Abstract
In order to compare and analyze the difference in deformation and damage law of soft and hard porous media materials, the digital image correlation is used to evaluate the heterogeneous development of strain fields of hard and brittle raw coal material and soft plastic briquette coal material under uniaxial compression. Through the defined statistical indicator, the quantitative characterization of deformation localization is realized, and the material damage constitutive model based on the statistical indicator of strain field is established. The results show that the yield stage of raw coal is not obvious, showing the characteristics of strain hardening and X-shaped macroscopic shear failure. The yield stage of briquette coal is more obvious, showing the characteristics of strain softening and a tensile failure mode. The progress of strain localization can well reflect the damage and destruction process of materials. The progress of strain localization of briquette coal can be divided into uniform deformation stage, localization stage, and failure stage, while the stage characteristics of localized evolution of raw coal is not obvious. The theoretical results of the damage constitutive model defined by statistical indicator are in good agreement with the experimental data and can well reflect the stress and strain characteristics of the two materials.
Highlights
Many disasters in geotechnical engineering can be attributed to the deformation and failure of materials
The damage evolution process of materials has a certain correlation with the progress of localization of the surface deformation field, and the degree of damage and the destruction of materials can be reflected by the progress of material deformation localization [1, 2]
The deformation-damage processes of hard and brittle coal samples and soft plastic briquette coal materials are studied with the help of digital image correlation measurement method; it can be concluded that: (1) The uniaxial compression stress-strain curves of raw coal and briquette coal have typical four-stage characteristics
Summary
Many disasters in geotechnical engineering can be attributed to the deformation and failure of materials. Mostly realize early warning of engineering disasters by monitoring and analyzing the deformation process of coal, rock, and concrete These are all porous materials, and their deformation is affected by various factors such as the initial damage state, strength, and the stress environment of the material. With the help of digital image correlation, scholars all over the world have carried out a large number of studies on the deformation and damage process of coal and rock, which is mainly concentrated on the influence of changes in stress environment, initial damage, and other conditions on the evolution of coal and rock deformation fields, while there are few reports on the effect of softness and hardness on the progress of material deformation localization. Based on the defined statistical indicator, the localized development processes of the two materials were quantitatively described, and a damage constitutive model that can reflect the stress and strain characteristics of the two materials was established
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