Dynamic evolution characteristics of meso-structural mechanics performance of coal measure mudstone

Mudstone has peculiar structural properties, which have a significant impact on its strength, deformation, and other characteristics. However, there are few reports on the impact of structural properties on its yield characteristics. For the structural properties of hydrous mudstone on the yield characteristics during isotropic loading, a multifunctional triaxial apparatus was used as a research tool to conduct isotropic loading tests on four types of hydrous mudstone samples. With CT (computerized tomography) technology, the real-time dynamic scanning of mudstone samples is carried out after deformation stabilization, and the macroscopic mechanical indicators are connected with the microscopic scanning data to clarify the structural evolution law of mudstone during the loading process. The results indicate that based on the CT number (Me) reflecting the density of coal in different regions, the variation law of coal structure in resisting external loads during the loading process was explained. Before yielding, the CT number Me increases slowly, but after yielding, Me shows a linear and rapid growth trend. The change of Me values also clearly reflects the yield behavior and structural damage evolution law of mudstone loaded with different water contents. The smaller the moisture content of the mudstone sample, the greater the stress at the mudstone yields, and the structural influence of mudstone on its mechanical deformation characteristics is relatively small, but it has a strong effect on resisting external loads. The research results can provide reference for further establishing structural constitutive models of hydrous mudstone.