基于三维连续—非连续协同模型的片理状隧洞围岩精细分析方法研究

The distribution of the schistose structure in the surrounding rock is extremely dense, which is common in alignment between the basic mineral particles. Existing numerical methods are difficult to simulate the schistose structure precisely, and therefore the true numerical model of the surrounding rock cannot be established and responded the anisotropic properties. The project focuses on the difficulties in the precise numerical simulation and analysis on the surrounding schistose rock. The technical means of the in-situ investigations, laboratory experiments, numerical simulation and validation are applied. The three-dimensional (3D) discontinuous precise numerical model is constructed based on the precise simulation on the schistose structure of the surrounding rock. The precise model can respond to the anisotropic properties. Based on the search and contact determination on the complex interface, the 3D continuous-discontinuous numerical modeling method is proposed, which is applicable to the 3D complex contact interface. The concurrent connection and coupling calculation between continuous model and discontinuous model are achieved. So the numerical calculation model is provided for the superiority of the continuous numerical method and the discontinuous numerical method. Based on the tunnel and cavern engineering factors the key range of the discontinuous modeling determination method is developed. A study on the coupled analysis method for the surrounding schistose rock is carried out which is more close to the practical engineering. The more accurate, reliable, and efficient numerical simulation and analysis method are given for the overall stability of the surrounding rock.

片理状围岩中构造分布极密，常见于定向排列的基本矿物颗粒间，现有数值方法较难对片理构造进行精细模拟，因此无法建立真正意义上反演围岩各向异性特性的数值模型。本项目针对片理状围岩精细数值模拟和分析的难点，采用原位调查、室内试验、数值模拟验证的技术手段，通过对围岩片理状构造精细建模，建立反演围岩各向异性特性的三维非连续精细数值模型；基于三维复杂界面搜索和接触判定，提出适用于复杂接触界面的隧洞围岩三维连续—非连续数值建模方法，实现连续—非连续模型间协同连接和耦合计算，为充分发挥连续数值方法和非连续数值方法优势提供计算模型；提出基于隧洞工程因素的片理状围岩非连续建模关键范围的确定方法，开展更加贴近实际工程的片理状隧洞围岩耦合分析方法研究，为隧洞片理状围岩工程整体稳定性的准确分析提供更加可靠、高效的数值模拟依据和分析方法。

本项目针对片理状围岩精细数值模拟和分析的难点，提出了采用细观片理颗粒进行数值模拟岩石的方法，给出了基于颗粒流细观片理颗粒间接建模的方法，以及间接建模的完整过程和循环逻辑算法。通过对围岩片理状构造精细建模，建立反演围岩各向异性特性的三维非连续精细数值模型。开展了基于颗粒流数值模拟岩石片理构造各向异性多尺度研究，采用基于细观片理颗粒建模分析了细观颗粒形状和走向对强度的影响，发现片理颗粒走向控制着岩石的强度；采用“组合结构”模拟了片理构造的各向异性岩石，进行了细观变形和力学参数校准并确定相应的细观参数，进一步进行各向异性数值模型的数值试验，研究了细观参数长宽比的影响。建立了不同长宽比的片理构造各向异性的岩石数值模型并采用数值试验进行了测试，开展了片理构造各向异性对岩石强度参数影响研究。提出了一种能够适用于复杂协同接触界面的三维连续有限差分法—非连续颗粒离散法数值模型协同计算方法。结合有限差分法和颗粒离散元法的计算原理，提出了复杂协同界面上离散元颗粒和有限差分单元表面接触力的计算方法。建立了协同计算的流程与算法要求，针对软件特点设计了模型间数据的通信协议。实现了全域搜索、局域搜索和复杂协同界面上接触力分配三个基本模块。全域搜索模块完成了空间网格的划分，建立了能够快速检索的数据结构。局域搜索基于全域搜索建立的空间网格信息，完成了颗粒与差分单元表面的接触判断。提出了复杂协同界面条件下接触力计算与分配方法。基于三维复杂界面搜索和接触判定，提出适用于复杂接触界面的隧洞围岩三维连续—非连续数值建模方法，实现连续—非连续模型间协同连接和耦合计算，为充分发挥连续数值方法和非连续数值方法优势提供计算模型。进一步将协同算法在软件中用二次开放语言实现与验证，建立单颗粒模型验证了法向接触力和切向接触力计算的准确性，模拟竖向加载试验验证了力的传递，建立圆形隧道—围岩界面模型验证了复杂协同界面上两种模型变形的协调性，为隧洞片理状围岩工程整体稳定性的准确分析提供更加可靠、高效的数值模拟依据和分析方法。