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

Jiaxin Cheng; Yixin Liu; Chuanhua Xu; Jiang Xu; Mingzhi Sun

doi:10.1038/s41598-024-55834-8

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

Sci Rep. 2024 Mar 8;14(1):5761. doi: 10.1038/s41598-024-55834-8.

Authors

Jiaxin Cheng^{1

2}, Yixin Liu^{3

4

5

6

7}, Chuanhua Xu^{8

9

1}, Jiang Xu¹⁰, Mingzhi Sun^{8

9}

Affiliations

¹ College of Safety and Environmental Engineering, Shandong University of Science and Technology, Qingdao, 266590, China.
² State Key Laboratory of Mining Disaster Prevention and Control Co-Founded By Shandong Province and Ministry of Science and Technology, Shandong University of Science and Technology, Qingdao, 266590, China.
³ State Key Laboratory of Safety and Health for Metal Mine, Maanshan, 243071, China. yxliusafety@sdust.edu.cn.
⁴ Sinosteel Maanshan General Institute of Mining Research Co., Ltd, Maanshan, 243071, China. yxliusafety@sdust.edu.cn.
⁵ College of Resources and Environmental Engineering, Jiangxi University of Science and Technology, Ganzhou, 342399, China. yxliusafety@sdust.edu.cn.
⁶ College of Safety and Environmental Engineering, Shandong University of Science and Technology, Qingdao, 266590, China. yxliusafety@sdust.edu.cn.
⁷ State Key Laboratory of Mining Disaster Prevention and Control Co-Founded By Shandong Province and Ministry of Science and Technology, Shandong University of Science and Technology, Qingdao, 266590, China. yxliusafety@sdust.edu.cn.
⁸ State Key Laboratory of Safety and Health for Metal Mine, Maanshan, 243071, China.
⁹ Sinosteel Maanshan General Institute of Mining Research Co., Ltd, Maanshan, 243071, China.
¹⁰ State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing, 400044, China.

Abstract

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.

Keywords: Direct shear test; Pore pressure; Surface morphology; Variogram.

Grants and funding

52374214/National Natural Science Foundation of China