岩体三维粗糙裂隙网络非线性渗流及溶质运移特性研究

Since fracture provides the main path of the fluid flow and solute transport trough the rock masses, research on its flow property and solute transport characteristics plays an important foundation for underground engineering construction and environmental safety. Taking the three-dimensional rock fracture network as the object, and considering the fracture surface roughness and aperture anisotropy, this project will reveal the mechanism of nonlinear flow and solute transport in fractured rock masses by using the visual test with high precision and self-developed numerical simulation method. Firstly, based on the fractal theory and Monte Carlo method, the numerical model of three-dimensional rock fracture network will be established with the fracture surface roughness, aperture, length etc. following some distribution laws. Secondly, using the 3D printing technology, the transparency physical model of three-dimensional rock fracture network will be made, and the visual experimental study of fluid flow and solute transport through fractured rock masses will be carried out. Thirdly, based on the POD-Galerkin（proper orthogonal decomposition-Galerkin）method and particle tracking method, the numerical computing procedure for nonlinear flow and solute transport in three-dimensional rock fracture network will be developed. Finally, the influences of the geometric parameters of rough fracture network on the fluid flow/solute transport properties will be analyzed. The flow prediction model and comprehensive evaluation method of solute transport characteristics for three-dimensional rough-walled rock fracture network will be established, which will provide theoretical basis for the construction of underground engineering.

裂隙作为岩体内流体流动和污染物迁移的主要通道，其渗流及溶质运移特性研究是地下工程建设与环境安全的重要基础。本项目以岩体三维裂隙网络为研究对象，考虑裂隙表面粗糙性和开度各向异性，综合运用高精度可视化试验手段和自主开发数值模拟方法，揭示裂隙岩体非线性渗流及溶质运移机理。首先，基于分形理论及蒙特卡罗法，建立裂隙表面粗糙度、开度、长度等几何参数服从一定分布规律的三维裂隙网络数值模型；其次，利用3D打印技术，制作具有真实岩体三维裂隙网络结构的透明试验物理模型，开展裂隙岩体高精度可视化渗流及溶质运移试验；然后，基于本征正交分解-伽辽金法（POD-Galerkin法）及粒子追踪法，自主编制三维裂隙网络非线性渗流及溶质运移数值计算程序；最后，合理量化粗糙裂隙网络几何参数对非线性渗流及溶质运移特性的影响，建立岩体三维粗糙裂隙网络渗流预测模型及溶质运移特性综合评估方法，为地下工程建设提供理论基础。

裂隙作为岩体内流体流动和污染物迁移的主要通道，其渗流及溶质运移特性研究是地下工程建设与环境安全的重要基础。本项目构建了模拟真实岩体裂隙网络结构的三维数字模型，基于3D打印技术制作了三维粗糙裂隙网络模型试样，利用高精度裂隙岩体渗流试验装置进行了不同边界条件下的渗流试验，观测了裂隙表面粗糙度、空间分布、试样两端流体压力差对流量的影响，获得了三维粗糙裂隙网络内流体线性/非线性渗流特性及流动各向异性特性；开发了三维裂隙网络渗流及溶质运移计算程序，基于该程序，模拟了不同裂隙密度、长度、开度等几何参数对渗透率、溶质运移路径及溶质穿透曲线的影响；建立了三维岩体裂隙网络等效渗透系数预测模型，并提出了表征三维裂隙网络渗流曲折度的影响系数，同时基于裂隙网络几何分布参数和对应的平行平板模型，预测了复杂三维裂隙网络渗透系数，预测结果可作为具体工程现场裂隙岩体渗透性的预评估依据。