UBC Theses and Dissertations
Discrete element analysis of the mechanical response of bolted steel mesh supporting unstable rock on steep slopes Xu, Cong
Steel wire mesh pinned by a pattern of bolts with plates is widely used in rock slope stabilization. The bolted steel mesh can hold potentially unstable rocks in place. Typical laboratory tests on steel mesh use rigid frames to fix the mesh perimeters. However, the steel mesh is usually pinned by bolts in the field. Different configurations of bolts will affect how the mesh behaves. This research aims to develop numerical models to understand the behaviour of bolted steel mesh. Instead of using expensive and time-consuming experimental and field tests, this research takes advantage of the existing experimental results to calibrate steel mesh models using the open-source discrete element method (DEM) code YADE. Several modelling approaches were compared in terms of their mechanical response and computational cost. The particle-based mesh model was finally chosen because this approach can capture the mechanical response of steel mesh with less computational demand. The influence of different bolt patterns and bolt spacing on the force-displacement response of steel wire mesh was analyzed using a calibrated mesh model. Relationships between the resistance force provided by the mesh and the bolt density at various mesh deformations were developed. A parametric study investigated various factors that affect the mesh behaviour under loads created by an unstable rock using DEM. The results provide a better understanding of the steel mesh response for various bolt arrangements and loading conditions, which can help engineers choose the proper bolt patterns to control the mesh deformation. The simulation results were used to develop prediction models using the support vector machine (SVM) approach. The prediction models can be used to estimate the performance for bolted steel mesh. Finally, this research analyzed the interaction of the bolted mesh with a sliding and a toppling rock. The results revealed the load transfer and displacement between the rock, mesh and rockbolt plates. The research findings were demonstrated in a design of bolted mesh for a steep rock cut that was experiencing failures.
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