Technology of Butt Long Bolt on Roadway Supporting in Difficult Conditions

In order to solve the great deformation and roof caving problems in difficult conditions, field experiments of surrounding rocks deformation and caving co ntrol have been done in Baode mine.Experimental results indicated that a great proportion of surrounding rocks deformation are in a given deformation state, and suppo rt resistance is limitedunder the existing technical level;anchor cable stretching ability is small, which cannot adapt to difficult conditions of large quantities of roadway「 oof subsidence and a lot of anchor cables have been broken.Also, anchor cable breakage rate is positively related to the roof subsidence, and when roof subsidence is above 300 mm, anchor cable breakage rate can reach more than 50%;high-rigid anchor cable supporting method should be abandoned while high-extensive butt long b olt should be applied in roadways to adapt to the deformation of surrounding rock and continue to provide high support resistance to prevent the caving of loose surroun ding rock.Accordingly the authors put forward the support technology of replacing anchor cable with butt long bolt and increasing the coordination of supporting compon ents and roadway deformation.Industrial experiments in Baode mine shows the technology would well adapt to the surrounding rocks deformation and prevent the roof C aving caused by anchor cable breaking.