Stability analysis method for rock blocks formed by curved fractures

Analyzing the stability of rock blocks is important in rock engineering. Most block analysis methods assume the blocks are formed by planar fractures whereas the stability of blocks formed by curved fractures are rarely investigated. However, large fractures observed in field are often curved. This paper presents a method for analyzing the stability of blocks formed by both planar and curved fractures. The blocks are represented as assemblages of element-blocks with possible cracked rock bridges. First, the triangle meshes representing the curved boundaries of blocks are simplified using an edge-collapsing-based method. Then, possible cracking rock bridges are determined by extending fracture facets and comparing the boundary surfaces in the new block system with those in the original one. The connection relation of the element-blocks are used to determine possible moving blocks, and the resisting force on rock bridges are considered when calculating the safety factor of each possible moving block. Finally, the possible moving block with the minimum safety factor is regarded as the actual moving block and the associated minimum safety factor is defined as the actual safety factor of the block. Several analytical examples are given to validate the proposed method and the results show that blocks formed by curved fractures may be unstable if the cracking of rock bridges is considered.