Study on the influence of pore water pressure on shear mechanical properties and fracture surface morphology of sandstone

• Published in: Scientific reports Vol. 14; no. 1; p. 5761
• Main Authors: Cheng, Jiaxin, Liu, Yixin, Xu, Chuanhua, Xu, Jiang, Sun, Mingzhi
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 08.03.2024; Nature Publishing Group; Nature Portfolio
• Subjects: 704/2151/2809; 704/4111; Deformation; Direct shear test; Humanities and Social Sciences; Mechanical properties; Morphology; multidisciplinary; Pore pressure; Pore water; Rock mechanics; Rocks; Sandstone; Science; Science (multidisciplinary); Shear strain; Shear strength; Shear tests; Strain; Surface morphology; Variogram; Water pressure; Direct shear test; Variogram; Pore pressure; Surface morphology
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-024-55834-8

To further investigate the weakening effect of pore water pressure on intact rock mechanics properties and characteristics of fracture surface after failure, direct shear tests of sandstone were conducted under different pore pressure. A 3D scanner was employed to digitize the morphology of the post-shear fracture surface. The variogram function was applied to quantify the anisotropic characteristics of post-shear fracture surface. The relationship between deformation during shear failure of intact rock and quantitative parameters of fracture surface after shear failure was initially established. It can be found that amplitudes of the sinusoidal surface determine the maximum value of variogram, and period affect lag distance that reach the maximum value of variogram. Test results revealed that the increase of pore pressure has obvious weakening effect on shear strength and deformation of rock. Moreover, the increase of pore pressure makes the shear fracture surface flatter. It can be obtained that both Sill max and Range max are positively related to shear strain, but negatively related to normal strain.