青藏粉质黏土冻融循环试验研究

Experimental Study of the Tibetan Silty Clay under Freeze-Thaw Cycles

以青藏公路沿线常遇到的青藏粉质黏土作为研究对象,在室内分别进行了1、2、3、4次冻融循环试验,分析了冻融前后试样的温度分布特征、水分分布特征、冻融位移变化特征.结果表明:多次冻融循环的冻结过程中,温度场分布更趋向均衡和平稳,0℃等温线和低温等温线趋向深部发展;多次冻融循环后,试样含水量可划分4个区域,第1区域为表层冰晶聚集高含水量区,第2区域为低温梯度含水量均衡区域,第3区域为冷锋面冰透镜冰层积聚高含水量区域,第4区域为高温低含水量区域;青藏粉质黏土首次冻结的冻胀位移量和相对冻融位移量都比较大,冻胀量可以达到几十毫米,冻胀率可达8.3%,伴随冻融次数增加,相对冻胀量和相对冻融量幅值逐渐减少.

The Tibetan silty clay along the Qinghai-Tibet Highway was taken as the study object.The distribution of temperature and water content and freeze-thaw displacement of the specimens after 1,2,3 and 4 freeze-thaw cycles were obtained and analyzed.It is found that after freeze-thaw cycles,the temperature fields of the specimens will be more stable and proportionate distribution,the 0 ℃ isotherm and subzero isotherm will be deeper.The water content profile of the specimens can be divided into four sections.The first section is the surface layer one of high water content with ice crystal accumulation.The second section is water content equilibrium one with low temperature gradient.The third section is high water content one with ice lens and ice layers.The fourth section is lower water content one at high temperature.For the first freeze-thaw cycle,there are large frost heaving displacement,even reaching dozens of millimeters,and large relative freeze-thaw displacement,even reaching 8.3%.As the freeze-thaw cycles increases,the frost heaving displacement and the relative freeze-thaw displacement will gradually drop off.