Analysis on Fracture Dilation and Damage Failure of Freeze-Thaw Limestone Under Uniaxial Compression
In order to study the evolution of fracture strain and progressive damage characteristic law under uniaxial compression of freeze-thaw limestone,0,10,20 and 40 times of freeze-thaw limestone uniaxial compression experiments were carried out,the freeze-thaw limestone damage constitutive equation based on fracture body strain characteristics was established,the freeze-thaw limestone damage failure modes were explored with PFC2D numerical simulation software.The research shows that the uniaxial compressive strength,elastic modulus and Poisson's ratio of limestone decrease from 109.88 MPa,65.38 GPa,and 0.225 to 70.36 MPa,46.62 GPa,and 0.197,after 40 times of freeze-thaw cycles.The maximum values of limestone fracture body strain increase to 0.0106,0.0146,0.0269 after 10,20 and 40 times of freeze-thaw.Based on the volume strain inflection point method and the displacement regression analysis method,the freeze-thaw limestone dilation stress value decreases with the increase of the number of freeze-thaw cycles.And the relative error of the results obtained by the two methods is less than 10％.The theoretical stress-strain curve based on the fracture body strain characteristics is in good agreement with the experimental curve,the theoretical damage constitutive equation is more applicable to low freeze-thaw times of limestone.The uniaxial compression failure modes of freeze-thaw limestone based on PFC2D are split mode and"split-shear"mode.
Freeze-thaw cycleMechanical parameterFracture body strainDilation stressDamage constitutive
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