关键词: 地下洞室围岩, 喷混凝土, 钢纤维, 三维离散单元法, 抗弯试验, 细观破裂过程, 丰宁抽水蓄能电站

Abstract: The bending resistance of shotcrete is an important reflection of its support strength. Steel fiber reinforced concrete is adopted as the shotcrete for the underground powerhouse of Fengning pumped storage power station. In this study, numerical bending test of the shotcrete is carried out by using 3D discrete element code. During the numerical bending test, a triangulation modeling method based on the Voronoi tessellation is proposed. The Monte-Carlo method was used to establish the random distributed steel fibers, Coulomb-sliding joint constitutive model to represent the linking-breaking effects between concrete mediums, while Cable model to simulate the reinforcement effects of steel fibers. Numerical results are basically consistent with laboratory test curves. The bending failure of the steel fiber reinforced shotcrete is dominated by tensile fractures. The tensile fracture path is generally vertically upward, but is affected by the action of steel fibers. In the process of the bending failure of steel fiber reinforced shotcrete, the yield of steel fibers is mostly due to the yield of the bonding force between steel fibers and concrete, which echoes laboratory tests when many steel fibers are pulled out.

Key words: surrounding rock, shotcrete, steel fiber, 3D discrete element method, bending test, micro failure process, Fengning pumped storage power station