Open-access original data for the paper of 'Laboratory Investigation on Water-induced Shear Weakening Behaviors of Sandstone Roughness-walled Joints'

Description

This is shear vs. shear displacement experimental data for roughness-walled sandstone joints under different immersed duration. those sandstone is obtained from Three Gorges Reservoir area, China. Many cubic sandstone samples with dimensions of 100×100×100 mm3 were split to obtain artificial tensile joints. Within generated joints, three pairs of joints with different roughness were selected as prototypes to be replicated, which marked as JA, JB and JC. A joint surface replication method combining 3D optical scanning and 3D rigid engraving technology was applied to produce rock joints with same surface morphology. The joint specimens were fully immersed in distilled water at room temperature (about 20℃) for different durations (30, 180, 360 days, respectively). Five joint specimens were tested at each immersion duration. The specimens were coated with waterproofing membranes after remove specimens from water to minimize water loss. As a comparison, five untreated joint specimens were used to determine dry shear behavior. Hence, a total of 60 specimens for JA, JB and JC groups were tested by direct shear tests. The PH value of used distilled water is about 6.98, which is neutral solution. Direct shear tests on joints were performed using CNL&CNS rock joint shear system at Institute of Rock and Soil Mechanics (Wuhan), China. The system is mainly composed of load and control unit, hydraulic unit, data acquisition system. During the test process, two loading modes can be used, constant normal loading and constant normal stiffness, and the maximum normal and tangential loading pressure can be applied for 200 KN and 300 KN respectively. It has an advantage of simple operation, high precision, convenient installation and uninstallation. The shear box with dimension of 100×100×100 m3 was adopted in shear tests. Five joint specimens for each immersion duration were subjected to five different normal stress, 1.0 MPa, 2.0 MPa, 3.0 MPa, 4.0 MPa and 5.0 MPa, respectively. When the joint specimen was ready to be tested, normal and shear preloading was carried out and the normal stress was held in stable condition. The normal load was then applied to the specified value at a rate of 0.1 kN/s and remained unchanged. Finally, the shear load was applied to the specimen at a loading rate of 0.5 mm/min. Once shear displacement reached to 10 mm, shear loading finished. From those data, it is shown that shear process is distinguished by three stages in entire curves for dry and immersed joints. Further analyzing shear displacement, the peak shear displacement up is no more than 3.0 mm for all tests. The average peak shear displacements immersed for 30, 180 and 360 days are smaller than that for dry sandstone joints.

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