Papers by Author: Yi Lan Kang

Abstract: Numerical simulations of pressure loading effects on occurrence of rock lateral cracks under confining pressure were performed by using the numerical analysis software. The results indicate that the rock tends to have median cracks with the increasing of penetration under no confining pressure, while the rock tends to have lateral cracks with the increasing of penetration under confining pressure. The relative position of lateral crack initiation is dependent on the confining pressure when loading, which is independent of the penetration. The greater the confining pressure, the closer the lateral crack location to the rock surface. With the increasing of penetration and confining pressure while loading, the lateral crack direction is towards to the direction parallel to the rock surface.

Abstract: In order to determine the normal force acting on the TBM disc cutter, a 3-D FEM model is established to simulate the cutting process, with the failure effect of the rock. Afterwards, by using this model, a series of numerical simulations are performed. Based on the numerical simulation results, via modifying Evans formula, an improved formula is given. The modified formula indicates the relationship between the normal force acting on a single disc cutter and the penetration depth, and contains the influence of formation stress and wear.

Abstract: With the increasing investigation on reliability and stability of engineering structures, it becomes important for reseach on mechanical properties of materials under fracutre conditions. Concerning to fracture problems of large deformation materials, deformation characteristics of the crack tip field is necessarily needed. This paper presents an experimental analysis on a double-cracked rubber disk under the I-II mixed-mode fracture condition. Deformation properties around the crack tip are described through analyzing displacement information acquired by digital moiré method of circular and radial gratings. Also the existence of sector division mode under mixed loading condition is verified, and it is also found experimentally that the shear component makes the sectors shift.