【摘要】 滞回曲线的形态特征包括不闭合程度、宽窄程度、向应变轴的整体倾斜程度、密集程度和面积,采用残余应变p、滞回曲线的短轴与长轴之比、滞回曲线长轴的斜率k、相邻滞回曲线中心点之间的距离d和滞回曲线所围成的面积S五个参数定量表征滞回曲线的上述形态特征。对不同负温条件下的冻结青藏黏土进行动三轴试验,分析滞回曲线的形态特征,结果表明:同一级动荷载下,p,,k,d和S随振次的增加变化不大,因此,可以采用各参数的平均值来反映各级加载下滞回曲线的形态特征;随着动应变幅的增加,p,,d和S逐渐增大,k逐渐减小,即滞回曲线越来越不闭合、越来越宽、向应变轴整体越来越倾斜、越来越疏松、面积也越来越大,表明土的残余塑性应变、黏滞性、细观损伤程度和能量耗散越来越大,刚度越来越小。更多还原

【Abstract】 Morphological characteristics of hysteretic curves consist of closure,degree of width,degree of tilting to strain axis,intensive level and the area of the hysteretic curve.Residual strain p,the ratio of short axis length to long axis length,the gradient k of the long axis,the distance d between two center points of adjacent hysteretic curves,and the area S of the hysteretic curve are used to quantitatively measure morphological characteristics of hysteretic curves.Triaxial tests for different negative temperatures are carried out to study morphological characteristics of hysteretic curves of Qinghai-Tibet frozen clay.The test results show that: p,k,d and S change little with increasing cycle numbers under the same dynamic load condition;therefore,average values of p,k,d and S are adopted to measure morphological characteristics of hysteretic curves;p,d and S increase gradually,and k decreases gradually with increasing dynamic strain amplitude.In other words,closure decreases,degree of width increases,intensive level decreases,degree of tilting to strain axis increases and the area of the hysteretic curve increases with increasing dynamic strain amplitude,which indicate that residual plastic strain,viscosity,degree of microscopic damage and energy dissipation increase gradually,and stiffness decreases gradually.更多还原