Finite element simulation of fully grouted rock bolts behaviour across varied bore hole diameters

This paper introduces a finite element (FE) method to simulate the impact of confinement conditions on the axial load-bearing capacity of fully grouted rock bolts. The study utilises a combination of experimental and numerical modelling techniques. For this purpose, two different sizes of steel sleeves were used as confinements with a diameter of 23 mm and 50 mm. The samples were cured after embedding and grouting the bolt for 28 days. Subsequently, pull-out tests were conducted to assess the axial load-bearing capacity of the samples. The results showed a direct correlation between increased confinement diameter and higher values of ultimate pull-out capacities. In addition to the experimental tests, numerical models employing ABAQUS software were developed to simulate and analyse the debonding mechanism along the bolts. By defining the appropriate model geometry, materials properties, boundary conditions, and interactions, the simulation revealed that the debonding mechanism occurred at the bolt-grout interface. Eventually, a comparison between the load-displacement curves derived from the experimental tests and the numerical simulations highlighted the effectiveness of the numerical model in accurately representing the axial load transfer mechanism within the fully encapsulated rock bolts.