变孔隙条件下非饱和冻土渗透系数试验与分析

摘要

寒区土壤水文循环过程因冻土层的存在而复杂,冻土层中冰的存在使其水理性质变化引发许多特殊水文现象,在冻土水理性质研究过程中冻土渗透性研究是其中的关键问题之一.为了研究非饱和冻土合冰率和干密度对于非闭合孔隙度及其渗透性的影响,选取不同含冰率(2％、4％、6％、8％、10％、12％、14％、16％、18％、20％)、试样干密度(1.4×103 kg/m3、1.5×103 kg/m3、1.6×103 kg/m3)作为单因素变量,采用定水位达西试验方法分别进行冻土渗透系数测定试验,开展了非饱和冻土渗透系数测定试验研究.结果表明:非饱和冻土渗透系数及非闭合孔隙度随试样含冰率的增加而变小,随试样干密度增加而变小,变化范围为0.19-0.714及8.55-19.18m/d.当含冰率为20％、试样干密度为1.6×103 kg/m3时得到最小非饱和冻土渗透系数为8.55m/d,最小非闭合孔隙度为0.19.%Frozen soil permeability is one of the key issues in the process of frozen soil water properties research due to special hydrological phenomenon caused by the change of frozen soil water properties.In order to study the effect of ice content and dry density on non-closed porosity and permeability of unsaturated frozen soils,choose ice content (2％,4％,6％,8％,10％,12％,14％,16％,18％,20％) and dry sample density (1.4 × 103 kg/m3,1.5 × 103 kg/m3 and 1.6 × 103 kg/m3) as a single variable factor to measure frozen soil permeability coefficient.The water level test method was used to determine the permeability coefficient of frozen soil,and the experimental study on the permeability coefficient of unsaturated frozen soil was carried out.The results show that the permeability coefficient and the unclosed porosity of the unsaturated frozen soil are smaller with the increase of the ice content and dry sample density,and the range is 0.19-0.714 and 8.55-19.18 m/d.When the ice content is 20％ and the dry density of the sample is 1.6 × 103 kg/m3,the minimum unsaturated permafrost permeability coefficient is 8.55 m/d and the minimum unclosed porosity is 0.19.