基于时域边界元及离散元的岩体渗流损伤耦合研究

The engineering activities by the human beings in or on the natural rock masses cause the changes of the structure of rock mass, the stress filed and the flow field in the rock mass. When the change is big enough to trigger the fracture of the intact rock in the rock mass, the interaction between the damage field and the flow field in the rock mass might happen where the stress field is also involved, which can be categorized into the scientific problem of coupling of flow and damage. The coupling of damage and flow is of significance in rock engineering. Based on fracture mechanics, damage mechanics and seepage theory in discontinuous media, numerical algorithms are proposed to be developed in the platform of the standard UDEC, by coding, incorporating and second-time developing the discrete element method program and the Time Domain Boundary Element Method (TD-BEM) for dynamics．The following three techniques are proposed to be developed: the numerical simulation technique of intact process of the damage, from the initiation of the fracture, the development of the fracture to the converging of fractures by TD-BEM for dynamics, the iterative solution technique for the nonlinear function set for the boundary integration function, and the coupling technique among TD-BEM for dynamics, damage and flow for the jointed rock mass. Upon the three developed techniques, the TD-BEM simulation for dynamics, by incorporating the coupling between damage and flow for jointed rock masses, is proposed to be carried out for both the intact rock and the jointed rock mass. The numerical results will be compared with the theoretical results in fracture mechanics, the mesoscopic experiment results from the Computerized Tomography (CT) and Scanning Electron Microscope (SEM) experiments, and hydrological and hydraulic field records in one Iron Mine for caving method, for the purpose of adjustment, improvement and verification of the numerical algorithms for coupling of seepage and damage for intact rock blocks and the jointed rock mass proposed in this research. The proposed research could simulate the complex process of the coupling of damage and flow in the jointed rock mass, by further approaching its real physical process.

人类工程活动引起岩体结构、应力场及渗流场改变，当改变超过一定限度后引起块体岩石萌生裂纹；进而引起有应力场参与的损伤场与渗流场相互共同作用，即岩体渗流损伤耦合问题，其在涉岩工程中具有普遍工程意义。课题拟以断裂力学以及损伤力学为基础，以UDEC为开发平台，通过编制、整合及二次开发离散元程序以及时域边界元程序的手段，展开岩体渗流损伤耦合的数值仿真研究。通过开发块体岩石裂纹起止全程及多裂纹交汇的时域边界元模拟技术；非线性边界积分方程组的迭代求解技术；以及时域边界元耦合的岩体渗流损伤仿真技术，实现块体岩石以及节理岩体两个层上的渗流损伤耦合的时域边界元数值仿真。通过计算结果与理论分析结果、细观实验数据（包括X射线、CT扫描以及扫描电镜试验）以及某崩落法矿山坍陷区的现场水文及水力学记录数据对比，对数值仿真计算程序进行调整、改进及验证。研究成果可使数值仿真接近真实地反映节理岩体渗流损伤耦合的复杂过程。

该项目在深入认识和研究裂纹起止以及渗流理论的基础上，以离散元程序UDEC为数值分析平台，整合时域边界元处理弹性、弹塑性问题的算法体系以及UDEC二次开发功能，建立基于时域边界元和离散元的节理岩体渗流损伤耦合仿真分析模型。同时建立了时域边界元处理弹性、弹塑性问题的算法体系，对奇异性进行了处理，开发了一套相应的计算软件。对课题展开了多种荷载作用下的算例验证，将提出的数值算法的计算结果与现有的与解析解或者特征线法解进行了比较。结果表明该项目提出的数值仿真体系和解析解有较高的吻合程度。基于时域边界元算法体系建立了定量地描述岩体裂纹萌生、发育及终止状态的模型，呈现了时域边界元法处理裂纹问题的完整过程以及核心问题，并进行了相应的算例验证。在此基础上，进行了时域边界元和离散元耦合算法研究，建立了基于裂隙网络渗流模型上的渗流场与应力场（含岩体损伤）的耦合分析体系。通过该项目，共培养了14名硕士研究生，2名博士研究生以及两名博士后，其中11名硕士已经毕业，一名博士已完成开题报告，一名博士后已出站。发表学术论文12篇，其中9篇SCI论文，获得授权发明专利3项。