应变历史对黏土剪切模量和阻尼比的影响  

Effects of Vibration History on Modulus and Damping of Clay

作　　者：熊伟[1] 尚守平[2] 王海东[2] 周方圆[3] 李光辉 

机构地区：[1]中南大学土木建筑学院,长沙410075 [2]湖南大学土木工程学院,长沙410082 [3]名古屋大学土木工程系,日本爱知县名古屋4648601 [4]湖北襄阳市交通规划设计院,湖北襄阳430071

出　　处：《土木建筑与环境工程》2011年第1期71-76,共6页Journal of Civil,Architectural & Environment Engineering

基　　金：国家自然科学基金(50578062;50808078);国家科技支撑计划子课题(2006BAJ03A10-06);高等学校博士点基金(20070532090);湖南省自然科学基金(08JJ4016);湖南省科技计划重点项目(06sk4057)

摘　　要：在50 kPa1、00 kPa、300 kPa和500 kPa固结压力下,对16个土样进行高循环次数剪切试验以测定应变历史对正常固结黏土动力特性影响。实验结果表明:在排水固结阶段随着固结时间推移,剪切模量曲线上升而阻尼比曲线下降,剪切模量变化因固结压力增大更明显,25 h后两者变化趋于稳定;等幅值应变控制循环加载时,动剪模量和阻尼比在振动50周期内变化明显,之后变化趋缓,其中阻尼比随循环周数呈双曲线型变化。试验中发现明确应变历史门槛标志,其中阻尼比受其影响比动剪模量更明显,这对评估应变历史对土动力特性影响具有重要意义,值得进一步深入研究。Aiming at evaluating the effects of vibration history on dynamic characteristics of normally consolidated clay,a series of multi-cycled cyclic shear tests were conducted on 16 soil samples under consolidation pressure of 50 kPa,100 kPa,300 kPa and 500 kPa respectively.The experimental results reveal that,on the stage of drainage and consolidation,with the development of duration shear modulus curve ascends while damping curve descends;this trend became significant as consolidation pressure increased.The variation tends to be stable in 25 hours.When subjected to cyclic loading controlled by constant strain amplitude,both the modulus and damping of soil samples change significantly during the first 50 cycles,and then the differences become moderate afterwards,in which the damping curve acts in hyperbolical type.It is also found that there exists a clear sign of pre-straining that affects damping more significantly than modulus.

关 键 词：应变历史 动剪模量 阻尼比 循环单剪 门槛应变 

分 类 号：TU435[建筑科学—岩土工程]