Supporting Effect and Influence Law of Energy-Absorbing Rockbolts in Soft Rock Roadway with Large Deformation

To clarify the supporting effect and influencing factors of energy-absorbing rockbolts in soft rock roadways with large deformation, by considering four factors including rock deformation, plastic zone, rockbolt force, and stress of the surrounding rock, comparative analysis of no-rockbolt, conventional rockbolt, and energy-absorbing rockbolt schemes is conducted. The effect of the energy-absorbing rockbolt is analyzed based on a self-developed numerical simulation program, and a study is conducted on the influence of five factors such as the energy-absorption starting axial force, ultimate yielding distance on the supporting effect. The results show that: 1) Compared to conventional rockbolts, the energy-absorbing rockbolts maintain a intact support system and continuously providing support resistance within 75 d of calculation. 2) Energy-absorbing rockbolts significantly increase the maximum and minimum principal stresses of the roadway. The increase in maximum principal stress significantly enhances the range of the bearing arch in the surrounding rock. Energy-absorbing rockbolts have a high capacity to compensate for radial stresses unloaded. 3) The greater the energy-absorption starting axial force, the more significant the compensation effect of the rockbolts on the radial stress. Appropriately increasing the ultimate yielding distance and rockbolt length can effectively prevent rockbolt failure and control the area of plastic zone.