Abstract: Based on AutoCAD and OpenGL visual finite element modeling, a method is proposed for generating asphalt element in underground powerhouse finite element model through rewriting the model file with Fortran, which can significantly reduce the number of model elements and nodes and greatly boost the modeling and computational efficiency. Implicit lever element and column element are introduced to simulate asphalt-wrapped bolt and general bolt respectively and their stiffness matrixes and iterative calculation formulas are derived. This model is applied in the finite element analysis of asphalt-coating bolts for the rock-anchored beams of an underground powerhouse. The results show that adoption of this technology reduces the surrounding rock damage zone of rock wall, increases the stresses of deep bolts inside the surrounding rock and thus can improve the mechanical characteristics of rock mass in the vicinity of anchors and increase the overall safety of the surrounding rock and crane beam, which is also in line with the engineering practice. The calculation and mesh generation method in this paper are simple and easy to be implemented and it may be expected their application in the finite element analysis of similar projects.

Key words: finite elements, rock-anchored beam, asphalt, anchor bolt, grid meshing