循环荷载下冻结兰州黄土变形性质的实验研究  

Experimental Study on Deformation Behaviors of Frozen Lanzhou Loess under Cyclic Loading

作　　者：罗飞[1] 赵淑萍[1] 马巍[1] 焦贵德[1,2] 

机构地区：[1]中国科学院寒区旱区环境与工程研究所冻土工程国家重点实验室,兰州730000 [2]兰州大学西部灾害与环境力学教育部重点实验室,兰州730000

出　　处：《地下空间与工程学报》2011年第6期1128-1133,共6页Chinese Journal of Underground Space and Engineering

基　　金：中国科学院西部行动计划(二期)项目(KZCX2-XB2-10);国家自然科学基金资助项目(40971046;40901039);中国科学院"西部之光"重点项目

摘　　要：对温度为-1℃的冻结兰州黄土在围压为0.6 MPa和不同动荷载振动频率条件下进行动三轴试验,试验采用分级加载,每一级荷载振动十次,加载波形为正弦波。实验结果表明:冻结兰州黄土的累积应变在整个加载过程中逐渐增大;当动荷载加载级数增加时,累积应变率逐渐变大。动应变幅随加载频率和振次的增加而减小;当频率小于或等于1 Hz时,动应变幅随加载级数的增加而增大;当频率大于1 Hz时,动应变幅随加载级数变化不大。随着加载级数的增加,滞回曲线的面积和密集程度越来越小,整体斜率和不闭合程度越来越大。用动模量来描述滞回曲线的整体倾斜程度。当频率小于或等于7 Hz时,动模量随加载级数的增加而增大;当频率大于7 Hz时,动模量随加载级数没有明显的规律。Under the confining pressure（0.6 MPa）and different vibratory frequencies of dynamic loads,a dynamic triaxial test is applied to measure dynamic modulus of frozen Lanzhou loess at-1 ℃.The dynamic loads,in the form of sine wave,are imposed on frozen soil and divided into several levels,each level consists of up to 10 cycles.The test results show that the accumulative strain in the whole process of loading increases gradually and the accumulative strain rate increases with increment of loading level.The dynamic strain amplitude decreases with increment of frequency or the number of vibrations.When the frequency is less than or equals to 1 Hz,the loading level increases with the dynamic strain amplitude;when the frequency exceeds 1 Hz,the dynamic strain amplitude changes little.With increase of loading level increment,the size and intensity of hysteresis loops decrease and slope and open degree of hysteresis loops increase gradually.Dynamic modulus,which is adopted to describe tilted degree of hysteresis loops,increases with increment of frequency.When the frequency is less than or equals to 7 Hz,the dynamic modulus increases with increment of loading level;when the frequency exceeds 7 Hz,there is no evident regularity of dynamic modulus changing with loading level.

关 键 词：动荷载 累积应变 动应变幅 滞回曲线 动模量 

分 类 号：TU444[建筑科学—岩土工程]