4. A site is underlain by a normally consolidated, saturated soil layer with thickness = 8m. The layer rests on bedrock. The lateral stress ratio of the soil is 0.5. Calculate the friction angle.

3. A site is underlain by two soil layers over bedrock. The unit weights of the top (sand) layer are 19 and 21 kN/m3 and the layer is 6 meters thick. The unit weights of the bottom (clay) layer are 20 and 22 kN/m³, and the layer is 8 meters thick. The water table is located 2 meters below the ground surface. The lateral stress ratio of the sand layer is 0.4 and that of the clay layer is 0.5. Determine the effective stress and the shear stress at point A, on a plane oriented 12 degrees clockwise from the horizontal. Use a compass to draw the Mohr Circle neatly. Note: point A is located at a depth of 10m. 5. Consider the profile in problem 3 (above) and draw the plane (in the field; denote the plane's angle of orientation) on which the magnitude of the effective stress is 60% of the magnitude of the vertical effective stress. The lateral stress ratio of the sand layer is 0.4 and that of the clay layer is 0.5. Use a compass to draw the Mohr Circle neatly.

A 15-m thick soil has water table 5 m. below the ground surface. The soil has a void ratio of 0.51 and specific gravity of 2.65. Above the water table, the soil has a degree of saturation equal to 44.4%. Direct shear test conducted on the soil shows that the an angle of internal friction of 27.45° and cohesion of 16.26 kPa. What is the potential shear strength (in kPa) on a horizontal plane at a depth of 8 m. below the ground surface? Use stored value. Answer in 5 decimal places.

20. A 17-m thick soil has water table 4 m. below the ground surface. The soil has a void ratio of 0.53 and specific gravity of 2.65. Above the water table, the soil has a degree of saturation equal to 40.67%. Direct shear test conducted on the soil shows that the an angle of internal friction of 26.04° and cohesion of 17.17 kPa. What is the potential shear strength (in kPa) on a horizontal plane at a depth of 9 m. below the ground surface? Round off to two decimal places.