减饱和砂土缓倾场地的液化性状分析

减饱和法是一种通过减小砂土地基的饱和度，从而提高地基抗液化强度的新方法。基于减饱和砂土中流体模量同步更新的改进算法对减饱和砂土离心机振动台试验进行了数值分析，并与单一流体模量的简化算法进行了对比分析。结果表明：由于改进算法中考虑了因孔压变化引起的等效流体模量的变化，其计算结果更接近试验结果，而简化算法低估了减饱和砂土的孔压积累。基于改进算法开展了不同饱和度、倾斜角度的缓倾场地上液化变形的数值模拟研究，分析发现超孔隙水压力增长的速度及其峰值随着饱和度的增加而增大，饱和度从100%降低至96.4%，同一深度处的超孔压峰值降低约20%～65%，加速度响应的峰值也有明显的降低；沿地基深度0.75 m到9.00 m，侧向位移减少约20%～50%，表明饱和度的降低对抑制倾斜场地上可液化砂土层的侧向变形有显著效果，随着地基深度的减小，饱和度对于侧向位移的影响越来越明显。

Liquefaction characteristics analysis on gently tilting desaturated sandy ground

Desaturation is a mitigation method for sand liquefaction. Reducing saturation has been proposed to improve liquefaction resistance of saturated sandy foundation. Comparison of the centrifuge test numerical simulation was carried out, based on the modified single-phase fluid numerical method with simultaneous updating fluid modulus and the simplified method with fixed fluid modulus. The results show that the modified method is more reasonable because it considers the change of fluid modulus due to pore pressure change. The simplified method will underestimate the accumulation of pore pressure in the desaturated sand. Numerical simulation of liquefaction deformation on gently tilting desaturated sandy ground with different saturations and angles is carried out based on the modified single-phase fluid numerical method. The results show that the increasing velocity and peak value of excess pore pressure increase with the increase of saturation. The peak value of the excess pore pressure decreases by 20%-65%, and the peak value of acceleration response decreases significantly at the same depth with the saturation decreased from 100% to 96.4%. Along the foundation depth from 0.75 m to 9.00 m, lateral deformation decreases by about 20%-50%. It can conclude that the saturation reduction plays a positive role in reducing lateral deformation of liquefiable sandy foundation. The influence of saturation on lateral deformation is increasing evident with decrease of foundation depth.