## 1 Introduction  
With the increase in coal mining depth in China, deep roadways face complex conditions, such as high ground stress or disturbing force, which often lead to the occurrence of rock or coal burst [1; 2; 3; 4; 5; 6]. A large number of exposed rockbolts can cause the destruction of the roadway support structure, resulting in serious casualties and economic losses [7; 8; 9; 10]. There are two important reasons for the failure of a rockbolt anchor structure under impact load. First, the surrounding rock of the deep roadway can store a significant amount of strain energy due to the effect of the high initial stress of the original rock; the rockbolt is then in a high-bearing stress environment after the deformation of the surrounding rock. Second, rockbolts are often affected by dynamic loads. These disturbances carry energy and spread in the form of stress waves and become the major inducement of rockbolt failure in deep engineering. Many experts have carried out field and laboratory experiments and theoretical analyses on rockbolts [11; 12; 13; 14; 15; 16; 17; 18; 19; 20; 21; 22; 23; 24; 25; 26]. Previous research on the dynamic response of rockbolt mostly focuses on non-damage detection technology, analyzing the vibration characteristics of the anchorage system under various excitation forces. According to the strain rate during loading, acoustic stress wave propagation in an anchorage system can be placed in the static load category. In practical engineering, blasting vibration, mine shock, rock burst and other dynamic loads are mostly in the category of medium and high strain rate. Debonding failure modes of anchor structures are distinctive with different loading modes. Rockbolt and anchoring agents are pulled out as a whole during the course of the pull-out test. Due to the opacity of the sample, the shear slip trace of the anchoring agent cannot be directly observed and judging the debonding failure only from the end failure is not convincing. It may be a single interface debonding failure mode, or a double interface debonding failure mode. These studies have contributed significantly to our understanding of the mechanical behavior of rockbolts under static or quasi-static tensile conditions, but without reference to the influence of dynamic loads. Under dynamic loads, the rockbolt in high stress surrounding rock shows different mechanical responses from static load [27; 28; 29]. Under certain conditions, even a small disturbance may induce the failure of rockbolt support in high stress engineering, resulting in the occurrence of deep rock mass disaster. The impact resistance of a rockbolt supporting structure is a research hot spot [30; 31; 32]. Many test methods have been extensively studied in the laboratory to verify the dynamic performance of rockbolts [21; 22; 31; 33]. The large amount of test data provided by dynamic impact test equipment are very valuable and have greatly promoted the development of rockbolt supports. The cumulative dynamic absorption energy of D rockbolt and J Rockbolt are measured by the canmet-MMSL testing machine, and their values reach about 46.5 kJ [15; 16; 34; 35]. In recent years, the development of numerical simulation has improved the research status of the dynamic performance of rockbolt. A numerical model of fully grouted rockbolt was made and analyzed by FLAC3D in order to investigate the influence of various parameters in the double shear test [36]. The stress characteristics of end-anchored rockbolt could be divided into three stages with the impact time [37]. The rockbolts of the dynamic test results are simulated and verified by LS-DYNA [38]. In contrast to the above, rockbolts, or end-anchored rockbolts, absorb the kinetic energy and fracture energy of rock mass by their free deformation. Although many studies on the mechanical response mechanism of rockbolt under medium and high strain rate of dynamic load have shown successful results, the mechanical properties of rockbolt under dynamic load need to be further studied.