孔隙溶液浓度的变化对黏土强度的影响  

Effects of pore solution concentrations on shear strength of clay

作　　者：于海浩[1,2] 韦昌富[1,2] 颜荣涛[1,2] 傅鑫晖[3] 马田田[4] 

机构地区：[1]广西建筑新能源与节能重点实验室,广西桂林541004 [2]桂林理工大学土木与建筑工程学院,广西桂林541004 [3]福建省建筑设计研究院,福建福州350001 [4]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,湖北武汉430071

出　　处：《岩土工程学报》2015年第3期564-569,共6页Chinese Journal of Geotechnical Engineering

基　　金：国家自然科学基金项目(11372078;51309055);广西自然科学基金创新研究团队项目(2012GXNSFGA060001);广西岩土力学与工程重点实验室项目(12-A-01-032)

摘　　要：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。Pore solutions play an important role in the shear strength of soils. A series of shearing and microcosmic tests are performed on the samples saturated with Na Cl solutions with different concentrations to investigate the effects of pore solution concentrations on the effective strength of clay. The experimental results show that the pore solution concentrations have strong effects on cohesion of samples. The cohesion decreases with the increase of pore solution concentrations. As the concentration approaches 0.1 mol/L, the cohesion decreases to below 0 k Pa. The cohesion depends on the block effect of physical and chemical forces between particles on the interparticle sliding. The repulsion decreases with the increase of the pore solution concentration which makes the interparticle sliding more easily. Due to the development of real pore pressure in the samples,the cohesion decreases to below 0 k Pa. The environmental scanning electron microscopy tests on the microstructures confirm that clays form flocculation in Na Cl solution and form aggregation in water.

关 键 词：黏土 直剪试验 化学–力学耦合作用 有效强度 孔隙水压力 

分 类 号：TU442[建筑科学—岩土工程]