深井软岩巷道底板下向加固钻孔孔壁稳定性研究

With the increasing of mining depth, roadway strata behaviors transformed to the whole section from ribs and roof gradually. It led to serious damage of bearing structure in roadway surrounding rock, especially the floor deformation was the biggest. Thus, the stability and quality of the hole in floor had become the bottleneck which restricted the development of floor control technology. The topic aimed at the stability problem of the downward holes wall in the process of floor reinforcing in soft rock roadway, analyzed the key factor which influenced the hole wall stability during drilling process, combined the quantitative description about appearance factor which can be measured, set up the characteristic index about the influence degree of each factor and judged the sensitivity about the influencing factors on the hole wall stability index, uncovered the instability mechanism of the downward hole wall in the condition of multi-variable coupling participation. By using cylindrical cavity expansion theory and plastoelasticity, analyzed rock mass force condition around the downward hole. Analyzed the stress field evolution law of downward hole surrounding rock in the processing of drilling with classical drilling mode, built stability model about the downward hole wall which considered the influence of key control factor. Using fractal dimension, damage variable and surface roughness of hole wall to reflect the downward hole drilling quality. Analyzed the influence law of drilling quality to rock anchor bearing strength, provided the theoretical guidance to drilling downward hole in process of reinforcing floor.

随着开采深度的增加，巷道矿压显现由帮顶逐渐转变为全断面来压，锚杆（索）和注浆加固是治理底鼓的技术方向，底板下向成孔稳定性及成孔质量是实施底板加固的前提条件。本课题针对深井软岩巷道底板下向加固钻孔孔壁稳定性问题展开研究，通过分析确定成孔过程中影响孔壁稳定性的主控因素，结合对孔壁稳定性可测显性因素的量化描述，建立各因素影响程度的特征指标，并作出各影响因素对孔壁稳定的敏感性判断，揭示下向孔孔壁多因素耦合失稳机理；利用圆柱孔扩张理论结合弹塑性力学对下向孔孔壁岩体进行弹塑性力学分析，结合典型下向孔钻进方式分析成孔过程中孔周应力场演化规律，建立考虑主控因素的深井软岩巷道下向孔孔壁稳定性模型；并通过分形维数、损伤变量、孔壁表面粗糙度等量化反映下向孔的成孔质量，进而分析其对岩锚承载强度的影响规律，为合理实施下向孔加固底板提供理论指导。

本项目以深井煤与瓦斯共采工程为背景，采用实验室试验、理论分析和数值模拟等手段研究软岩采动钻孔失稳破坏及稳定控制规律。首先以钻孔围岩小环境为研究对象，分析了钻孔挤压和剪切变形破坏机理，提出了相应的失稳判据；再以采动围岩大环境为研究对象，研究了留巷侧向顶板层间剪切滑移及采动应力分布特征，并结合前面提出的钻孔破坏判据，得出了钻孔破坏的时空演化规律，总结形成了钻孔稳定控制原理，提出了针对性的钻孔稳定控制技术，开展了系统的工程测试和应用研究，有关技术保证了抽采钻孔稳定性，钻孔抽采效率显著改善。培养博士研究生3名，发表EI/SCI论文8篇，授权发明专利8项，省部级科技进步奖2项。