NaCl溶液对土体冻结特征影响的试验研究

发布时间：2018-03-31 11:44

本文选题：盐溶液　切入点：冻结特征曲线　出处：《岩土力学》2017年07期

【摘要】：冻结特征曲线(SFCC)是指冻土中温度和未冻水含量之间的关系,采用核磁共振系统和低温恒温冷浴获得了采用不同浓度Na Cl溶液饱和的黏土的冻结特征曲线。根据试验结果分析不同浓度的孔隙溶液对冻结特征的影响规律,结果表明:随着溶液浓度的增大,冻结特征曲线向上移动,也就是说在相同未冻水含量下,浓度越大,冻结温度越低。这主要是因为盐溶液引起了渗透势能,使得孔隙水中总势能降低,从而降低了孔隙水的冰点。在冻土中,孔隙水的冻结温度与能量状态有关,其中孔隙水的势能包括基质势能和渗透势能,而基质势能部分又分为毛细部分和吸附部分,渗透势能与孔隙溶液的浓度有关。当土体中未冻水含量较低时,主要是吸附效应在起作用。此时未冻水是以吸附膜的形式吸附在土颗粒的周围,将非饱和土的概念引入到冻土中,采用分子间作用力和吸附水膜厚度之间的关系,以描述处于吸附状态的冻结特征曲线。结合渗透势能来模拟不同浓度下的冻结特征曲线,与试验数据拟合结果较好。
[Abstract]:The freezing characteristic curve (SFCC) refers to the relationship between temperature and unfrozen water content in frozen soil. The freezing characteristic curves of clay saturated with different concentrations of NaCl solution were obtained by nuclear magnetic resonance (NMR) system and low temperature constant temperature cold bath. According to the experimental results, the effects of different concentrations of pore solutions on the freezing characteristics were analyzed. The results show that the freezing characteristic curve moves upward with the increase of solution concentration, that is, the higher the concentration of unfrozen water, the lower the freezing temperature, which is mainly due to the osmotic potential energy caused by salt solution. In frozen soil, the freezing temperature of pore water is related to the energy state, and the potential energy of pore water includes matrix potential energy and permeable potential energy. The potential energy of matrix is divided into capillary part and adsorption part. The osmotic potential energy is related to the concentration of pore solution. When the content of unfrozen water in soil is low, In this case, unfrozen water is adsorbed in the form of adsorption membrane around soil particles. The concept of unsaturated soil is introduced into frozen soil, and the relationship between intermolecular force and the thickness of adsorbed water film is adopted. The freezing characteristic curve in adsorption state is described, and the freezing characteristic curve at different concentration is simulated by osmotic potential energy, which fits well with the experimental data.
【作者单位】：桂林理工大学广西岩土力学与工程重点实验室;中国科学院武汉岩土力学研究所岩土力学与工程国家重点实验室;
【基金】：国家自然科学基金(No.11502276,11372078) 广西岩土力学与工程重点实验室资助课题(No.13-KF-01)~~
【分类号】：TU445

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