Numerical Study Of Performance Of D-bolt Under Dynamic Loading

With the increasing depth of underground space development,the problem of large deformation of deep surrounding rocks represented by impact ground pressure is becoming more prominent.The frequency and grade of dynamic impact phenomena keep increasing,and the supporting system is facing serious challenges.Li et al.have conducted laboratory and field tests to study the static and dynamic performance of D-Bolt,but it requires considerable amount of manpower,materials,and time costs.In addition,the quality and quantity of experimental data adopted are often affected by external factors such as equipment and personnel fatigue.Therefore,the numerical study of its mechanical properties under dynamic loading still deserves attention.In this paper,a new type of energy-absorbing named D-Bolt is selected for modeling and analysis.The simulation of the quasi-static test includes the pullout test and the pull-shear test.The axial loading simulation using the finite element model gets consistent results with the laboratory test.Meanwhile,using the smooth particle hydrodynamic method to deal with the crushed grout body is more consistent with the test result under shear load.The influence of displacing angle and rock strength on the pull-shear test results is also explored.The modeling of dynamic performance of D-Bolt,which includes laboratory drop test,dynamic double shear test and dynamic anti-burst performance analysis were carried out on the basis of quasistatic model calibration.A parametric analysis of the dynamic drop test was conducted to prove that the load-bearing capacity of D-Bolt is directly related to the steel grade.Simulation results indicate that the higher the strength of the steel,the greater the elongation and more energy absorbed by the stretch section.In addition,results show that the longer the length of stretch bolt segment,the more energy absorption.Based on the analysis above,the dynamic double shear test and dynamic blast load analysis of D-Bolt were carried out to simulate the field conditions,in which the strength of bolt increased by1.4 times under the dynamic double shear test,and the energy absorption was about 46 k J.Under the explosion load,the axial stress in each segment of D-Bolt is uniform,and it will not be damaged under the impact of pressure with the peak value of 136 MPa.