高饱和度土的一维连续方程及其固结分析

One-dimensional continuity equation and consolidation analysis of unsaturated soils with high degree of saturation

为了解决高饱和度土的连续性条件表述的复杂性并由此建立相应的固结方程,从质量守恒的角度,避免了非饱和土中气相体积难以确定的困难,建立了土体的一维连续方程。假设Terzaghi有效应力原理依然适用于高饱和度土,推导了一维固结方程。在Terzaghi一维固结的假设基础上,再假设固结过程中饱和度为常数,求解了解析解。然后分析了高饱和度土的固结特性。结果表明:1)高饱和度固结方程与Terzaghi的一维固结方程形式完全一致,但是固结系数不同;2)因初始瞬时变形,初期固结度与饱和土的差别较大,随后差值减小;当时间因子等于1时,高饱和度土的固结度与饱和土基本相同;3)高饱和度土的固结完成时间与相应饱和土相比较,要延长;饱和度越小,土体的压缩性越小,其固结完成时间比越大。

It is complicated to found continuity equation for unsaturated soil because of the uncertain volume of air phase. In order to solve this difficulty and to derive the consolidation equation for unsaturated soils with high degree of saturation, one-dimensional continuity equation of three-phase soil was created compactly in the principle of mass balance. Supposing Terzaghi＇s principle of effective stress was still applicable to this type of soils, one-dimensional consolidation equation was derived. On basis of Terzaghi＇s hypotheses and supposing that the degree of saturation was constant during consolidation, the analytical solution was presented. Then the consolidation characteristic of soils was analyzed. And It is shown： 1） the form of consolidation equation of soils with high degree of saturation is the same to Terzaghi＇s onedimensional equation, but the coefficient of consolidation is different. 2） Because of the instantaneous deformation, the degree of consolidation in early stage is much bigger than that of saturated soils, and subsequently the gap is reducing; when the time factor is 1.0, the degree of consolidation is almost equal to each other. 3） The time needed for soils with high degree of saturation to complete consolidation is extended comparing to the corresponding saturated soils; the smaller the degree of saturation is, or the more compressible the soils are, the bigger the ratio of time for completing consolidation is.