Numerical study on the CRLD cable-rock interaction under static pull-out loading using coupled DEM-FDM method

As an effective energy-absorbing cable, constant resistance large deformation (CRLD) cables have been widely applied in rock engineering projects; however, to the best of our knowledge, its interaction mechanism with the surrounding rock has never been studied. According to previous practical projects, the CRLD cable-rock interaction differs from that of conventional cables because of the tubular expansion during the CRLD process, and it influences the performance of the cable reinforcement system. Therefore, an attempt was made to investigate the characteristics of the CRLD cable-rock interaction under static pull-out loading by using a coupled numerical method. The structure of the CRLD cable was modelled via the finite-difference method, and the surrounding rock was modelled via the discrete-element method. The micro-parameters of the surrounding rock were carefully calibrated, and the macro-parameters of the CRLD cable were verified by comparing them with a corresponding experimental test in the laboratory. The numerical results were carefully analysed. The constant resistance forces of a single CRLD cable and a CRLD cable reinforcement system were compared. The distribution of the normal and shearing stresses on the cable-rock interface was obtained, and the evolution mode of the pull-out strength was examined. In addition, the failure mode of the grouting material and surrounding rock was studied on a micro-scale. The findings describe the interaction of the CRLD cable against the surrounding rock, reveal its special anchorage mechanism, and can be used to predict and improve the performance of the CRLD cable reinforcement system.