The Numerical Simulations And Experiment Investigation Of Nonlinear Fracture Failure Process Of Frozen Soil

As the basement of buildings in cold regions and low temperature environment of structures, frozen soil plays an important role for building safety and utility. Research on characteristics of nonlinear failure for frozen soil is the major component of frozen soil mechanics. Frozen soil is multi-phrase compound material which contains many holes and defects, and its fracture failure process has nonlinear characteristic as the same as rock and the concrete. To investigate the characteristics, in this study the fracture failure criteria are found which are applicable to frozen soil. The original state frozen soil is under a natural condition, it's constitutive relation, water and temperature distribution are near the reality. Nonlinear fracture toughness testing has been done to undisturbed frozen soil and remolded soil in Liaoning region and field testing results can be calculated by the ones of remolded soils' fracture toughness testing in lab. The results have been carefully compared, and the relations between them have been presented. Moreover, compression fracture toughness testing and compression and shear fracture toughness testing have been done in wing cracks which are never used in frozen soil testing. The main content is shown as bellow:In the first part the history of the frozen soil mechanics and fracture mechanics is introduced and the main work of this paper is drawing out.In the second part of this paper, Based on investigation of failure process of frozen soil, micro-crack damage zone is confirmed to exist, and failure of frozen soil as a result of micro-crack evaluation and connection is declared. After that, calculation models for damage zone size base on Mohr's Criterion and Maximum-Normal-Stress Criterion are put forward respectively. Think damage zone as equivalent crack, so crack size can be determined. At the end of article, equivalent crack sizes for three kinds of frozen soil are calculated, comparison of results and investigation values show that they coincided well.In the third and the fourth part, the paper presents a cementation stress crack model for automatic simulation of discrete crack propagation in frozen soil. The discrete crack is modeled based on the cementation stress crack concept using nonlinear interface elements with an exponential tensile softening constitutive law. The crack growth criterion is controlled by the maximal strain energy release rate. The propagation process of the crack is calculated with both automatic remeshing and nodal stress relaxation methods. The numerical...