Early Warning of Rock Slope Failure Based on Bolt Axial Force Monitoring

The selection of appropriate monitoring methods is necessary to realize the early warning of slope stability. In this study, a new monitoring method was proposed on the basis of bolt stress variation with reduction factors. Numerical simulation was conducted to construct a rock slope model with joint, and the monitoring bolt was placed at the joint. The relationship between bolt axial force and slope stability was investigated. Moreover, the position and inclination of the bolt were investigated thoroughly. A comprehensive comparison was conducted using an existing displacement monitoring method. Results show that (1) a single peak distribution of the bolt axial force occurs along the length, and the peak appears at the location of the joint and bolt intersection with bolt axial force saltation, which is considered the optimal axial force monitoring position. (2) Regardless of the bolt inclination, the axial force saltation constantly exists, and the internal slope stress can be monitored, except when the angle is 90°. (3) The bolt position does not influence the monitoring effects provided that the bolt penetrates the joint. (4) The axial force saltation of the bolt is earlier than the displacement saltation of the slope; this phenomenon can achieve remarkable monitoring effects appropriately for slope stability early warning.