Abstract
After rocks are damaged under stress loading, the changes of their microstructural and mechanical properties are major factors that affect construction safety in geotechnical engineering projects. Studying the microstructures and mechanical behaviors of stress‐damaged rocks can help better guide construction and reduce construction risks for geotechnical engineering projects. In this study, a sandstone was first artificially predamaged and then subsequently subjected to scanning electron microscopy (SEM) analysis, computed tomography (CT) scanning, and uniaxial compression testing. Afterwards, the rock microstructures were three‐dimensionally (3D) reconstructed, and the pores were classified and characterized based on their diameters. Moreover, the microstructural and mechanical parameters of the rock were subjected to significance analysis. The results showed that as the stress‐induced damage (σi) increased, the uniaxial compressive strength (σc) of the soft rock decreased by 13.7–31.8%; as σi increased from 11.2 to 19.6 MPa, the elastic modulus (E) of the soft rock increased by up to 28.8%; and as σi increased beyond 19.6 MPa, there was a significant (22.3%) decrease in E. Stress‐induced damage significantly affected the spatial distribution of the pores’ structure of the soft rock. Changes in the spatial structure of the pores led to the formation of cracks. The microstructural parameters of the stress‐damaged soft rock were correlated with its mechanical parameters.
Highlights
At the microscopic level, rocks are discontinuous and inhomogeneous and contain natural defects, such as pores, cracks, and joints [1]
Samples of a soft rock which were damaged to various degrees under different stresses were subjected to scanning electron microscopy (SEM) analysis, computed tomography (CT) scanning, 3D reconstruction, and uniaxial compression testing
The sandstone pores were classified and characterized. e 3D reconstruction results visually displayed the effects of stressinduced damage on the internal microstructure of the soft rock
Summary
Rocks are discontinuous and inhomogeneous and contain natural defects, such as pores, cracks, and joints [1]. E mechanical properties of stress-damaged rocks affect construction safety in geotechnical engineering projects. To further explain the microscopic mechanisms by Advances in Civil Engineering which rocks sustain damage, some researchers have employed SEM to characterize rocks at the microscopic level. Compared to the AE technique, SEM is capable of characterizing damage-induced microstructural changes in rocks in a more accurate and comprehensive fashion. Both the SEM and AE methods are only able to qualitatively characterize rock microstructures. Some researchers have characterized and evaluated damaged rocks by the use of CT scanning [15,16,17,18]. All of these research results have demonstrated the tremendous advantages of CT scanning for characterizing rock microstructures
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