高饱和度土的压缩和固结特性及其应用

Compressibility and consolidation of unsaturated soils with high degree of saturation and its application

高饱和度土往往存在于湖海地区的含气泡沉积物以及工程中高含水率的压实土。试验表明高饱和度土中气相主要以封闭气泡形式存于孔隙水中,并随水一起流动。假设高饱和度土为具有可压缩流体的两相土,考虑水气混合物的压缩性,推导出不排水条件下土体压缩公式,并建立高饱和度土的排水固结方程,获得一维简化解析解。在此基础上,深入分析了荷载作用下高饱和度土的孔压系数、三轴试验的反压饱和过程与围压饱和过程、以及一维情况下高饱和度土的排水固结特性,重点讨论它与饱和土的区别。最后还对影响高饱和度土压缩和固结特性的主要参数进行了分析。

Unsaturated soils with high degree of saturation （St） are usually found in the gas-contained sediments of lakes and coasts as well as in the compacted soils with high water content. In this type of unsaturated soils, the air phase generally exists in the form of occluded bubbles within the pore water and moved with the pore water. It was assumed that the unsaturated soil with high Sr was a two-phase soil with a compressible fluid （i.e., mixture of water and air bubbles）. On the basis of this assumption, a formula was derived to calculate the soil compression under an un-drained condition, and then a close-form solution was developed to calculate the one-dimensional consolidation of the unsaturated soil. The obtained formula and solution were used to analyze the pore pressure parameter, the saturation processes （by applying back pressure and cell pressure） and the one-dimensional consolidation process, and compared with the saturated soils in detail. In addition, the main parameters affecting the compressibility and consolidation of this soil were analyzed.