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孔隙溶液的变化对土体的强度具有重要作用,为了分析孔隙溶液浓度的变化对黏土的有效强度及黏土颗粒微观结构的影响,基于应变控制式室内直剪仪和电镜扫描技术,对采用不同浓度Na Cl溶液饱和的重塑土样进行强度和微观试验研究。试验结果表明孔隙溶液浓度的变化对土体黏聚力有很大影响,随着Na Cl溶液浓度的增加,黏聚力呈现降低趋势,当Na Cl孔隙溶液达到0.1 mol/L时,黏聚力出现负值。黏聚力主要来源于颗粒间物理化学作用力对颗粒移动的阻碍作用,当黏土孔隙中的Na Cl溶液浓度增加时,颗粒间斥力减小,颗粒变的易于移动,黏聚力下降。同时由于土中真实孔隙水压力的存在,使得黏聚力呈现负值。另外,通过电镜扫描对土体微观结构的探测表明,用Na Cl溶液调拌的土样主要以凝聚结构为主,而用去离子水调拌的土样主要以集聚结构为主。
In order to analyze the effect of the change of pore solution concentration on the effective strength of clay and the microstructure of clay particles, the change of pore solution plays an important role in the strength of soil. Based on the strain-controlled indoor direct shear and electron microscope scanning, Na Cl solution saturated remodeling soil samples for strength and microscopic experimental study. The experimental results show that the change of pore solution concentration has a great influence on the cohesion of the soil. With the increase of NaCl concentration, the cohesion decreases. When NaCl pore solution reaches 0.1 mol / L, the cohesion A negative value appears. The cohesion mainly comes from the obstruction of the particle movement caused by the physico-chemical forces acting on the particles. When the concentration of NaCl solution in the clay pores increases, the repulsion between the particles decreases, the particles become easy to move and the cohesion decreases. At the same time, due to the existence of real pore water pressure in the soil, cohesion is negative. In addition, the scanning electron microscopy of the microstructure of the soil showed that the soil samples mixed with NaCl solution mainly dominated by the coagulation structure, while the deionized water mixing soil samples mainly in the aggregation structure.