考虑主应力轴旋转的交通荷载下黏土变形特性试验研究  

Experimental Study on Deformation Characteristics of Clay under Traffic Load Considering Principal Stress Axis Rotation

作　　者：樊金甲 FAN Jin-jia(Hangzhou Transport Investment and Construction Management Group Co.,Ltd.,Hangzhou Zhejiang 310013,China)

机构地区：[1]杭州交通投资建设管理集团有限公司,浙江杭州310013

出　　处：《公路交通科技》2023年第2期36-43,共8页Journal of Highway and Transportation Research and Development

摘　　要：软黏土广泛分布于东南沿海地区,工程性质极差。为探讨考虑主应力轴连续旋转的复杂交通荷载应力路径作用下饱和软黏土的变形特征,对温州地区饱和原状软黏土进行了一系列不同加载条件下的动态空心圆柱扭剪试验。研究了动应力幅值和主应力轴旋转程度对饱和软黏土轴向应变、滞回曲线等力学特性的影响。利用此结果和应力应变滞回曲线,再结合前人给出的动骨干曲线模型,提出了考虑主应力轴连续旋转的交通荷载下的修正Hardin-Drnevich(H-D)动骨干曲线模型。结果表明:在交通荷载作用下,饱和软黏土轴向应变和回弹应变随着竖向循环应力比(CSR)和扭转动应力比的增大而呈现增长趋势,土体存在刚度软化现象;对比考虑主应力轴连续旋转和不考虑主应力轴连续旋转的交通荷载,发现前者会加剧试样变形,甚至导致试样提前破坏;试样在前期阶段轴向应变与回弹应变逐渐增大,在第1000次循环下轴向应变与回弹应变基本达到稳定值;该模型所得的预测值与试验值较吻合,与传统的H-D骨干曲线模型相比,该模型能很好体现土体在考虑主应力轴旋转的复杂交通荷载应力路径作用下的变形特征,更符合实际,弥补了骨干曲线在交通荷载研究领域的空白。Soft clays are widely distributed in the southeast coastal area of China with poor engineering properties.In order to investigate the deformation characteristics of saturated soft clay under complex traffic load stress path considering continuous rotation of principal stress axis,a series of dynamic hollow cylinder torsional shear tests on saturated undisturbed soft clay in Wenzhou area under different loading conditions are carried out.The influences of dynamic vertical stress amplitude and principal stress rotation degree on the mechanical properties of saturated soft clay such as axial strain and hysteresis curve are studied.Based on this result,the stress-strain hysteresis curves and the dynamic backbone curve model proposed by the former scholars,a modified Hardin-Drnevich(H-D)dynamic backbone curve model under traffic loading with principal stress axis rotation is proposed.The test result shows that(1)under traffic loading,the axial strain and resilient strain of saturated soft clay increase with the increasing vertical cyclic stress ratio(CSR)and torsional dynamic stress ratio,and the phenomenon of stiffness softening exists in soft clay;(2)comparing the traffic loads with and without continuous rotation of the principal stress axis,it is found that the former will aggravate the deformation of the sample and even lead to failure of the sample in advance;(3)the axial strain and resilient strain increase gradually in the early period,and reach the stable value basically at the 1000th cycle;(4)the predicted value obtained by this model is in good agreement with the test value,compared with the traditional H-D backbone curve model,this model can well reflect the deformation characteristics of the soft clay under complex traffic loading stress path with principal stress axis rotation,which is more in line with the reality,and fills the blank of backbone curve in the field of traffic load research.

关 键 词：道路工程 骨干曲线 动空心圆柱扭剪仪 软黏土 交通荷载 主应力轴旋转 

分 类 号：TU443[建筑科学—岩土工程]