宁夏饱和黄土的冻胀融沉特性

Frost Heaving and Thawing Settlement Characteristics of Saturated Loess in Ningxia

结合宁夏当地气候和黄土的区域特点,以初始干密度、冻融循环次数为因素,研究了宁夏饱和黄土在不同补水条件下的冻胀和融沉特性,分析作用规律和机理,建立了冻胀率、融陷系数与冻融循环次数和初始干密度的关系模型,为黄土地区的工程冻害防治提供理论和技术支撑。试验结果表明:宁夏饱和黄土的冻胀性大,有外界补水时冻胀率高达14.0%;无外界补水时冻胀率也在4.0%以上。冻胀率随初始干密度变化的规律与补水条件和冻融循环次数有关;有外界补水时,试样的融沉系数大,但随冻融循环次数的变化小,融沉系数随冻融循环次数的变化规律与初始干密度有关。冻融变形达到稳定时的冻融循环次数多,有外界补水时更多;建立的冻胀率、融沉系数关系模型预测结果准确,可信。

Combined with the regional characteristics of the local climate and loess in Ningxia,the frost heaving and thawing settlement characteristics of Ningxia saturated loess were studied by test with factors such as initial dry density,freeze-thaw cycles,and water conditions. Relationship models of frost heaving ratio and thawing settlement coefficient were established with analysis of action regulation and mechanism,which provides theoretical and technical support for the frost prevention of engineering in loess area. Results show that： The frost heave of Ningxia saturated loess is big,frost heaving ratio is up to 14. 0% under the condition of water supply,frost heaving ratio is also more than 4. 0% under the condition of no water supply. It is related to water conditions and freeze-thaw cycles that frost heaving changes with the initial dry density. Under the condition of water supply,the thawing settlement coefficient of sample is big,but the change with the freeze-thaw cycles is small,it is related to initial dry density that thawing settlement coefficient changes with freeze-thaw cycles. There are many cycles of freezing and thawing when freeze-thaw deformation is stable,more under the condition of water supply. The results are accurate and credible which are predicted with model of frost heaving ratio and thawing settlement coefficient.