Question

2) An oil tank of 20 m diameter and 10 m height is to be constructed on a saturated clay subsoil. The soil is found to have the following properties: y= 18kN/m”, c'= 15 kPa and Ⓡ' = 0°. When the tank is full, the oil makes up approximately 99% of the structure weight. The oil has a volumetric weight of y=9kN/m”. The foundation is initially designed to be constructed on the surface of the ground. Determine the factor of safety against bearing failure, assuming that for the shape factors B=L=Ø (diameter). [10 marks]

How come Nc=5.14?

Answer 1

Aco to Brinch Hansen for circular footing. Bearing capacity 24 = 1.3 CNE & INO+ 0.3 B YNY for surface footing 2=0 for clay NC= 5.14 Na = 1 My = 0 & Zu = 1:3x15x 5.14 = 100.23 krm2 2 load Capacity 100.23% 2XD? - 100. 23x x 20² = 31488. 183KN 4 weight of the tank = specific grauity & volume of all (x23x10) { = -xk gx 28274.334 km factor of Capacity load Capacity Applied load 31488-183 99 28274.334 ş Applied load 99% of structure weight } fos= 1.125