The Numerical Simulation Of Stress Intensity Factor In Fracture Mechanics Of Frozen Soil

Based on the theory of fracture mechanics of frozen soil and finite element method (FEM), this paper presents a numerical calculation of typical experimental models, three-point bending sample of frozen soil and four-point bending sample of frozen soil, with emphasis on calculation of the stress intensity factor of spreading-open type crack (K_I) and the stress intensity factor of sliding-open type crack (K_II). And a numerical simulation is developed to solve the frost uplift problem of pile foundation.A two dimensional finite element analysis of three-point bending sample of frozen soil and four-point bending sample of frozen soil, based on FEM has been carried out to study the fracture toughness. According to the symmetry, a one-half finite element modeling of three-point bending sample is built to get the stress intensity factor of spreading-open type crack (K_I) of different sample dimension and temperature. The results are consistent with conclusion of the literatures. In this paper, a full model is established to calculate the stress intensity factor of sliding-open type crack (K_II). And the results of different sample dimension and temperature are also consistent with conclusion of the literatures.A three dimensional finite element model is established to simulate the three-point bending sample. According to the symmetry, the fracture toughness of frozen soil was calculated by a quarter models. The results of frozen soil samples with different dimension, which obtained from numerical simulation, were agreement with those of practical samples, indicating that FEM is effectual in calculating fracture toughness of frozen soil.In this paper, based on its loading condition, the frost uplift problem of pile foundation can be transferred to (I +II) tipping-open type crack model. The evaluation of this problem is realized with a full model. Drawing a comparison of the results with those derivative results, we can find that FEM numerical simulation technique is feasible and effectual. By comparing the classic method with the fracture mechanics method in evaluation of the frost uplift problem of pile foundation, a conclusion is reached that the fracture mechanics method is supplement and development of the classic method.