Question

Q1 (10 marks) You have been asked to examine the bearing capacity of several different rectangular pad footings. The width of each of the footings is to remain constant wil vary. In order to reduce the number of calculations, you have decided to plot the ultimate bearing capacity against the length of the footing. The properties of the underlying soil profile are given in Table 1.1. The base of the footing is to be located 1 m below ground level and ignore any effects due to a water table 2 metres, only the length Using the Brinch Hanson Method, plot the ultimate bearing capacity of the underlying soil for the footing dimensions given in Table 1.2. Note: When calculating Cav, av, round your values to the nearest multiple of 5 kPa or 5°, respectively Which dimensions yield the maximum ultimate bearing pressure? Table 1.1: Subsurface profile at the site of the proposed pad footings. y (kN/m3) Depth (m) Layer Sandy Clay Си (kPa) 0 2 20 10 18 2 4 Sand 0 35 20 Stiff Clay 4 - 10 40 5 18 Siltstone 10+ Table 1.2: Dimensions of pad footings to be plotted. Width (m) Length (m) 2 2 2 4 2 10 2 (e.g. 10000) (Continued overleaf) 1

Answer 1

Lor value of Ptat Elexible aettre 1-12 O-034 hm 34mm hence the Maximum liwut is hat s Formula te caladate xTt