Fig. 8.
Two stress-path graphs, labelled a and b, plot deviatoric stress q in kilopascals vertically against mean effective stress p prime in kilopascals horizontally. In graph a, both axes range from 0 to 450 kilopascals, with major intervals of 50 kilopascals. The legend identifies C o P U 86 S, C o P U 91 S and C o P U 95 S, black circular shearing endpoints, and a dashed fitted line labelled q equals 0.999 p prime, R squared equals 0.999 and p value less than 0.000001. The three stress paths form successive curved trajectories at increasing stress levels. Lower trajectories rise to approximately 50 to 60 kilopascals deviatoric stress before returning towards the horizontal axis. Intermediate trajectories reach approximately 90 to 140 kilopascals, and subsequent trajectories reach approximately 160 to 170 kilopascals. Larger trajectories rise to approximately 160 to 200 kilopascals and then decrease towards zero near 400 kilopascals mean effective stress. Upper path segments rise through shearing endpoints to approximately 230 kilopascals deviatoric stress at about 240 kilopascals mean effective stress. The dashed fitted line rises diagonally from the origin through the shearing endpoints and continues to approximately 400 kilopascals on both axes. In graph b, the horizontal axis ranges from 0 to 800 kilopascals in major intervals of 100 kilopascals, and the vertical axis ranges from 0 to 1,200 kilopascals in major intervals of 100 kilopascals. The legend identifies D 86 S, D 91 S, D 95 S, U 86 S, U 91 S and U 95 S, black circular shearing endpoints, and a dashed fitted line labelled q equals 1.46 p prime, R squared equals 0.99 and p value less than 0.000001. At lower stresses, multiple D and U paths rise and curve between approximately 50 and 200 kilopascals mean effective stress, with some returning towards zero deviatoric stress near 100 to 200 kilopascals. Shearing endpoints form an ascending sequence from approximately 30 kilopascals deviatoric stress near 20 kilopascals mean effective stress to approximately 290 kilopascals near 200 kilopascals mean effective stress. Three higher D paths begin near 400 kilopascals mean effective stress and rise closely together, passing approximately 450 kilopascals deviatoric stress near 550 kilopascals mean effective stress, 650 kilopascals near 620 kilopascals, 800 kilopascals near 670 kilopascals, and 1,000 kilopascals near 730 kilopascals. Upper shearing endpoints occur along these paths at approximately 1,000 to 1,100 kilopascals deviatoric stress and 730 to 770 kilopascals mean effective stress. The dashed fitted line rises diagonally from the origin, follows the lower shearing endpoints and continues towards approximately 1,100 kilopascals deviatoric stress near 800 kilopascals mean effective stress.Stress paths at the p′–q plane for CoP tailings: (a) simple shear tests; (b) triaxial compression tests