Question

1. A drained direct shear box test was performed on a sample of saturated sand. The normal effective stress of 467 kPa was constant throughout the test, and the initial sample dimenstions were 60 mm x 60 mm in plan x 30 mm deep. In the vicinity of peak shear stress, the data recorded were:

(20 points)

Shear Stress, τ (kPa)	42.5	43.1	42.8
Relative horizontal displacement x (mm)	0.30	0.40	0.80
Upward movement of the shear box cap y (mm)	0.05	0.075	0.105

1. Draw the Mohr circle of stress for the soil sample when the shear stress is a maximum, stating the assumptions you made. Determine the peak friction angle (φʹ_peak).
2. Also, determine the magnitude and orientation of major and minor principal stresses with respect to the horizontal.
3. Determine the normal and shear strains near peak stress.
4. Also determine the approximate Young’s modulus of this soil.

Answer 1