大直径泥水盾构开挖面泥浆渗透宏微观机理研究

The law of slurry infiltration in different types of soil in excavated ground is the key to maintain face stability of large slurry shield-driven tunnel in the complex and diverse tunneling environment. At present, the study of slurry infiltration mainly focuses on the mechanism of forming filter cake through laboratory experiment, and pays less attention to the coupling effect between slurry infiltration and soil in excavated ground. To this problem, based on the soil microscopic structure, the mechanism of slurry infiltration is studied by using laboratory experiment, theoretical analysis and numerical calculation. Firstly，with the slurry infiltration experiment, the permeability coefficient experiment and the scanning electron microscopy experiment, the pore fractal model is built to analyze the microscopic pore structure of soil and determine the type of infiltration according to the fractal theory, and the relationship between soil microscopic structure and slurry infiltration is established. Secondly, the calculation model of the coupling effect between slurry infiltration and soil is constructed considering microscopic pore structure of soil, seepage and diffusion of slurry concentration. The dynamic changes of stress field and seepage field caused by the migration of solid particles in slurry are calculated, and the influence of slurry infiltration on soil strength and slurry support pressure is analyzed. The mechanism of slurry infiltration is revealed with coupling macroscopic and microscopic aspect. This research will be able to provide the theoretical basis and method for the face stability of large slurry shield-driven tunnel as well as the optimization of construction parameters.

揭示泥浆在被开挖地层不同类型土体中的渗透规律是大直径泥水盾构在复杂多样的掘进环境中保持开挖面稳定的关键所在。目前，针对泥浆渗透的研究主要侧重于室内试验分析泥浆成膜的机理，而较少关注泥浆渗透与被开挖地层土体之间的耦合作用。针对此问题，本项目从土体微观结构入手，采用室内试验、理论分析和数值计算等方法研究泥浆渗透机理。首先，结合泥浆渗透试验、渗透系数试验、扫描电子显微镜试验，采用分形理论建立孔隙分形模型量化土体微观孔隙结构、判定渗透类型，搭建土体微观结构与泥浆渗透之间的联系；其次，创建考虑土体微观孔隙结构、渗流和泥浆浓度扩散的泥浆渗透与土体耦合作用的计算模型，解析泥浆固相颗粒迁移引起应力场、渗流场的动态变化规律，分析泥浆渗透对土体强度和泥浆支护压力的影响，从宏微观角度揭示泥浆渗透的机理。研究成果为大直径泥水盾构保持开挖面稳定、优化施工参数等提供理论依据和方法。

揭示泥浆在被开挖地层不同类型土体中的渗透规律是大直径泥水盾构在复杂多样的掘进环境中保持开挖面稳定的关键所在。目前，针对泥浆渗透的研究主要侧重于室内试验分析泥浆成膜的机理，而较少关注泥浆渗透与被开挖地层土体之间的耦合作用。针对此问题，本项目从土体微观结构入手，采用室内试验、理论分析和数值计算等方法研究泥浆渗透机理。开展了膨润土泥浆渗透试验、扫描电子显微镜 (SEM) 试验、渗透系数试验，研究了泥浆颗粒不同类型的填充渗滤规律及泥浆渗透与土体微观结构形态的相互影响。构建了考虑土体微观孔隙结构、渗流和泥浆浓度扩散的计算模型，揭示了泥浆渗透与被开挖地层土体之间的耦合作用。分析了泥浆渗透过程中泥浆固相颗粒的迁移，土体特征参数和地层中超孔隙水压力、有效应力的时空演化规律。研究成果为大直径泥水盾构保持开挖面稳定、优化盾构施工参数等提供理论依据。