Morphology and failure mechanism of the shear fracture surface of weakly cemented sandstone with water saturation

The shear failure surface is formed by the fracture of weakly cemented sandstone during the damage process. The features of such surface are vastly different depending on different forces and water saturation conditions. During this study,the researcher uses 3D laser scanning to accurately measure the shear fracture surface,leverages the Geographic Information System (GIS) technology to conduct the three-dimensional visualization and quantitative anal- ysis of the surface caused by different forces and water saturation conditions,and utilizes the scanning electron micros- copy (SEM) to explore the morphology of the surface as well as its failure mechanism in a micro-level. The results show that with the increase of the angle of the fixture,the normal forces of the fracture surface decrease,which leads to the disturbances of the fracture surface and the increase of the roughness and fluctuation degree of the shear fracture surface. With the interactions of water and the sandstone,the grains of the weakly cemented sandstone skeleton swell and soften with water,and the adhesion of the skeleton particles dete-riorate,while the cementation decreases. This di- rectly leads to the decrease of the anti-shear capability of the specimen. At the same time,the impact of disturbances on the shear failure surface is reduced,thus the roughness and the fluctuation degree of the fracture surface with water saturation under the same force stress conditions are relatively small. The mechanical properties of the cemented mate- rial are the key to the morphology of the shear fracture surface of the weakly cemented sandstone,which provides an experimental foundation to further study on the damage evolution process and failure mechanism.