For the conditions described, calculate the soil rigidity index I r : (a) Soil modulus of elasticity is 150 ksf, Poisson’s ratio is 0.40, soil unit weight is 115 pcf, cohesion is 600 psf, and angle of...

For the conditions described, calculate the soil rigidity index I_r
:

(a) Soil modulus of elasticity is 150 ksf, Poisson’s ratio is 0.40, soil unit weight is 115 pcf, cohesion is 600 psf, and angle of internal friction is 28°. Find Ir for a point 10 ft below the soil surface.

(b) Modulus of elasticity is 18 ksf, Poisson’s ratio is 0.45, soil cohesion is 1,200 psf (undrained shear), and soil unit weight is 105 pcf. Find I_r
for a point 8 ft below the soil surface.

(c) Modulus of elasticity is 200 ksf, Poisson’s ratio is 0.30, angle of internal friction is 35°, and soil unit weight is 122 pcf. Find I_r
for a point 10 ft below the soil surface.