1 University of California, Davis Department of Civil and Environmental Engineering ECI-173 Foundation Design MEMORANDUM TO: ECI-173 Students Date: February 7, 2011 FR: Jason DeJong SUBJECT: Assignment No. 4 (Due by 4 pm Friday, February 18) Question 1: A square footing will need to support a vertical dead plus live load of 1.4 MN with a factor of safety against bearing failure of 3.0. The footing base will be placed 1.0 m below the ground surface in a deep deposit of sand. The water table is near the base of the footing. The soil's total unit weight above the water table is 17.5 kN/m 3 and below the water table is 19 kN/m 3 . Prepare a spreadsheet that computes the minimum footing width (B) required to provide adequate safety against bearing failure, and plot B versus the effective friction angle ( φ′ ) of the sand (for φ′ values of 30 ° to 45 ° ). Use the shape factors by Brinch Hansen (1970) and neglect depth factors. Question 2:
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