循环荷载下胶凝砂砾石材料的滞后及阻尼效应

为探求胶凝砂砾石(CSG)材料在动荷载下的力学特性,通过大型动三轴仪进行了等幅循环加载试验,分析了CSG材料的非线性滞后特性和阻尼比的演化规律.结果表明:加卸载过程中阻尼效应的差异引起了应力-应变曲线的不同步,在加载阶段,应变相位可能超前于或滞后于应力相位,两者相位差与循环次数有关;卸载阶段的应变相位始终滞后于应力相位;整个循环过程始终存在残余变形,从而使滞回环表现为下部不闭合的新月形;随着循环次数的增加,应变相位滞后于应力相位的程度和残余变形均呈大—小—大的趋势.基于新月形滞回环不闭合的特点,根据能量原理讨论了阻尼比的计算方法和演化规律,发现阻尼比的大小取决于残余变形和滞回环面积的大小,演化曲线呈U形.

Hysteresis and Damping Effect of Cemented Sand and Gravel Material under Cyclic Loading

In order to investigate the dynamic mechanical characteristic of cemented sand and gravel(CSG) material, the hysteresis effect and the damping ratio evolution law were studied under equal amplitude cyclic loading by large dynamic triaxial test. The results show that the difference of damping effect during loading and unloading can result in the strain out of sync with the stress, the strain phase is lagging or leading the stress phase in loading, while lagging behind in unloading. There is residual deformation exist in every hysteresis loop during the whole loading process, the hysteresis loops are crescent shape and unclosed in the bottom; the lagging and the residual deformation change from big to small and then become larger with the cycle number. The computing method and the evolution law of damping ratio were studied based on the characteristic of hysteresis loop and the energy principle. It is found that the damping ratio greatly depends on the residual deformation and the area of the hysteresis loop, and the evolution curves show U shape.