Development of the rolling extrusion rock bolt with constant resistance and large deformation

With the increasing excavation depth of underground engineering, engineering problems such as large deformation and rock burst caused by high geo-stress brings new challenges to the excavation and reinforcement of surrounding rock in deep underground engineering. The traditional rock bolt is prone to brittle fracture under high geo-stress due to its low elongation. Therefore, this work aims to develop a novel energy-absorbing bolt with constant resistance and large displacement to reinforce the surrounding rock with a risk of large deformation or rockburst. The novel energy-absorbing bolt refereed as rolling extrusion rock bolt (RE bolt) is mainly consists of sleeve tube with a variable cross-section, energy absorption slider with steel balls embedded, steel bar connected with the energy absorption slider. The rolling extrusion is adopted to produce the resistance force of the RE bolt, which avoids the sudden attenuation of resistance force and the abrasion of the energy absorption slider. The static pull test is conducted to study the resistance force and deformation characteristics of the RE bolt with different specifications. Results imply that the RE bolt has higher resistance force, larger deformation capacity and energy absorption capacity. The work of this study provides an effective solution for the reinforcement of surrounding rock in deep rock engineering.