由高强度低松弛预紧力钢绞线制成的矿用锚索与树脂胶结合可提供强大预应力, 加固巷道围岩和顶板破碎煤层, 但在顶板淋水条件下, 锚索自由段相比锚固段更易发生材料腐蚀致断裂失效显现。通过理论分析明晰了受腐蚀锚索自由段在拉伸作用下裂纹扩展致断裂机制, 结合实验室试验与数值模拟探寻了矿用锚索在高矿化度矿井水淋水环境下腐蚀断裂特征, 及蚀坑深度、表面腐蚀率与锚索自由段延伸率、极限载荷的相关性。研究结果表明: 锚索自由段在拉伸作用下受环境因素影响表面产生蚀坑后, 在蚀坑尖端出现应力集中, 并衍生呈裂纹扩展致脆性断裂, 其延伸率与蚀坑深度成负相关; 锚索极限载荷降低的主要影响因素为腐蚀率, 其与腐蚀率成负相关; 锚索自由段腐蚀程度为30%, 表面蚀坑深度小于0.5 mm时, 19股结构锚索承载力优于相同直径的7股锚索; 蚀坑深度大于0.5 mm时, 7股结构锚索承载力实现反超。

Mine rock cable made of high-strength and low-relaxation preload steel strand combined with resin adhesive can provide strong pre-stress to strengthen surrounding rock of roadway and fractured coal seam in roof. However, in the condition of roof flooding, the rock cable in free section is more prone to fracture failure due to material corrosion than that in anchorage section. Through theoretical analysis, the fracture mechanism caused by crack propagation under load in corroded free section of rock cable was clarified. Bu laboratory tests and numerical simulation, the corrosion fracture characteristics of rock cable under water leaching environment in high salinity mine were explored, and the correlation of cable elongation and ultimate load in free section with pit depth and surface corrosion rate was also investigated. The results show that stress concentration occurs at the tip of the pit when the cable is under load due to environmental factors, which results in brittle fracture caused by crack propagation. The elongation of the rock cable in free section is negatively correlated with the pit depth. The main factor affecting the reduction of the ultimate load of rock cables is corrosion rate, showing a negative correlation. When the surface pit depth is less than 0.5 mm, the bearing capacity of the 19-strand structural rock cable is better than that of the 7-strand structural rock cable with the same nominal diameter. When the pit depth is greater than 0.5 mm, the bearing capacity of the 7-strand structural rock cable is reverse.