冻土融沉系数的评价方法

融沉系数是估算冻土融化后沉降量的重要参数指标。融沉系数与冻土中的含冰量和干容重有关，含冰量大则冻土融化后的沉降量大，因此融沉系数大，在饱和状态，干容重较大的冻土，融沉系数较小，基于冻土融沉试验结果分析，建议引入界限孔隙率以此界定过大的冰含量完全用于沉降。将融沉分为3个状态来分析：非饱和、饱和以及过饱和(超过界限孔隙率状态)，给出的3个状态下的融沉系数计算方法与实验测试结果对比，具有较好的预报结果，从而使得融沉系数更容易评价。

The Evaluation of Thawing-Settlement Coefficient of Frozen Soils

Thawing-settlement coefficient is an important parameter for engineering design to estimate the thawing strain of frozen soils, which is related with soil type, water content and dry density. The coefficient increases with water content. In unsaturated state, the greater the dry density is, the larger the thawing-settlement coefficient is. But in saturated state, it decreases with increasing dry density. Based on the analyses of experiment results, the porosity in liquid limit state is suggested as a limit porosity to divide the water contribution degree for settlement deformation during freezing. When the porosity of frozen soil is greater than the limit porosity and the water fully fills the pore of soil, the water in excess of water content at liquid limit, as free water flowing out during thawing, should be counted completely as settlement deformation. So in the calculation of thawing settlement coefficient, the three states should be considered distinctively: non-saturation, saturation and super-saturation in which the water content is more than liquid limit. Contact ratio is suggested to estimate the contribution of unsaturated water content to settlement, which is zero when the water content is zero and 1 when the water content is up to saturated water content. In this paper the calculated method of thawing-settlement coefficient is presented and it has good prediction result as compared with measurement.