【摘要】 以沈哈高速铁路沿线的粘质黄土为研究对象,进行了冻结过程中封闭系统下土体水分迁移试验,试验结果表明:试样中温度的变化是先快后慢,最终试样内部温度随深度的变化呈现出一个稳定的温度梯度分布;温度势对水分迁移的影响甚微,温度梯度是导致含水量梯度产生的一个重要诱导因素,当温度的变化致使土体发生冻结时,冻结区的液态水含量急剧减小,从而引起其基质势能的急剧降低,促使土中未冻水沿着温度降低的方向迁移。基于上述试验,通过建立二维温度场与水分场耦合效应模型,应用有限元数值方法对室内封闭系统下模型试件的温度场、水分场进行了数值模拟,计算值与实测值基本吻合,验证了水热耦合数值计算模型的正确性。该模型可用于模拟季节性冰冻地区路基土体中水分迁移的变化规律,为冻胀防治提供依据。更多还原

【Abstract】 A moisture migration test for unsaturated clayey loess along the SHERFPL is done to understand the water migration of soil under a closed system in freezing condition.The experimental data shows that the temperature decreases with the slope degrading and eventually reaches a stable temperature gradient.Temperature potential has little effect on soil’s moisture migration.The formation of the gradient of soil’s water content is mainly caused by temperature gradient.With temperature decreasing to the freezing temperature of soil,the unfrozen water content decreases quickly in frozen zone.Such decrease results in the great drop of matric potential,making unfrozen water migrate toward the lower temperature zone.Based on the model test,a coupled heat-fluid transport equation is built and simulated by a two-dimensional finite element model,from which the temperature and moisture field of the specimen under closed system are obtained.It is found that the obtained results are closely agreed with the experimental data.Therefore,the model is adapted to simulate the variations of temperature and moisture of subgrade soil during freezing process in seasonal frozen ground,which can provide the basis for inhibiting frost heave.更多还原