplification factor were investigated.The liquefaction mitigation beneficial effect was evaluated.The results show that the excess pore pressure decreases obviously with the decline of degree of saturation and increases with the rising of acceleration amplitude.The excess pore pressure falls by 50% when the initial degree ofsaturation decreases by 5.8% under applied sinusoidal cyclic loading with acceleration amplitude of 0.15 g.The volumetric strains of the samples drop with the decreasing of average pore pressure ratio,and there is a linear relationship between them.The coefficients of acceleration amplification under initial cyclic of load are all less than 1.0.With the decrease of degree of saturation,the damping effect of sample becomes intense.Although the vibration damping effect weakens with the increasing of cyclic numbers and excess pore water pressure,the rule remains unchanged.The research demonstrates that induced partial saturation method can be used for a liquefaction mitigation measure,and has a good application prospect.