考虑饱和度变化的高速铁路非饱和路基固结分析

饱和度对非饱和土的固结特性有明显影响,研究饱和度对固结变形的影响规律,有助于科学预测高铁基础工后沉降。基于Fredlund双参数理论和已有的一维固结解析解,求得非饱和土的一维固结速率。在考虑饱和度和渗透系数关系的情况下,结合典型算例,分析饱和度对固结特性的影响。研究结果表明:超孔隙气压力、超孔隙水压力的开始消散时间以及土体的开始变形时间均随着饱和度的减小而后延;高饱和度条件下的超孔隙气压力和低饱和度条件下的超孔隙水压力的消散速率更小,且消散过程更长;不同饱和度条件下的土体固结曲线在中前期都表现出相同的变形规律,但饱和度越大,土体固结时间就越短。

Consolidation Analysis of Unsaturated Soil in High Speed Railway Subgrade Considering Variable Saturation

The degree of saturation has great influence on the consolidation characteristic of unsaturated soil. To study the post construction settlement law of unsaturated soil foundation of high-speed railway, Fredlund's two-parameter theory and the existing one-dimensional consolidation analytical solutions are used and one-dimensional consolidation rate is obtained. Considering the relationship between the saturation and permeability coefficient, a typical example is used to analyze the influence of saturation degree on consolidation characteristics. Results show that the initial dissipation time of excess pore gas pressure, excess pore water pressure and initial deformation time of soil are all delayed with the decrease of saturation. The dissipation rate of excess air pressure is smaller at a high saturation degree and the dissipation rate of excess pore water pressure is smaller at low saturation degree and the dissipation process is longer. The consolidation curves of soils under different saturation conditions show the same deformation law in the early and middle stages. The consolidation time of unsaturated soil decreases with the increase of saturation.