黄土反压饱和法及其在动强度试验中的应用研究

在黄土动参数研究中,黄土的饱和度是极其重要的影响因素之一.黄土具有结构性和湿陷性,不容易达到较高饱和度,并且饱和时间不宜过久.饱和黄土动三轴试验中,黄土的饱和度及饱和时间会对实验结果产生重要影响.以美国MTS 810土动三轴试验机为实验平台,进行黄土反压饱和法实验.探究黄土饱和过程中孔隙水压力与孔隙水压力系数B值、B值与饱和度之间的关系.研究表明:运用反压饱和法,可以在2~3 h内使原状黄土达到极高的饱和度;试样饱和度达到80%~100%时,饱和度与孔压系数B值呈指数函数关系,B值达到0.85可以认为试样达到完全饱和;饱和度与抗剪强度之间存在线性关系,与达到破坏时的轴向应力峰值存在线性关系.

Research on Application of Loess Back Pressure Saturation Method in Dynamic Strength Test

Saturation is a significant influencing factor in the research of loess dynamic parameters. Loess has features of structure and collapsibility, so loess cannot be soaked in water for a long time. In addition, loess cannot reach a high saturation. In the dynamic triaxial test of saturated loess, saturation and soaking time have an enormous influence on the experimental results.Taking the MTS 810 dynamic triaxial testing machine as the testing platform, the test is carried out by using the back pressure saturation method. This paper explores the relationship among pore water pressure, coefficient of pore water pressure and saturation during the saturation process. The testing results show that undisturbed loess can reach high saturation with- in 2 ~ 3 hours by using the back pressure saturation method. When the saturation of the sample is between 80% ~ 100%, the saturation has exponential relationship with the coefficient of pore water pressure. When the coefficient reaches 0.85, the sample loess can be fully saturated. There is a linear relationship between saturation and shear strength. There is also a linear relationship between saturation and peak stress of triggering liquefaction.