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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。
According to the local climate and regional characteristics of loess in Ningxia, the initial dry density and the number of freeze-thaw cycles were used as factors to study the frost heave and thaw sinking characteristics of saturated loess in Ningxia under different recharge conditions. The law of action and mechanism were analyzed and the frost heaving Rate, the relationship between thawing coefficient and the number of freeze-thaw cycles and the initial dry density, provide theoretical and technical support for the prevention and treatment of engineering frost damage in the loess area. The experimental results show that the frozen expansiveness of saturated loess in Ningxia is large, frost heaving rate is as high as 14.0% with external replenishment, and frost heaving rate is also above 4.0% without external replenishment. The variation of frost heaving rate with initial dry density is related to the condition of water replenishment and the number of freeze-thaw cycles. When the external replenishment is applied, the sample has a large thawing and thawing coefficient but with a small change in the number of freeze-thaw cycles, The number of changes in the law and the initial dry density. The number of freeze-thaw cycles when the freeze-thaw deformation reaches a steady state is more, and there is more when there is external replenishment. The established prediction model of frost heave rate and thawing-thawing coefficient is accurate and credible.