考虑板状颗粒间相互作用的黏土强度时效性的微观解释  

Microscopic interpretation of time-dependent strength of clay considering plate-like particle interactions

作　　者：陈宝[1,2] 束庆霏 邓荣升 CHEN Bao;SHU Qing-fei;DENG Rong-sheng(College of Civil Engineering,Tongji University,Shanghai 200092,China;Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education,Tongji University,Shanghai 200092,China)

机构地区：[1]同济大学土木工程学院,上海200092 [2]同济大学岩土及地下工程教育部重点实验室,上海200092

出　　处：《岩土工程学报》2021年第2期271-280,共10页Chinese Journal of Geotechnical Engineering

基　　金：国家自然科学基金项目(41372270)。

摘　　要：为了探寻黏土强度时效性的微观机理,将时效强度与板状黏土颗粒搭接方式和相互作用势能联系起来,颗粒间的相互作用力使颗粒朝着势能较低的位置搭接,当颗粒间相互作用势能最低时,时效强度达到稳定值。提出了可考虑两板状颗粒间夹角θ和距离d影响的颗粒相互作用总势能公式,可用Zeta电位代替表面电位来计算势能,计算结果与实际情况相吻合。通过计算可知:①黏土时效强度与电解质浓度有很大关系,电解质浓度较低时(≤10^(-3)mol/L),两颗粒相互垂直时的总势能最低;电解质浓度较高时(≥10^(-1)mol/L),两颗粒相互平行时的总势能最低,时效强度几乎不变,甚至会减小;中间电解质浓度是过渡状态;②两黏土颗粒的稳定搭接方式主要是垂直和平行,两颗粒之间总会趋于向稳定搭接方式转化,这也是时效强度经历一定时间而达到稳定值的过程;③解释了黏土触变强度恢复的原因,即颗粒会一直趋于搭接强度最高的垂直稳定搭接。In order to explore its micro-mechanism,the time-dependent strength of clay is related to the overlapping mode and interaction potential of plate-like clay particles.The interaction force between the particles causes the particles to overlap toward a position with a lower potential energy.When the potential energy between the particles is the lowest,the time-dependent strength reaches a stable value.A total potential energy formula is proposed to consider the interaction between two adjacent plate-like particles with certain angleθand distance d,where the Zeta potential can be used instead of surface potential to calculate the potential energy.The calculated results of the total potential energy are consistent with the actual situations.It is shown:(1)The time-dependent strength of clay has a close relationship with the electrolyte content.When the electrolyte concentration is low(≤10^(-3) mol/L),the total potential energy is the lowest while the two adjacent particles are perpendicular.When the electrolyte concentration is high(≥10^(-1) mol/L),the total potential energy is the lowest while the two adjacent particles are parallel,and the time-dependent strength is almost unchanged,or even reduced.(2)The stable overlap of clay particles is mainly vertical and parallel.The two adjacent particles will always tend to be overlapped each other in one of these two ways,and so it takes some time for clay to reach a stable value of the time-dependent strength.(3)The reason for the restoration of thixotropic strength of general clay may be explained as that particles will always tend to overlap vertically,and this overlap way leads to the highest strength of clay.

关 键 词：黏土 板状颗粒 颗粒间相互作用势能 时效强度 微观机理 

分 类 号：TU43[建筑科学—岩土工程]