地铁列车行驶振动荷载作用下饱和泥炭土细观结构演化及变形特性研究

地铁列车行驶荷载作用下含有机质泥炭土累积变形特性的充分认知为控制泥炭土地基累积沉降治理措施的研究提供极其必要的理论基础。而目前对其累积变形特性的研究尚未系统展开。据此，本项目以昆明泥炭土为研究对象，从有机质含量和列车荷载改变泥炭土细观结构的角度出发，对泥炭土累积变形发展规律和机理进行了深入研究。首先利用模拟列车荷载作用的循环三轴和CT扫描试验，构造泥炭土细观结构演化方程并建立基于细观结构状态变量的回弹剪切模量、回弹体积模量、累积应变速率与累积方向经验模型。继而在经典弹塑性理论框架下，构建可以描述列车荷载作用下泥炭土细观结构变化引起的全应力空间的累积变形预测模型。最后提出了该模型在边值问题中的应用流程，并编制相应的计算程序。本研究对于阐明泥炭土累积变形发展机理及其在路基病害治理中的作用具有重要科学意义和应用价值，同时相关的技术理论可推广应用于泥炭土地区高速铁路、高速公路和民航机场等工程中。

The full recognition of the accumulative deformation characteristics of peat soil under long-term train load provides an extremely necessary theoretical basis for the study of controlling the accumulative settlement of peat soil foundation.Therefore, taking Kunming peat soil as the research object in this proposal, the development law and mechanism of accumulative deformation of peat soil from the perspective of organic content and train load changing peat soil microstructure will be studied. Firstly, the cyclic tri-axial tests of peat soil under train load, combined with CT scans, will be used to reveal the relationships between the state variables of meco-structure and the accumulative plastic strain of peat soil. Based on experimental evidence, the meso-structure evolution equation will be established. And the empirical models of the relationship between dynamic shear modulus, dynamic bulk modulus, accumulated strain rate and accumulated direction and meso-structure state variable are produced. Then a constitutive model which can describe the meso-structure change of peat soil under long-term train load will be presented. Lastly, a numerical strategy integrating the presented constitutive model is produced for the boundary value problem.This study has important scientific significance and application value to elucidate the development mechanism of accumulative deformation of peat soil and its role in roadbed disease control, and may be used in the construction of high speed railway, highway or airport in peat soil regions.