Coupled FDM-DEM Modeling of Anchoring Mechanisms and Stability for Cliff Carving Conservation

The anchoring performance of anchor bolts is critical for preserving cliff carvings. To optimize reinforcement strategies, this study investigates the anchoring mechanisms and surrounding rock stability of the Chaoyang Rock carvings. A coupled FDM–DEM model, calibrated by laboratory pull-out tests, evaluated the effects of bond length and grout thickness on fully grouted rock bolts. Subsequently, a 3D topographic model assessed anchoring performance under various anchoring angles. Results indicate that increasing bond length significantly enhances peak pull-out load and post-peak friction. Conversely, increasing grout thickness improves pre-peak capacity. Pull-out damage primarily concentrates at the bolt-grout interface, propagating progressively from the loaded end. Furthermore, the anchoring angle has a significant effect on the failure mode of the slope. The anchoring angle of 15° optimally interrupts continuous high-shear-stress bands and plastic zones, effectively transferring unstable loads to deeper regions. These findings provide a rigorous theoretical foundation for optimizing anchorage parameters and developing preventive conservation strategies for cliff carvings.