基于基质吸力的粘性路基土动回弹模量预估模型研究

Research on prediction model of dynamic resilient modulus of subgrade soil based on matric suction

为解决非饱和粘性路基土动回弹模量参数取值问题,采用滤纸法测定土样基质吸力,获取其土水特征曲线,并利用室内重复动三轴测试方法,进行了动态回弹模量测试,并探讨了动回弹模量的影响因素及其规律,进而在考虑含水量与基质吸力之间对应关系的基础上,集成创建了综合反映湿度状况(基质吸力)与应力状况(围压和循环偏应力)影响的粘性路基土新型动态回弹模量预估模型。研究结果表明,土水特征曲线Fredlund&Xing模型能够较好地关联非饱和粘性路基土基质吸力与湿度之间的相关关系;回弹模量测试值随围压、基质吸力和压实度的提高而增大,随循环偏应力和含水量的增大而减小。

Matric suctions of test specimens were surveyed by using the filter paper method, and parameters of soil-water characteristic curve （SWCC） equations were obtained by using regression analysis. For the sake of investigating factors which affect subgrade dynamic resilient modulus （MR） and their lows, a series of resilient modulus tests were carried out with repeated load triaxial tests on reconstituted cylindrical specimens. Based on the corresponding relationship between moisture content and matric suction, an innovative model to predict dynamic resilient modulus of subgrade based on matric suction was established, which integrate the influence of stress state （confining pressure and circular deviator stress） and moisture condition （matric suction）. The experimental results indicate that values parameters of SWCC are distinct for each specimens, Ms values increases with the increasing confining pressure, matric suction and compaction degree, and the circular deviator stress and moisture content decrease. Comparing to silty soil, the dynamic resilient modulus of clay is more sensitive to stress state and moisture content.