路堤下泥炭土地基的固结机理及沉降计算方法研究

Yunnan province is an important province in the One Road, One Belt strategy promotion process. At the same time, the construction quality of highway and railway infrastructure directly affects the portal image of Yunnan. The peat soil is widely distributed in Yunnan province, and the engineering problems caused by peat soil are especially prominent. But, at present, the study on consolidation mechanism and settlement calculation method of peat land is not mature. Then, based on the peaty soil in Yunnan and Xinjiang province, through the methods of thermogravimetric analysis and scanning electron microscopy, the change of the microstructure and the moisture content of various types of peat soil will be studied, and the mechanism of large and long duration settlement of peat soil will be explored. By changing the thickness of specimen, test temperature and pH of the water environment, the indoor uniaxial compression test control conditions, which can reflect the peat soil consolidation process will be studied. Then, through the uniaxial compression test of peat soil under different load levels, the change rule of coefficient of primary consolidation and secondary consolidation during different time, consolidation pressure, and the content of organic matter will be analyzed. Combine the indoor model test, theoretical analysis and long term monitoring results, the primary and secondary consolidation settlement law of peat land will be discussed, and a settlement calculation method of peat land in different pressure range will be proposed.

云南省作为我国“一带一路” 战略推进过程中的重要省份，其公路、铁路等基础设施的建设质量直接影响其门户形象。而云南省泥炭土分布广泛，因泥炭土引发的工程问题尤其突出。但目前对于泥炭土地基的固结机理及沉降计算方法的研究尚不成熟。鉴于此，本项目拟针对云南、新疆等地的泥炭土，通过热重分析法、电镜扫描法等，研究不同荷载等级下泥炭土微观结构的变化过程以及泥炭土中各种类型水分含量的变化规律，探讨泥炭土地基沉降量大、沉降持续时间长的机理；通过改变试样厚度、试验温度、环境水的酸碱度等，寻找能够反映现场泥炭土地基固结过程的室内单向固结试验控制条件，并完成不同荷载等级下泥炭土的单向固结试验，分析泥炭土主固结系数、次固结系数等随时间、固结压力、有机质含量等参数的变化规律；结合室内模型试验、理论分析及现场长期监测结果，探讨泥炭土地基的主、次固结沉降规律，提出不同压力范围内泥炭土地基的沉降计算方法。

云南省作为我国“一带一路”建设的节点性省份，其高速公路、高速铁路的建设质量关系到国家发展布局的实现速度，而在云贵高原大量存在的泥炭土严重影响着工程施工的进度以及质量，我国目前对于泥炭土地基的固结机理及沉降计算方法的研究尚不成熟。鉴于此，本研究以云南大丽高速公路为依托，以大理、昆明等地的泥炭土为主要试验材料，探索了适合泥炭土的单向固结试验条件，并在此基础上，分析了泥炭土固结系数、次固结系数以及渗透系数等参数的变化规律；通过分析其变形过程，提出了泥炭土固结变形的三个阶段及划分方法，同时，从成分和结构变化角度，分阶段研究了泥炭土的固结变形机理。最后，通过分析室内模型试验数据，在对比了其他研究人员的试验结果的基础上，提出了泥炭土地基沉降的三阶段分层总和法。本研究主要成果对深入认识泥炭土的工程性质、恰当选择泥炭土地基处治措施、控制工后沉降有着显著的指导性作用。