Abstract
Abstract The numerical modelling for dynamic impact testing of end-anchored rockbolt is established in this paper. The dynamic response of rockbolt under impact loading condition is investigated considering the effects of different impact energy levels, anchoring length, bolt diameter, and material type. The results show that the stress characteristics of the anchoring section in end-anchored rockbolt could be divided into three stages with the impact time: impact initial stage, impact middle stage and impact final stage. The elongation of the rockbolt increases by about 30 mm for every 5kJ increase in impact energy. When the impact energy level increases, the energy absorption rate and maximum plastic strain both increase significantly. The impact energy is mainly dissipated by the plastic deformation of the free section and debonding section of end-anchored rockbolt. The free section plays a buffer role through its elastic deformation when the rockbolt is subjected to impact loading. It is remarkable that the energy absorption rate and anti-impact performance of the end-anchored rockbolt can be improved by increasing the bolt diameter and the bolt material strength.
Highlights
INTRODUCTIONRockbolt is one of the most effective rock support methods and has been widely used in mining and tunnelling engineering
The end-anchored rockbolt has been the primary support of roadway in the underground coal mining in China
Zhao et al (2020) developed an energy-absorbing rockbolt, called J-bolt, and the drop dynamic impact test (CANMET-MMSL facility) results show that the accumulated energy absorbing capacity reaches 46.5 kJ under impact loading condition
Summary
Rockbolt is one of the most effective rock support methods and has been widely used in mining and tunnelling engineering. The CANMET-MMSL testing machine converts the potential energy of the drop weight into kinetic energy so that impacts the anchored end of rockbolt in the steel tube and causes deformation and fail. Zhao et al (2020) developed an energy-absorbing rockbolt, called J-bolt, and the drop dynamic impact test (CANMET-MMSL facility) results show that the accumulated energy absorbing capacity reaches 46.5 kJ under impact loading condition. Mortazavi and Alavi (2013) studied the mechanical performance of fully grouted bolt under dynamic loading condition using FLAC3D and considered that the yield bolt has a better performance on absorbing dynamic stress wave He et al (2017) investigated the numerical simulation of He bolt using LS-DYNA software and verified the dynamic experimental results. The dynamic performance of end-anchored rockbolt is analyzed under different impact energy levels and the effects of anchoring length, bolt diameter and bolt material are discussed in detail
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