a) A retaining wall is defined as a structure whose primary purpose is to provide lateral support for soil or rock. In some cases, such as basement walls and certain types of bridge abutments, it may also support vertical loads. However, if retaining walls are designed properly and constructed, there may be some failures in the structure. Discuss the following failures in the retaining walls. CR(8) b) Dewatering is a term to describe the removal of groundwater or surface water from for example a construction site. In construction the water is pumped from wells or sumps to 6 temporarily lower the groundwater levels, to allow excavation in dry and stable conditions below natural groundwater level. Discuss Open Sumps and Ditches dewatering. EV (5) c) Compute the bearing capacity per unit area of a continuous footing 3 m wide on a soil for which c = 12 KN/m2, 0=20, y=17 KN/m2 and y sub= 10 KN/m?. The depth of foundation is 3 m and the water table is at a depth of 5 m below GL. Nc=17.69, Ng = 7.44 and Ny = 3.64. Design the following footings: I. Strip footing, 3 m wide II. Square footing, 3 x 3 m III. Circular footing, 3 m diameter EV(7) d) Discuss the importance of Geotechnical designs in foundation engineering and construction.