More and more anchoring failure of anchorage happens in the coalmine. Base on the structure and mechanical characteristics of prestressed single anchorage, reasons of anchor failure of single anchorage included hardness difference between anchorage clip and cable strand, diameter error of cable strand, strength and hardness of cable strand, limit distance and anchorage quality are analyzed. By site investigation, quality of cable support materials and construction quality were known. Measures for solution of anchorage failure were put forward, including controlling the quality of cable and anchor strictly, defining correct limit distance, making construction standardization and strengthening testing and standard construction.
It is being used more and more widely in coal industry, because of its good flexibility, convenient construction, large anchoring depth and high prestress of small borehole cable (Kang et al. 2009). Study on cable in coal industry is changing from anchoring length and prestress to some details, such as diffusion and loss of prestress (Kang et al. 2011). But still some questions in application of small borehole cable in coal industry, just like only focusing on the length and strength, overlooking matched components such as anchorage, plate and et al. Many situations include slip of anchorage and cable being sheared caused cable failure directly, which would cause roof accident on account of large area supporting unloading suddenly. Sliding of anchorage on cable can produce spark, which brings threat to the management of gas and coal dust.
The industry has not yet attached great importance to anchoring reliability. Some engineer technicians thought that large surrounding pressure caused anchoring failure and anchorage unloading was safe, which was inconsistent with anchoring principle. The influencing factors of anchoring reliability are too much. This paper will discuss the main factors by analyzing the structure of anchorage and its compatibility with cable parameters, and put forward targeted technical measures.