Abstract: For large deformation roadways, because of the large amount of roof subsidence and this often leading to anchor rope breakage or support failure, in order to avoid the occurence of roof accidents and repeated reinforcing support, we developed a type of connected long bolt which is suitable for large deformation roof. Connected long bolt which is made up of left-hand thread steel metal rod body, pier coarse rod connector, connecting bolt and bolt tail thread. According to the field test, its overall mechanical properties is the same to the common steel bolt of the same diameter. In Baode Coal Mine, Shendong Coal Group, we did field tests, meanwhile the roof deep basic points displacement monitoring and connected long bolt axial force monitoring of the test roadway was carried out. The monitoring results show that connected long bolt can be synchronous with roof rock deformation, avoiding the roadway roof caving caused by anchor rope breakage because of low anchor cable elongation. Connected long bolt can control roof subsidence deformation of roadway with large deformation better. At the same time, its supporting cost was analyzed, and the result shows that replacing anchor cable with connected long bolt can greatly reduce the reinforcing supporting cost.

Key words: connected long bolt, synchronous deformation, large deformational roadway, supporting effect, supporting cost