The safety study of bolt and cable support in shallow roadway

At present, bolt-cable combined support system is still common in shallow roadway, and the design process of bolt cable combined support system include four steps: initial design, implement design, pressure observation and modification of initial design. For modification of initial design, the rationality of support can be obtained from pressure observation that gives the prediction of deformation in roadway. However, as for whether the end of bolt and cable in surrounding rock have separated or damaged and whether the bolt and cable in surrounding rock have lost further effectiveness, it cannot help. So, evaluating the bolt-cable combined support system with new detect method has important value. This paper detects roof strata damage and working resistance of bolt (cable) in 20306 Lane Belt with Rock drilling Camera, Multi Displacement Meter and Bolt (Cable) dynamometer, analyses the development of damage (separation) in roof, and evaluates the safety of bolt or cable support system. The result shows: with the method of Rock drilling Camera, the detection of damage in surrounding rock is intuitive and true; in mining process, the number of separate zones in surrounding rock around peak pressure zones increased obviously, and cause failure of bolt and cable in this area.