Q1: On wetting, cohesive soils,

ANS:D - decrease their shear strength.

As shear strength = C + (σ)ntanθ.

On wetting c and (σ)n are modified and effective parameters are used, hence shear strength decreased. It is Only for cohesion soil.

The study was conducted for low suction range, (i.e. 0"50 kPa). The soil at the drying had lower shear strength as compared to the soil at the wetting under the same matric suction. Furthermore, the study was extended to investigate the effects of suction and the hysteresis of SWCC on shear strength parameters such as effective friction angle and the apparent cohesion, c. Results exhibited no significant effects of suction and the hysteresis of SWCC on the effective friction angle. It was observed that the apparent cohesion at the wetting was higher than that was obtained at the drying under the same suction. The c increases as the suction increase with the decreasing rate at wetting.