高应力流变岩体工程开挖支护参数优化方法研究

The optimization of excavation and support parameters in underground engineering is the key point of researching on the stability of large-scale underground engineering, but there is no effective ways currently. Through the lab triaxial unloading confining pressure tests, loading and unloading creep tests of rock in this project, the relationship between long-term creep deformation of rock and irreversible deformation and its long-term strength characteristics are studied. Then the constitutive equation and damage evolution equation considering the nonlinear creep damage of rock under high stress are established. The various factors which influence the scheme of excavation and support such as the excavation size, force of support structure, the deformation, the area of plastic zone creep and damage effect of surrounding rock mass and so on, are analyzed. Then a multi-objective optimization model which considers the factors affecting the excavation and support parameters is established and using MATLAB as platform to propose a new type of efficient multi-objective optimization analysis method. Using ABAQUS as Platform and based on Python language, develop the optimization analysis platform of excavation and support parameters for underground engineering and achieve dynamic simulation for the optimization design of underground engineering. The rheological model parameters of surrounding rock will be figured out through the back analysis of field monitoring data. Based on this, the dynamic optimization analysis for the excavation and support parameters considering the long term stability of surrounding rock will be carried out. The research results provide theoretical basis for the optimization analysis of design and construction parameters in important underground engineering in our country.

地下工程开挖与支护参数优化是大型地下工程稳定性分析的重点，目前国内外还未形成一套系统有效的研究方法。本项目通过室内岩石三轴卸围压、加、卸载蠕变试验，研究岩石长期蠕变变形与不可逆变形之间的关系及其长期强度特性，建立高应力岩体非线性蠕变损伤本构模型和损伤演化方程；分析影响开挖支护方案的各项因素（如开挖尺寸，支护结构受力，围岩变形、塑性区面积及蠕变损伤效应等），建立考虑影响开挖支护参数的多目标优化模型，并基于MATLAB平台，提出一种新型、高效多目标优化分析方法；开发以ABAQUS软件为平台，Python语言为基础的地下工程开挖支护参数优化分析平台，实现地下工程优化设计的动态仿真。通过对依托工程现场监测数据的反演分析，得到围岩流变模型参数，并依此开展考虑围岩长期稳定性的依托工程开挖与支护参数的动态优化。研究成果将为我国重大地下工程设计与施工参数的优化分析提供理论基础。

地下工程开挖与支护参数优化是大型地下工程稳定性分析的重点，国内外还未形成一套系统有效的研究方法。本项目通过系统的实验室试验、理论分析、数值仿真与反馈分析相结合的研究方法，紧密围绕解决高应力流变岩体地下工程开挖与支护参数的优化问题开展深入细致的研究，主要研究成果如下：（1）建立了深部岩体非线性蠕变损伤本构模型。开展了系统的室内岩石三轴压缩和蠕变试验，研究岩石基本物理力学参数、力学行为、扩容与塑性和蠕变应变之间的关系，揭示了高应力下岩石的损伤演化与蠕变的关系，建立了考虑时间效应和应力水平影响的岩石三维损伤演化方程，并在此基础上提出了高应力工程岩体非线性蠕变损伤本构模型，然后通过编程建立了其数值仿真算法。（2）提出地下工程有限元参数化分析方法。为实现可变参数的自动建模、分析和计算，依托ABAQUS平台，基于其标准设计语言Python对其前后处理进行二次开发。在前处理方面，将模型可动边界的非线性关系编入到程序中，实现了通过用户自定义参数即可完成参数化建模、划分网格、定义集合、指定材料属性、设置分析步以及模型的自动计算；后处理方面，通过用户指定输出对象，实现对计算结果文件批量处理，输出分析数据。该研究成果极大提高了数值仿真分析问题的效率。（3）开展了基于有限元模拟的多目标优化理论模型研究。将统一目标函数法中的线性加权组合法编入MATLAB程序中与有限元参数化分析方法相互调用，实现了地下工程开挖支护参数的自动优化。项目研究成果在水电站地下厂房空间优化、浅埋偏压隧道工程设计、深部煤矿巷道支护参数优化等工程中进行了推广应用，为地下工程的设计施工提供了科学指导。