1. A proposed shopping complex include a two-storey building located close to one boundary of the site. A section of the foundation plan shown in the figure below consists of series of square footings supporting columns. The design load of the footings varies and fall in the range of 1,100 to 1,600 kN (()). Figure 2: Proposed foundation plan (not to scale) Initial geotechnical investigations on the site indicated the presence of a silty sand layer extending from the ground surface to a depth of 12 m. Properties of silty sand are assumed to be c = 0, ∅ = ,  = .  kN/m3,  = .  kN/m3 based on preliminary test results. Direct shear tests are being undertaken to confirm these values. Foundations will be placed 1.4 m below the ground surface (). For most part of the year, water table is located at 3.5 m from the ground surface. It is necessary to design a suitable size for the foundations. Q1. Using Terzaghi’s equation for ultimate bearing capacity, determine a suitable width for a square foundation that will carry a total allowable gross load, () =  kN. Use a factor of safety of 3. State any assumptions you make. Q2. It was found that the groundwater table can rise up to a level 1 m below the bottom of the foundation during the rainy season. Will the foundation width calculated in Q1 still be sufficient? If not, suggest a new width for the foundation. Q3. The following correlation exist between the net allowable bearing capacity (,) and the elastic settlement () of the foundation (Meyerhof, 1956).  is the field standard penetration number based on 60% average energy ratio.  = . Calculate the expected elastic settlement  for the foundation obtained in Q2. C B B Site boundary Proposed square foundations4 , =  .   [ ]   ≤ .   , =  .   +.   [ ]   > .    =   =  + .   , is in kN/m2 and  in mm. Q4. For the width obtained in Q2, determine the ultimate bearing capacity () and total allowable gross load (()) using the general bearing capacity equation. State any assumptions you make. How does the value you obtain here compare with the () you used in Q1? Q5. On one side of the building, site boundary is very close to the foundations. The clearance distance (c in Figure 2) from the centre of the footing to the boundary will be 0.6 m. This limits the size of the foundation to 1 m on the direction perpendicular to the boundary. Design an alternative foundation for the columns on this side. Consider a total allowable gross load of () =  kN and use Terzaghi’s bearing capacity equation. Q6. Another square foundation will be placed at the other end of the site as part of a pedestrian bridge. This section of the site is a recently filled area and has a layered ground profile as shown in Figure 3. The total allowable gross load is 1200 kN. If undrained conditions still prevails, check whether the square foundation designed in Q2 is suitable for this purpose?

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