沿空留巷厚层软弱顶板采动裂隙分形特征及注浆扩散规律研究

Affected by strong mining, there are great differences in the crack development degree, the crack distribution and the fracture opening inside thick soft roof of gob-side entry retaining, which seriously influences the stability of the roof. Firstly, the influence factors of mining fissure of thick soft roof of gob-side entry retaining are researched to obtain the importance rank of different factors and the key factors. Secondly, the state parameter variation of the roof mining fissure network of gob-side entry retaining at different stage was studied via simulating model test, expounding the evolution regularity of the roof mining fissure. Then, based on the discrete fissure network medium theory and the fractal geometry theory, the three-dimensional fractal distribution numerical simulation model of roof mining fissure network of gob-side entry retaining was established to clarify its fractal characteristics of roof mining fissure and propose a parameter and evaluation standard for the development degree of the roof mining fissure. Finally, the numerical model and induration constitutive equation of grouting seepage spread of the roof mining fissure was established by the seepage coupling theory, which reveals the grouting diffusion law and a new technical method of the roof mining fissures of gob-side entry retaining at the edge of goaf through the grouting simulation of the roof fissures with different fractal characteristics. This study will have important theoretical value and practical guiding significance for popularization and application of gob-side entry retaining technology in deep mine.

强采动影响下沿空留巷厚层软弱顶板内部的裂隙发育程度、裂隙分布特征以及裂隙开度等存在极大的差异，严重影响顶板的稳定性。首先，探索沿空留巷厚层软弱顶板采动裂隙影响因素之间的关联性，得出各因素的重要性排序及关键因素；其次，采用相似模拟试验，研究采掘进程不同阶段沿空留巷厚层软弱顶板采动裂隙网络状态参量的变化，阐明其顶板采动裂隙时空演化规律；然后，基于离散裂隙网络介质理论和分形几何理论，建立留巷顶板采动裂隙的三维分形分布数值仿真模型，明晰顶板采动裂隙分形特征，提出一种量化顶板采动裂隙发育程度的参量和评判标准；最后，利用渗流耦合理论，建立沿空留巷厚层软弱顶板采动裂隙注浆渗流扩散数值模型和固结体本构方程，对具有不同分形特征的顶板采动裂隙进行注浆模拟，揭示留巷顶板采动裂隙注浆扩散规律与注浆新技术方法。研究成果将对沿空留巷技术在深部矿井生产中的推广应用具有重要的理论价值和现实指导意义。

沿空留巷已成为当前我国深部矿井煤炭开采的科学模式和技术发展的重要方向之一，在我国煤炭行业中得到快速发展。但在深部沿空留巷现场工程实践中发现，强采动影响下沿空留巷厚层软弱顶板内部的裂隙发育程度、裂隙分布特征以及裂隙开度等存在极大的差异，严重影响顶板的稳定性。本项目以深井沿空留巷厚层软弱顶板为研究对象，首先，将厚层软弱顶板变形破坏形式划分为8个类型，且现场实测表明厚层软弱顶板采动裂隙相对于巷道横截面垂直和水平方向呈明显不对称状态，并确定了影响厚层软弱顶板采动裂隙发育的主控因素；其次，采用相似模拟试验，阐明了采掘进程不同阶段沿空留巷厚层软弱顶板采动裂隙扩展演化规律，确定了其顶板采动裂隙不对称性分布规律及不同类型严重变形破坏程度和区位特征；然后，建立了基于深井沿空留巷厚层软弱顶板裂隙面数量的三维分形分布仿真模型，确定了顶板裂隙的线密度与分形维和顶板采动裂隙间距的分形维数；最后，建立了顶板采动裂隙注浆的平面单向流模型和顶板裂隙注浆的柱面扩散渗流模型，对具有不同分形特征的顶板采动裂隙进行注浆模拟，提出了沿空留巷厚层软弱顶板采动裂隙分区差异化注浆施工方法、顶板的帷幕注浆空间施工方法和“多支护结构”顶板控制系统，并设计了一种能有效控制厚层软弱顶板在垂直与水平方向不对称变形破坏且具有水平双向恒阻功能的新型锚索桁架。该成果应用于深井沿空留巷工程实践，顶板维护效果较好，其深浅部岩层没有出现明显离层和破碎，顶板支护结构完整。