Fig. 5.
Three panels, labelled a, b and c, present stress, volumetric strain, excess pore pressure and dilatancy responses for C o T and C o P tests. Panel a contains two graphs against axial strain epsilon sub a in per cent, extending from 0 to about 22 per cent. The upper graph plots deviatoric stress q in kilopascals from 0 to 1,200. The curves represent C o T D 86 S at 50, 100 and 400 kilopascals, C o T D 91 S at 50 kilopascals, C o T D 95 S at 50 kilopascals, C o P D 86 S at 50, 100 and 400 kilopascals, C o P D 91 S at 50 kilopascals and C o P D 95 S at 50 kilopascals. The two 400 kilopascal D 86 S curves increase strongly throughout the test, reaching approximately 1,160 and 1,000 kilopascals near 18 to 20 per cent axial strain. Curves at intermediate levels rise to approximately 200 to 290 kilopascals. The remaining curves rise rapidly at low axial strain and then remain mainly around 80 to 150 kilopascals, with small fluctuations. The lower graph in panel a plots volumetric strain epsilon sub v in per cent against the same axial-strain range. Its vertical axis extends from negative 1 per cent at the top to 10 per cent at the bottom, with labelled intervals of 1 per cent. One curve moves slightly into negative volumetric strain and remains near negative 0.5 per cent. The other curves move towards increasing positive volumetric strain with axial strain. Their final values range from approximately 0.6 to 6.7 per cent, with the largest responses extending beyond 6 per cent near 18 to 20 per cent axial strain. The legend below this graph identifies the same 10 D-series datasets used in the upper graph. Panel b contains two graphs against axial strain epsilon sub a in per cent, again extending from 0 to about 22 per cent. The upper graph plots deviatoric stress q from 0 to 500 kilopascals in intervals of 50 kilopascals. One response rises steeply to approximately 450 kilopascals at low axial strain, fluctuates between approximately 330 and 430 kilopascals through the early and middle strain range, and then remains around 350 to 370 kilopascals. A second response rises rapidly to approximately 180 to 190 kilopascals and remains close to this level. Other curves initially reach approximately 80 to 130 kilopascals. Some subsequently decline progressively towards approximately zero to 20 kilopascals, while others stabilise around approximately 65 to 110 kilopascals. A lower response rises to approximately 40 kilopascals and then remains near 25 to 30 kilopascals. The lower graph in panel b plots excess pore pressure delta U in kilopascals against axial strain. Its vertical axis is arranged from negative 100 kilopascals at the top through 0 to 400 kilopascals at the bottom, with labelled intervals of 50 kilopascals. The legend identifies C o T U 86 S at 100 and 200 kilopascals, C o T U 91 S at 100 kilopascals, C o T U 95 S at 100 kilopascals, C o P U 86 S at 50, 100 and 200 kilopascals, C o P U 91 S at 100 kilopascals and C o P U 95 S at 100 kilopascals. One curve initially reaches approximately negative 70 kilopascals and then gradually approaches approximately negative 25 kilopascals. Two relatively low positive responses remain around 30 to 45 kilopascals. Several curves increase rapidly towards approximately 60 to 100 kilopascals and then change gradually. The two largest positive responses increase steeply and level near approximately 170 and 190 kilopascals. Panel c plots q over M p prime vertically from 0 to 1.2, in intervals of 0.2, against dilatancy D horizontally from negative 1.0 to 3.0, in intervals of 0.5. The legend identifies C o T D 86 S at 50, 100 and 400 kilopascals, C o T D 91 S at 50 kilopascals, C o T D 95 S at 50 kilopascals, C o P D 86 S at 50, 100 and 400 kilopascals, C o P D 91 S at 50 kilopascals and C o P D 95 S at 50 kilopascals. The datasets are represented by square, circle and triangle markers and by solid, dashed and dotted paths. Many observations cluster near q over M p prime values of approximately 0.7 to 1.0 and dilatancy values from about negative 0.5 to 0.5. Several paths extend towards positive dilatancy between approximately 0.5 and 1.2 as q over M p prime decreases towards approximately 0.2 to 0.7. A group of triangular points extends farther to approximately 2.2 dilatancy, with q over M p prime values decreasing to about 0.1 to 0.4. An open circular reference marker lies at approximately D equals 0 and q over M p prime equals 1. The accompanying annotation gives theta equals 0.00 degrees, M superscript C o T equals 1.46 and M superscript C o P equals 1.40.CoT and CoP triaxial compression tests: (a) drained tests – D: deviatoric stress–axial strain–volumetric strain; (b) undrained tests – U: deviatoric stress–axial strain–excess pore pressure; and (c) dilatancy, D–(η/ΜCoT and η/ΜCoP)