-4 Problem 2. Based on the G/Gmax by published by Ishibashi (1992), estimate the damping ratio of this soil sample when y = 10 4at mean principal effective stress at 1, 50, 200, and 400 kPa using Ishibashi and Zhang (1993). Comment on the trend of damping ratio variation with mean principal effective stress and explain why. 1.00 0.80 11 0.60 G/Gmax 6. = 50 kN/m2 o = 200 kN/m2 = 400 kN/m3 kN/m2 0.40 0.20 Pl = 0 0.00 TTTTTTTTT 10-6 10-1 105 104 103 102 Cyclic Shear Strain Amplitude, y FIG. 9. GIG max versus y for PI = 0 with Various in G 5 1+ exp(-0.0145P1.3) = 0.333 2 [0.586 ) Gmas -1.547 + 1 G max