Abstract：To deal with the problems associated with rock bolt materials in the coal mines，the complete support technology using prestressed steel bars，including steel bar material，locking device，component，anchoring method，machinery and procedure，was developed，based on numerical models，laboratory and field tests；according to laboratory tests，the yield strength of steel bars is not less than 1 140 MPa，the tensile strength is not less than 1 270 MPa，the extension ratio is more than 15%，the impacting absorbing energy is not less than 30 J，and the plates and locking devices compatible with the steel bar strength are developed. Numerical models are used to analyze the distribution characteristics of the stress field caused by steel bars，as well as the main affecting factors，under high prestressed conditions，the magnitude of the stress field caused by steel bars are big，the scope of compressive stress is widely spread，and the active support performance of steel bars is obvious. Field support trials using prestressed steel bars were carried out in the water-discharging roadway of Zhangcun coal mine，Luan coalfield，the displacements of roadways are moderate，no roof separation is shown，the pre-tensioned force is 100–120 kN，the force of steel bars is stable and not affected by the roadway development，and the support performance is good. The cost of using steel bars is less than that of using high strength rock bolts by 29.5%，the spacing of steel bars is big，the installation of pre-tensioned force is fast，the speed of roadway development can be improved to some extent，and this support technology is deserved to be promoted.
2015, Vol. 34 
