Fig. 7.
Two 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 T U 86 S, C o T U 91 S and C o T U 95 S, shearing endpoints marked by filled circles, and a dashed fitted line defined by q equals 1.02 p prime, R squared equals 0.99 and p value less than 0.0001. Multiple curved stress paths occur at increasing stress levels. Lower paths rise to approximately 30 to 60 kilopascals deviatoric stress before returning towards zero. Subsequent paths reach approximately 90, 150 to 170, and 240 to 275 kilopascals before curving downwards. Larger paths extend from around 200 to 400 kilopascals mean effective stress and return towards zero near 400 kilopascals. An upper U 95 S path rises sharply from approximately 260 kilopascals mean effective stress and 270 kilopascals deviatoric stress to a peak near 390 kilopascals deviatoric stress at about 320 kilopascals mean effective stress, then decreases slightly towards a shearing endpoint near 370 kilopascals. Shearing endpoints form an ascending sequence from low stresses through approximately 90, 165, 205 and 240 kilopascals to about 375 kilopascals deviatoric stress. The dashed fitted line rises diagonally through these endpoints from the origin to approximately 410 kilopascals deviatoric stress at 400 kilopascals mean effective stress. 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 and D 95 S as solid curves and U 86 S, U 91 S and U 95 S as dashed curves. Filled circles mark shearing endpoints. The dashed fitted line is defined by q equals 1.46 p prime, R squared equals 0.99 and p value less than 0.0001. At lower stresses, multiple D and U paths extend between approximately 0 and 300 kilopascals mean effective stress and approximately 0 and 480 kilopascals deviatoric stress. Several paths rise through shearing endpoints along the fitted line, while some U paths curve back towards zero deviatoric stress near approximately 100, 200 and 400 kilopascals mean effective stress. Other paths cluster between approximately 200 and 300 kilopascals mean effective stress and 300 to 480 kilopascals deviatoric stress. At higher stresses, closely overlapping D paths rise almost linearly from approximately 400 kilopascals mean effective stress and zero deviatoric stress to above 1,100 kilopascals deviatoric stress near 780 kilopascals means effective stress. Upper shearing endpoints occur near approximately 1,110 and 1,160 kilopascals deviatoric stress. The dashed fitted line extends diagonally from the origin through the shearing endpoints towards approximately 1,160 kilopascals deviatoric stress near 800 kilopascals mean effective stress.Stress paths at the p′–q plane for CoT tailings: (a) simple shear tests; (b) triaxial compression tests