煤壁片帮前兆信息识别与柔性加固协调变形机制研究

Wall has been recognized as a common hazard in underground coal mines, especially when mining conditions are associated with a large mining height, soft coal seam, inclined mining direction. It is often difficult to predict when and where the rib spalling failure would occur and it is also hard to assess the failure extent. In addition, several pracital problems are still existed in the widely used prevention and control measure of rib spalling, such as low support capacity, relative small elongation rate of support materials, limited time of circular progress, and high cost. In this manner, prediction and control of rib spalling has proven to be very important and difficulty in the field of host rock control.. To address rib spalling issue, a project is proposed, which named "Omen Signal Recognition and Mechanism of flexible reinforcement deformation for rib spalling". In this proposed project, effort has been toward to two part by means of protype equipment development, theoretical analysis, physical simulation, and numerical simulation. The first part is aimed to studying the factors influencing coal wall stability and the sensitivity to determine the key factors. Studying the deformation and failure characteristics of coal wall at different occurrence and mining of coal seams conditions to explore the mechanism of coal wall spalling. The second part is predict the location and time of the occurence of rib spalling, which is based on study of recognition and treatment of precursory information, such as “three dimensional non-touched test of crack at coal wall surface”, “infrared imaging based on the energy principle”, and “load characteristics of hydraulic support”. The third part is fouced on the constitutive model of supporting system for the full length anchoring support system. A support system of "coal wall + flexible material + slurry" is developed, which can be used to reveal the deformation mechanism of the reinforcement system when rib spalling has occured. The research results can provide theoretical basis for identification of precursor information and help to develop more effective control technology of rib spalling under different conditions in underground mines.

煤壁片帮发生具有“时间难预测、位置难确定、危害难预计”的特点，治理措施存在“支护强度低、材料延伸率小、循环进度短、成本高”等问题，成为大采高、仰斜开采等采场围岩控制的重点和难点。申请人已经在大采高和仰斜开采煤壁成功实验了柔性棕绳防治片帮技术，为进一步探究柔性加固机理：分析煤壁稳定性影响因素及敏感性，确定煤壁片帮主导因素；研究煤壁在不同煤层赋存和开采条件下的变形和失稳特征，探究煤壁片帮机理；基于“煤壁表面裂隙三维不接触测试”、“红外成像系统”和“液压支架载荷特征”等识别片帮前兆信息；利用分形理论描述煤壁表面裂隙与内部裂隙场的联系，预测煤壁片帮发生位置和时间；构建“煤壁+柔性材料+浆液”全长锚固支护系统的本构关系模型，探究柔性加固体系变形与失稳特征，揭示煤壁片帮柔性加固体系的协调变形机制。研究成果可以为不同条件煤壁片帮前兆信息的识别和片帮防治技术开发提供理论依据和实用。

煤壁片帮严重威胁工作面安全高效开采，是采场围岩控制的重要内容。项目针对计划任务书中4项研究内容、20个研究点、3个研究目标，采用实验设备开发、模拟实验、数值计算、理论分析等手段开展研究工作。系统研究了煤壁片帮前兆信息识别和预测方法，煤壁裂隙场、应力场和温度场的关系；提出了煤壁片帮防治柔性加固技术，建立了“煤壁-柔性材料-浆液”全长锚固支护系统的本构关系，揭示了煤壁片帮加固体系的协调变形机制，并开发了柔性加固材料，形成了煤壁破坏柔性加固成套技术。研究发现：确定了采高、支护强度、内摩擦角、护帮板高度及作用力、顶板压力对煤壁稳定性的敏感性，确定了煤壁破坏主导因素；研究了作面回采过程中煤壁表面的温度变化和应力演化特征，揭示了煤壁失稳过程中能量的耗散规律，提出了可以通过煤岩体表面裂隙场发育和温度场的变化预测煤壁的破坏方法；研制并改进了煤壁稳定性三维相似模拟实验平台，研制了动载冲击煤壁稳定性三维相似模拟实验平台，揭示了基本顶失稳产生的动载冲击作用对煤壁稳定性的影响；建立了煤壁稳定性力学模型，揭示了“硬煤劈裂式、中硬煤压剪式、软煤滑塌式”三种煤壁破坏机理；发现柔性棕绳具有延伸率大、强度高、成本低等优点，可以适应大变形煤壁的协调变形，并对煤岩体整体强度有显著提高；确立了柔性“棕绳+注浆”加固合理的布置位置约为煤壁高度的60%~70%处；研发了“超细水泥-矿粉-水玻璃混合材料”，形成的结实体便于实现煤体-结实体-柔性材料的协调变形性；开发了半环形注浆管，可以显著降低注浆钻孔的直径；形成的针对煤壁和顶板的成套加固技术，在赵固二矿、金晖瑞隆煤矿、陈蛮庄矿进行工程应用，取得了很好的社会与经济效益。研究成果为不同条件煤壁片帮前兆信息的识别和片帮防治技术开发提供理论依据，证明了煤壁柔性加固技术的有效性和科学性，丰富了煤壁破坏防治技术理论，为煤壁片帮防治提供了新思路。