基于分形重构与3D打印的深部硐室裂隙围岩非线性渗流特性

Taking the sudden inrush geological disasters of deep-buried surrounding rock with high stress and large osmotic pressure as the background, according to the fractal reconstruction and 3D printing technology, the scientific problem of nonlinear fluid flow mechanisms and critical criteria of flow regime transition for the complex fracture networks in surrounding rock of deep excavation chambers is taken as the research objective, combined with the research methods of theoretical analysis, indoor experiment, and numerical simulation. First, the spatial distribution function of three-dimensional fracture networks of the surrounding rock, which obeys the fractal law, is derived, and the data information of fracture networks with different fractal dimensions is generated. Second, 3D printing technology is used to reconstruct the fractured experimental rock mass models to conduct a series of visual fluid flow tests at high stress levels and varying water pressures. The nonlinear fitting equation describing the relation between flux and pressure gradient is established. Furthermore, by using the self-developed finite element codes, nonlinear partial differential equations of fluid flowing through the three-dimensional complex rock fracture networks with various Reynolds numbers are solved on the basis of the rank-one inverse Broyden quasi-Newton method. A critical hydraulic gradient prediction method is proposed to distinguish between the linear and nonlinear fluid flow behaviors in fracture networks, and a mathematical model for quantitatively evaluating the permeability coefficient of fracture networks correlated with the fractal dimension and stress boundary response is established using the multi-parameter regression fitting method. The dynamic evolution characteristics of the dominant flowing paths, and the nonlinear fluid flow mechanisms of the fracture networks are revealed. The research results are intended to provide certain theoretical basis for the prediction and control of sudden inrush water disasters in underground projects.

以深部高应力强渗透压硐室围岩突涌水地质灾害为背景，基于分形重构与3D打印，运用理论分析、室内试验和数值模拟相结合的方法，紧密围绕深部开挖硐室围岩裂隙网络非线性渗流机理和流态转换临界判据这一关键科学问题展开研究。首先，推导服从分形定律的围岩裂隙网络空间分布函数，生成具有不同分形维数裂隙网络数据信息；然后，利用3D打印重构三维岩体裂隙模型并开展高应力变水压条件下可视化渗流试验，建立流量与压力梯度非线性关系拟合方程；进而，自编有限元程序基于逆Broyden秩1拟牛顿迭代法求解非线性渗流偏微分方程进行不同雷诺数作用下复杂三维裂隙网络渗流数值计算，提出区分裂隙网络线性/非线性流态转换的临界水力梯度预测方法，通过多参量回归拟合建立定量评价渗透系数随分形维数及应力边界响应的数学模型，揭示裂隙网络优势渗流通道形成的动态演化特征和非线性渗流机理。研究结果拟为地下工程突涌水灾害预测及防控提供一定的理论依据。

以深部高应力强渗透压硐室围岩突涌水地质灾害为背景，基于分形重构与3D打印，运用理论分析、室内试验和数值模拟相结合的方法，紧密围绕深部开挖硐室围岩裂隙网络非线性渗流机理和流态转换临界判据这一关键科学问题展开研究。首先，推导了服从分形定律的围岩裂隙网络空间分布函数，生成了具有不同分形维数裂隙网络数据信息；然后，利用3D打印重构了三维岩体裂隙模型并开展高应力变水压条件下可视化渗流试验，建立了流量与压力梯度非线性关系拟合方程；进而，自编有限元程序基于逆Broyden秩1拟牛顿迭代法求解了非线性渗流偏微分方程进行不同雷诺数作用下复杂三维裂隙网络渗流数值计算，提出了区分裂隙网络线性/非线性流态转换的临界水力梯度预测方法，通过多参量回归拟合建立了定量评价渗透系数随分形维数及应力边界响应的数学模型，揭示了裂隙网络优势渗流通道形成的动态演化特征和非线性渗流机理。研究结果为地下工程突涌水灾害预测及防控提供一定的理论依据。项目圆满地完成了计划任务书的所有工作，发表学术论文41篇（其中第一/通讯19篇）；授权发明专利12项；获得软件著作权6项；获得江苏省科学技术二等奖（R2）等科研奖励5项；项目负责人入选2021中国科协第六届“青年人才托举工程”项目和2022江苏省优秀青年基金项目；培养研究生8名。