Safety assessment of cable bolts subjected to tensile loads

Abstract

Cable bolts are one of the most common tension anchorage systems for reinforcing the stability of rock/soil masses; however, the quantitative assessment of cable bolt safety via numerical simulations has not been deeply explored until now. In this technical study, a bolt tri-linear tensile model and a bolt–grout (B–G) interface tri-linear shear model were integrated into a cable bolt tri-linear model to reflect the large tensile deformation-broken failure of the bolt and the B–G interface slip-softening failure after cable bolt yielding. A dimensionless index was developed by defining the maximum of the failure approach index (FAI) for bolt tensile failure and the FAI for B–G interface shear failure based of this cable bolt model to quantitatively assess the cable bolt safety. The comparison between the laboratory and numerical test results and engineering case analyses showed that the cable bolt FAI combined with the cable bolt tri-linear model, which could quantify the cable bolt safety and determine the cable bolt failure position and sequence as an improved substitute for cable bolt yield state indicators in numerical simulations. The present study is expected to offer a more accurate numerical simulation technique than existing simulation techniques in the quantitative assessment of cable bolt safety, finally contributing to the quantitative evaluation-based support design.