多雨地区高速铁路填方路基性能状态与动力安定性分析

Under the situation of filled subgrade of high-speed railway in this project,in order to realize the evolution regularity of engineering property state and dynamic shakedown of subgrade bed soil and embankment soil under the condition of train loading and rainy environment, a series of dynamic triaxial tests of gravelly soils in various weting state and fine-grained soils in various wetting-drying cycle state for bed soils and embankment soils with different density are investigated, the changes of shear wave velocity and electrical resistivity are also timely measured during the period of testing, the change correlations of dynamic shear modulus, shear wave velocity and electrical resistivity of bed soils and embankment soils in various physical states with dynamic shear strain are obtained, in which the subgrade in-situ tests of ground penetrating radar, wave velocity,electrical resistivity,Rayleigh wave survey and its dipersion curves inversion are combined. Through the analysis of effectively physical parameter to characterize the subgrade performance state, the evaluation method of characterizion subgrade performance state is proposed, and the evolution charactersrics of subgrade strength and stiffness under the condition of train loading and rainy environment illustrated. On the basis of the above, the variation range of subgrade dynamic parameters with climate environment is put forward, a developed elasto-plastic constitutive model of subgrade soil is proposed by introducing the shakedown theory and concept of plastic response envelope subjected to cyclic loading，the cumulative plastic deformation of subgrade in various state under train vibation loading and its influence on long-term train running safety are analyzed by using the finite element method,it is helpful to promote the theoretical and technical support for scientific design,construction and runing safety of high-speed railway subgrade.

本项目以高速铁路填方路基为研究对象,以认知基床与路堤土体在列车荷载及多雨环境下的工程性能状态演化规律与动力安定性为目标，基于不同密度基床与路堤土体在不同湿化状态的粗粒土以及不同干湿循环状态细粒土动三轴试验，同步实时量测其波速与电阻率变化，结合路基现场地质雷达、波速、电阻率与瑞利波探测及其频散曲线反演，得出不同物理状态下基床与路堤土体的动剪切模量、波速与电阻率随动剪应变的变化关系式；通过分析表征路基所处状态性能的有效物理量，提出路基性能状态的度量方法，揭示在列车循环荷载与多雨环境作用下的路基强度及刚度演化特征；在此基础上，提出路基动力参数随气候环境的变化范围，通过引入安定性理论与循环荷载下塑性响应包络线概念，提出路基土弹塑性动本构关系，采用有限元方法分析处于不同状态的路基在列车荷载下的累积塑性变形及对列车长期安全营运的影响，为推进高速铁路路基的科学设计、施工与安全营运提供理论和技术支撑。

本项目针对花岗岩残积土填料及松散堆积体粗粒土填料的工程性能，研究了路基土体在列车荷载及多雨环境下的工程性能状态演化规律与动力安定性。分析论证了花岗岩残积土的原位力学特性与路用性能干湿循环效应，获得了干湿循环次数对其土-水特征曲线、孔隙大小分布曲线与强度参数的影响规律，建立了其电阻率与基质吸力的定量关系；基于动力学试验，揭示了花岗岩残积土在炎热多雨气候下小应变刚度特性衰变规律及动力变形特性，发现定向循环加载下残积土变形具有动力压密特性，累积塑性应变为稳定型曲线，呈现塑性安定行为与弹性安定行为，提出了一个高周循环荷载作用过程中土体塑性包络的弹塑性累积模型；空心扭剪试验结果表明，在列车荷载心形应力路径加载作用下土体变形明显增大，且其累积应变曲线在增湿饱和过程中由稳定型向发展型转变，结合高速铁路路基结构在列车荷载作用下的响应性状数值模拟，分析了不同路基本体含水率状态下路基内部的动应力及应变分布规律，提出了残积土作为路基本体填料的工程建议。研究了不同密度与含水率堆积体粗粒土的工程性能，论证了湿化对力学特性的影响模式，提出粗粒土的扩展亚塑性模型与参数辨识方法；分析了不同应力比与含水状态对其动力参数以及残余变形的影响，提出归一化动剪切模量比-动剪应变与阻尼比-动剪应变改进表达式以及粗粒土残余变形经验公式；探讨并建立了粗粒土动应力-动应变关系的塑性硬化循环动力模型，论证了颗粒级配对其力学性能的影响规律，并对循环荷载作用下路基粗粒土的累积变形特性与长期性能进行了分析。此外，还研究了红黏土工程性状的干湿循环效应与路基动力响应特征。上述研究, 深化了对多雨地区高速铁路填方路基性能状态变动特性的认知, 为推进高速铁路路基的科学设计、施工与安全营运提供了帮助。