摘要
根据炎热多雨地区轨道交通周边土体的实际工程状态,开展经历不同干湿循环过程的花岗岩残积土的共振柱试验,研究炎热多雨气候影响下残积土小应变下的刚度特性。结果表明,受反复干湿循环效应影响,在10^(-6)~10^(-4)小应变范围内,残积土G_(max)随干湿循环次数n的衰变规律与常应变下黏性土强度特性衰减规律有较大差异,最大衰减出现在干湿循环中期;经历多次循环后,小围压下残积土的G–γ关系曲线出现直线下降和骤降阶段;利用Martin–Davidenkov模型和经验关系能较好地反映G/G_(max)和D随γ的变化规律,发现不同干湿循环次数后,G/G_(max)–γ关系随围压增大逐渐出现"两极分化"现象。研究还从微观角度对残积土小应变刚度特性的干湿循环效应给与解释,说明炎热多雨气候下残积土刚度的力学行为是由于结构强度减损、微观结构重塑引起。研究可为轨道交通工程动力参数的选取,类似工程场地的设计、施工及抗震分析提供技术参考依据。
Based on the actual state of the soil along rail transit in hot and rainy area, the resonant column tests on the soil under wetting and drying circles are conducted to study the stiffness characteristics of residual soil at small strain under hot and rainy climate. The results show that the decay law of Gmax in small strain range of 10^-6-10^-4 of residual soil is quite different from the strength characteristic of clay in conventional strain range, and the maximum attenuation occurs in the metaphase of the process of wetting and drying circles. After multiple cycles, the G–γ curves of residual soil under low confining pressure exhibit the linear decrease tendency and sudden drawdown. The martin-Davidenkov model and the empirical relationship may reflect the relationship between γ and G/Gmax as well as D, after wetting and drying circles, polarization phenomenon of the relationship between G/Gmax and γ presents gradually with the increasing confining pressure. The wetting and drying circle effect of the stiffness characteristics of residual soil at small strain is explained based on the microscopic analysis, and the mechanical behavior of stiffness of residual soil in hot and rainy area results from the injury of the structural strength and microstructure remodeling. This study may provide technical reference for the selection of the dynamic parameters of the rail transit engineering, the design and construction of the similar engineering sites and the seismic analysis.
出处
《岩土工程学报》
EI
CAS
CSCD
北大核心
2017年第4期743-751,共9页
Chinese Journal of Geotechnical Engineering
基金
国家自然科学基金项目(41372314,11672320,41472292,41372291)
中国科学院科技服务网络计划项目(KFJ-EW-STS-122)
关键词
炎热多雨
残积土
小应变
干湿循环
剪切模量
阻尼比
hot and rainy climate
residual soil
small strain
wetting and drying cycle
dynamic shear modulus
damping ratio
