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分别采用不同浓度的NaCl溶液对低塑性黏土进行饱和,然后进行压力板和蒸汽平衡法试验,获得整个吸力范围内的土-水特征曲线(SWCC)。分析不同浓度的孔隙溶液对SWCC的影响规律,结果表明:盐分对基质吸力的影响较小,对总吸力影响较大,这主要是因为盐溶液引起的渗透吸力所致。在蒸汽平衡法试验中,随着含水率的降低,孔隙浓度增大,渗透吸力增大。然而,基质吸力随着含水率的减小迅速增大,使得渗透吸力所占的比例逐渐减小。在非饱和土中,总吸力包括基质吸力和渗透吸力;基质吸力包括毛细部分和吸附部分,当土体中含水率较低时,主要是吸附效应在起作用;渗透吸力与溶液浓度有关。根据试验结果深入分析了吸附水膜和土颗粒之间的相互作用,得出由于溶质的存在对分子间吸附力的影响规律。根据表面化学原理,建立了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土-水特征曲线。
The low plasticity clay was saturated with different concentrations of NaCl solution, then the pressure plate and steam balance test were carried out to obtain the soil-water characteristic curve (SWCC) over the entire suction range. The effects of different concentrations of pore solution on SWCC were analyzed. The results showed that the effect of salt on matrix suction was small, which had a great effect on the total suction, mainly due to osmotic suction caused by salt solution. In the steam balance test, as the moisture content decreases, the pore concentration increases and the permeation suction increases. However, the matrix suction rapidly increases with the decrease of water content, so that the proportion of osmotic suction gradually decreases. In unsaturated soils, the total suction includes the matrix suction and the suction suction; the matrix suction includes the capillary part and the adsorption part. When the water content in the soil is low, the adsorption effect is mainly at work; and the suction suction is related to the solution concentration. Based on the experimental results, the interaction between the adsorbed water film and the soil particles is deeply analyzed, and the influence of solute on the adsorption force between molecules is obtained. According to the principle of surface chemistry, the relationship between the intermolecular force and the thickness of the adsorbed water film was established to describe the soil-water characteristic curve in the adsorbed state.