Finite element analysis of rock cutting slope reinforced by combined action of prestressed anchor cable and anchor bolt

Pointed to a seven-grade 74 meters high rock cutting slope in an expressway of Guangdong Province in China, three-dimensional elastoplastic finite element method is applied to analyze the rock cutting slope reinforced by combined action of prestressed anchor cable and anchor bolt in mountainous area. Anchorless scheme and three anchoring schemes of the cutting slope are analyzed respectively. Analysis of anchorless scheme identifies the slide face of the cutting slope and furnishes reasons to the anchoring schemes. In three anchoring schemes, prestressed anchor cable and anchor bolt are distributed by three different regulations in the cutting slope. The three-dimensional finite element analysis model of anchored slope simplifies the real anchored slope reasonably and thus the efficiency of computation is improved. In the finite element computation, the prestress of anchor cable is implemented by applying initial strain on the anchor cable elements as the loads. Computation results show that the combined action of prestressed anchor cable and anchor bolt can decrease the plastic zone of the slope effectively. Analyses show that the scheme with interlaced disposal of prestressed anchor cable and anchor bolt in each slope grade is the best scheme in three anchoring schemes for both safe and economical; and this scheme is applied to the practice of reinforcement for the above slope. Comparisons with the monitored displacements of the reinforced slope confirm the behavior predicted by the finite element analysis.