Anchorage mechanism of bamboo-steel composite rockbolts subjected to the coupled effect of tensile and shear stress

Earthen heritage sites have high cultural and scientific value. However, most of earthen heritage sites have been severely damaged and are in urgent need of restoration. To address this issue, a novel rockbolt, bamboo-steel composite rockbolt (BSCR), was proposed and widely employed in earthen site protection. However, the research on the anchorage mechanism of BSCR lags behind engineering practice, particularly with regard to its behavior under the coupled effect of tensile and shear stress. In this study, based on centrifugal test results, a numerical model was established and validated and a comparative analysis of the anchorage mechanism between conventional rockbolt (CR) and BSCR was also conducted. Various parameters, including rockbolt diameter, bending stiffness, inclination angle, and length, were systematically investigated to elucidate their influence on protective efficacy. BSCR has a larger diameter and bending stiffness, and is superior to CR in protecting earthen heritage sites. In addition, reducing the rockbolt inclination angle and increasing the number of rockbolt layers can reduce slope deformation caused by the coupling effect of tensile and shear stress. Increasing the length of BSCR can enhance the stability of the anchored slopes; however, due to the influence of the effective anchorage length of the rockbolt, excessively extending the rockbolt length is inefficient. These research results provide valuable insights into the application of BSCR in earthen site protection and can provide a reference for further research on its anchorage mechanism under complex stress conditions.