Mechanical properties and engineering application of constant resistance energy absorbing bolt

Underground engineering is faced with a large number of complex conditions such as high stress and extremely soft rock, which lead to stress concentration and energy accumulation of surrounding rock. Large deformation of surrounding rock is easy to occur. The bolt support with high strength, high prestress, high elongation and high energy absorption characteristics is an effective support method for large deformation surrounding rock. The ordinary bolt support has the problems of low strength and insufficient elongation, and the support system is easy to be broken. Based on this, the new constant resistance energy absorption bolt with high strength, high elongation and high prestress is independently developed. The static tension and dynamic impact tests of the new bolt, ordinary bolt and macro constant resistance large deformation bolt are carried out. The results show that the yield strength and breaking strength of the new bolt are 2.06 times and 1.62 times higher than those of ordinary bolt respectively, and the new bolt has the mechanical properties of high strength and constant resistance. The maximum force elongation and elongation after fracture of the new bolt are 1.52 times and 1.26 times higher than those of ordinary bolt respectively, and the energy absorbed per unit length is 3.05 times than that of the latter. The new bolt has the characteristics of high elongation and high energy absorption. In terms of dynamic performance, the average displacement of single impact of the new bolt is 47.0% lower than that of the ordinary bolt, the elongation is 1.53 times higher than that of the latter, and the energy absorbed per unit length is 2.77 times higher than that of the ordinary bolt. They indicate that the new constant resistance energy absorbing bolt has good impact resistance and overall deformation ability. The new constant resistance energy absorption bolt has the characteristics of high strength, high elongation and high energy absorption. The idea of constant resistance energy absorption bolt support is put forward. The new bolt is applied in large section roadway and deep high stress coal mine. The field monitoring results show that the support method of constant resistance energy absorption bolt can effectively control the deformation of surrounding rock. © 2022, Editorial Office of Journal of China Coal Society. All right reserved.