黄土在地铁列车荷载作用下的临界动应力比及动应变发展模型的试验研究

Tentative study on the critical dynamic stress ratio and dynamic strain development model of loess under metro-induced loading

以黄土地区地铁项目为研究背景,利用20kN电液伺服控制动三轴试验机,对地铁列车荷载长期循环作用下不同类型黄土的动变形分别进行了试验研究,得到了不同类型黄土累积塑性变形的发展规律,提出了确定黄土临界动应力比的新方法,确定了不同类型黄土动应变发展的模型.研究结果表明：干型黄土的临界动应力比大于0.6,湿型黄土的临界动应力比为0.45-0.49,饱和型黄土则为0.22-0.24;拓展的Langmuir模型和经典Freundlich模型分别对于稳定型和破坏型黄土动变形发展的回归分析是有效的,反映了黄土在地铁列车荷载作用下的动变形特性.

Taking subway construction in loess area as research background,the experimental study on the dynamic strain of different types of loess under metro-induced long-term cyclic loading were carried out by 20kN electro-hydraulic servo dynamic triaxial apparatus,and the accumulated plastic deformation development law of different types of loess are obtained.Based on these,a new determination method of the loess critical dynamic stress ratio is brought forward,and the dynamic strain development model of different types of loess are determined.The results show： 1） the critical dynamic stress ratio of the dry type loess is greater than 0.6,and the critical dynamic stress ratio of wet type loess is 0.45-0.49,which for saturated loess is 0.22-0.24;2）the regression analysis on the stable and the destructive type of the dynamic strain of loess were implemented respectly by Extended Langmuir model.And the classical Freundlich model is effective,for reflecting the characteristics of the loess dynamic strain under metro-induced loading.