1. Design a (cantilever) retaining wall that can support 8 meters of dry sand landfill with friction angle equals to 30 degree and density equals to 20kN/m3 if,

(a) the sand landfill is placed on top of the same dry sand material and,

(b) the sand landfill is placed on top of a cohesive material with zero friction angle and a 20kPa cohesion. In other words, find the minimum depth of the embedment to keep the retaining wall from collapsing. Assume that a prop is connected to the top of the retaining wall to provide horizontal support.

2. Explain the following terminologies: (a) isotropic material, (b) homogeneous material, and (c) critical state. (d) Give five examples of the stress invariants you have learned from the lectures. Explain why you consider them invariants.

3. A subrounded to subangular sand has a D10 of about 0.1mm and a uniformity coefficient of 3. The angle of shear resistance measured in the direct shear test was 47 degree. Is this reasonable? Why or why not? (Textbook Q12.30).

4. A 3 x 4 m rectangular footing is loaded uniformly by 100kPa on a landfill. Using the Newmark's method to estimate: (a) the vertical stress under the corner of the footing at the depth of 3 meter, and (b) the vertical stress under the center of the footing at the depth of 3 meters. Find m, n and the influence factors for each location and use them to find the vertical stress.

5. How far apart must two 18m diameter tanks be placed such that their stress overlapped is not greater than 10% of the contact stress at depth of 10, 20, and 30m? (Textbook 10.7).