Optimization of bolt rod material used in rock-burst roadway bolting

The conventional mechanical property tests and mechanical performance tests under the impact load of three bolt rod material of HRB400,HRB600 and CRM600 were conducted in the laboratory in view of large deformation and bolt fracture problem in the rock-burst roadways. The test results show that the bolt rod material of CRM600 can not only meet the requirements of conventional roadway support,but also show a superior instantaneous extension perform- ance and energy absorption ability under impact loading. The total deformation of CRM600 bolt rod material under transient impact loading is 7. 9 times of HRB600 bolt rod material,and 1. 5 times of HRB400 bolt rod material. The to- tal absorption energy of CRM600 bolt rod material in the whole impact process is 4. 2 times of HRB600 bolt rod mate- rial,and 2. 1 times of HRB400 bolt rod material. CRM600 bolts overcomes the problem of bolt rod break in the under- ground industrial test of roadway bolting support under rock-burst,and the deformation of roadway was effectively con- trolled.