软岩巷道锚杆孔孔底增孔锚固方式及扩孔参数研究

Study on bottom enlarged anchoring mode and reaming parameters of bolt boreholes in mine soft rock roadway

针对软岩巷道围岩变形控制问题,结合巷道围岩传统锚固系统锚固力计算方法,分析了围岩孔底增扩锚固的可行性,并给出了一种增扩锚固系统锚固力计算方法,得到了影响扩锚系统锚固力的主要因素为扩孔形状,稳定性受增扩部位围岩承载能力决定;采用理论力学和材料力学的方法建立了圆柱体增扩、倒圆台体增扩、圆台体增扩的简化力学模型,提出扩孔角θ<45°时倒圆台体增扩最优,绘制了倒圆台体增扩部位承载区域围岩应力σb与扩孔参数的二元函数关系曲线,得到了最佳扩锚长度L为130 mm、最佳扩孔角θ为15°、最佳扩孔直径D为100 mm;最后采用数值计算的方法对理论分析结果进行了验证,理论推导与模拟结果吻合。研究结果补充了软岩巷道孔底最佳扩孔参数精确理论计算方法的不足之处,为扩锚技术在软岩巷道支护中的推广应用提供理论依据。

According to the deformation control problem of the surrounding rock in the mine soft rock roadway,in combination with the an- choring force calculation method of the conventional anchoring system applied to the surrounding rock of the mine roadway, the paper had a feasibility on the bottom enlarged anchoring of the borehole in the surrounding rock and provided an anchoring force calculation method of the enlarged anchoring system. The major factors affected to the anchoring force of the enlarged anchor system were the reaming shape and the stability was affected by the bearing capacity of the surrounding rock at the enlarged reaming section. The theoretical mechanics and the material mechanics method were applied to establish the simplified mechanical model of the circular table enlarged, reversed circu- lar table enlarged and circular table enlarge. The reversed circular table enlarged optimized was provided when θ〈45°. A binary function relation curve between the surrounding rock stress σb and the reaming parameters of the enlarged reaming section bearing area for the re versed circular table was drawn. The best enlarged anchoring length obtained was 130 mm, the best enlarged angle θ was 15°and the best reaming diameter D was 100 mm. Finally,the numerical calculation method was applied to verify the theoretical analysis results and the theoretical deduction and the simulation results were fitted. The study results replenished the disadvantage of the accurate theoretical calculation method of the bottom optimized enlarged reaming parameters for the boreholes in the mine soft rock roadway and could provide the theoretical basis.