Q1. Assuming that the clay soil has a yielding function as the following: 9 (p)-p'p+ = 0 M where p' is the mean effective stress, and q is the deviatoric stress. p' is the effective preconsolidation stress. M is the material property. A clay soil was consolidated to a mean effective stress of 100 kPa (p = 600 kPa). If M= 1, plot the yielding curve in the p'-q space.