时间效应对砂土小应变动力特性影响及其细观机制研究  

RESEARCH OF DYNAMIC PROPERTIES CHANGES AND MICROSCOPIC MECHANISM OF AGEING SAND

作　　者：陈光仔 蔡袁强[1,2] 王军[2] 董全杨[1] 

机构地区：[1]浙江大学软弱土与环境土工教育部重点实验室,浙江杭州310058 [2]温州大学建筑与土木工程学院,浙江温州325035

出　　处：《岩石力学与工程学报》2013年第S2期4215-4223,共9页Chinese Journal of Rock Mechanics and Engineering

基　　金：国家自然科学基金资助项目(51278383;51238009);国家重点基础研究发展计划(973)项目(2011CB411907)

摘　　要：采用英国GDS公司生产的共振柱(RCA)测试系统,对福建标准砂进行11组不同条件的时间效应试验,研究砂土小应变剪切模量和阻尼比随时间的变化情况,并运用颗粒滑移和接触力均一化理论对测试结果的细观机制进行解释。试验结果表明福建标准砂小应变剪切模量随时间逐渐增大,阻尼比随时间逐渐减小;同时研究发现相对密实度、应力历史和黏粒含量对砂土时间效应影响显著:在围压35 kPa时,松砂的时间效应大于密砂;当围压增加到150 kPa时,试验结果恰好相反:密砂的时间效应大于松砂。应力历史是影响砂土时间效应的重要因素:加卸载循环和超固结都会降低砂土的时间效应。在砂土试样中添加高岭土粉末能提高砂土的时间效应。Eleven tests of Fujian standard sand under different conditions using British GDS resonant column (RCA) system was conducted with the aim of researching the aging effects on small-strain shear modulus and damping ratio of sands and give explanations for the test results based on grain slip and contact force homogenization theory of granular materials. The experimental results show that,within a certain confining pressure,small-strain shear modulus gradually increases with time,and the damping ratio decrease gradually with time. At the same time,the research founds that the relative density,stress history and fines contents significantly effect the aging of sand. Under the confining pressure of 35 kPa,time effects of loose sand is greater than dense sand,however,when the confining pressure increase to 150 kPa,time effects of loose sand is less than dense sand. Stress history is one of the important factors affecting time effects of sand:unloading-reloading cycles and overconsolidation both can reduce the growth rate of small-strain dynamic shear modulus of sand. Aging rate of sand will be increased if dry kaoline powder was added to samples.

关 键 词：土力学 共振柱试验 时间效应 动剪切模量 阻尼比 

分 类 号：TU43[建筑科学—岩土工程]