循环荷载作用下NaCl溶液对黏土动力特性影响及微观机理分析

针对黏土易与水结合，孔隙溶液环境变化对黏土动力特性有较大影响的问题，使用GDS真/动三轴仪对黏土试样进行模拟交通循环荷载下的分级加载试验，研究不同浓度NaCl孔隙溶液、振动频率对土体应力-应变关系和动弹性模量的影响，分析骨干曲线及弹性模量的发展规律，并结合电镜扫描，分析NaCl溶液浓度和振动频率改变前后试样的孔隙分布规律，得到微观孔径与动力特性的关系。结果表明，随着NaCl溶液浓度和振动频率的升高，应力-应变曲线和动弹性模量曲线呈上移趋势；阻尼比-动应变曲线随振动频率的增加而上升，随NaCl溶液浓度的增加而下降；NaCl溶液浓度升高，水化反应产生的胶体增多，微填充作用可有效减少小孔隙，振动频率增加则使得片状颗粒间距被压缩，层状结构减少，土体更加密实，有效减少大孔隙。研究得出的含NaCl溶液黏土受孔隙溶液浓度与振动频率变化的影响规律，可为研究其他环境下黏土的强度变化提供参考。

Influence of NaCl solution on dynamic characteristics of clay under cyclic loading and microscopic mechanism analysis

Aiming at the problem that the change of the pore solution environment has a great influence on the dynamic characteristics of clay, graded loading tests were performed on clay samples under simulated traffic cyclic loads by using a GDS true/dynamic triaxial apparatus. The effects of different concentrations of NaCl pore solution and vibration frequency on the stress-strain relationship and dynamic elastic modulus of the soil were studied, and the development rules of the backbone curve and elastic modulus were analyzed. Combined with electron microscope scanning, the pore distribution law of samples before and after changing the NaCl solution concentration and vibration frequency was analyzed to obtain the relationship between micro-pore size and dynamic characteristics. The results show that with the increase of NaCl solution concentration and vibration frequency, the stress-strain curve and dynamic elastic modulus curve show an upward trend; the damping ratio-dynamic strain curve rises with the increase of vibration frequency and decreases with the increase of NaCl solution concentration; at higher NaCl solution concentration, the increase of colloid produced by the hydration reaction can effectively reduce small pores; increasing vibration frequency compresses the distance between flaky particles, reduces the layered structure and makes the soil more compact, effectively reducing large pores. The influence of pore solution and vibration frequency on clay with NaCl solution is obtained, which provides some reference for intensity change of clay under other environment.