致密储层砂岩裂缝动态断裂韧度测试方法及扩展机理研究

As a kind of engineering material, tight sandstone is faced with complex dynamic environment in mining, national defense engineering and tight oil or gas exploitation. At this point, this kind of engineering problem is a typical problem of rock dynamics. So far, the research on the control and mechanism of rock dynamic fracture process is still in the exploratory stage, especially for the whole process of fracture - "crack initiation, expansion and crack arrest". The dynamic fracture process can be controlled by three parameters, which is the dynamic crack initiation toughness, propagation toughness and crack arrest toughness. It has become a hot and difficult problem in the field, and the simple test method of rock dynamic arrest toughness is in a state of shortage. Based on the SCSC and ISCSC configuration, the impact experiment, numerical and theoretical research are carried out with the aid of SHPB equipment. This project focuses on the dynamic crack initiation, propagation and crack arrest toughness of quasi brittle materials, and it puts forward a new method to test the dynamic fracture toughness of the whole process. In particular, it is a convenient and stable experimental method. In this project, a new technique for numerical simulation of crack propagation is studied, and combined with the complex function, the semi analytical solution of the dynamic fracture toughness of rock under the action of the dynamic load is derived. Finally, this project will achieve the goal of quantitative study of the whole process of crack dynamic fracture, and accomplish the target of crack propagation mechanism. This research will have important scientific significance in the field of quasi brittle material fracture and disaster dynamics.

致密砂岩作为一种工程材料，在采矿、国防工程和致密油气开采等工程中面临复杂的动力环境，涉及典型岩石动力学问题，各学者至今对岩石动态断裂过程控制及机理的研究还处于探索阶段，特别针对断裂全过程-“起裂、扩展和止裂”的研究还不完善。动态裂纹断裂过程通过三个参数即可控制，为动态裂纹起裂、扩展和止裂韧度，其求解已成为该领域的热点和难点问题，岩石动态止裂韧度的简易测试方法更处于缺乏状态。本项目借助SHPB设备，基于SCSC构型及ISCSC构型进行冲击实验、数值及理论研究，重点测试致密砂岩的动态裂纹起裂、扩展及止裂韧度，提出一种便捷、稳定的单次实验测试全过程动态断裂韧度的新方法，研究用于模拟裂纹扩展的数值计算新技术，同时结合复变函数，推导出动荷载作用下新构型的岩石动态断裂韧度半解析解，实现研究裂纹动态断裂全过程定量化测试的目标，完成裂纹扩展机理研究，此研究将在准脆性材料致裂和灾害动力学领域有重要科学意义。

致密砂岩等硬岩作为一种工程材料，在采矿、国防工程和致密油气开采等工程中面临复杂的动力环境，涉及典型岩石动力学问题，至今对岩石动态断裂过程控制及机理的研究还处于探索阶段，特别针对断裂全过程（起裂、扩展和止裂）的研究还不完善。本项目的研究中，基于SHPB实验设备和“实验-数值法”，通过将冲击实验和SCSC构型、ISCSC的深度耦合，提出了一种适用于硬岩全过程断裂韧度的测试方法。并运用累计损伤和材料渐进损伤理论建立了用于岩石破坏过程分析的拉伸裂纹软化（TCS）模型，实现了准确率与计算效率的结合，形成了从细观到宏观跨尺度的岩石破坏过程模拟方法，解释了硬岩材料破坏过程中微破裂的萌生、发育、扩展、相互作用和贯通机理。同时，本项目通过推导应力波在多层地层条件下传播特征公式，实现了快速判定夹层岩石的受力状态。通过实验、理论和数值计算的结合，完成裂纹扩展机理研究，在准脆性材料致裂和灾害动力学领域有重要科学意义。研究成果在《Mechanics of Materials》、《Engineering Fracture Mechanics》、《Fatigue and Fracture of Engineering Materials and Structures》和《岩石力学与工程学报》等国内外相关领域发表论文14篇，其中SCI论文13篇，申请发明专利1项，培养博士研究生1名，硕士研究生2名。本项目为岩石工程中岩石、混凝土等准脆性材料的全过程裂纹扩展分析提供必要的理论及实验基础，其数值计算方法为大型工程建设前及建设中的风险预评估便捷应用提供技术保障，对岩石工程灾变响应具有指导意义。