A circular tower grain silo is built on a concrete ring foundation (see cross-section below). The footing is founded at a depth of 0.9 m in a clay soil and is 1.1 m wide. The storage walls of the silo are 0.203 m thick and 22 m high, and are also made from concrete (take the unit weight of concrete = 22.8 kN/m). The inside diameter of the tower is 9.14 m. The grain being stored in the tower silo has a unit weight of 8 kN/m. The storage has a hemi-spherical concrete roof, which is 0.203 m thick and has the same internal and external diameters as the tower walls. The site has sedimentary rock 25 m below ground level. This is overlain by a clay stratum, which extends to the surface. The clay soil has a relatively strong, overconsolidated layer 'A' (approximately 6 m thick) overlying a normally consolidated clay layer 'B'. The water table occurs at ground level. In-situ vane and laboratory triaxial testing has indicated that the undrained shear strength Cu in each layer can be described using this equation: Cu = Cuo + .z (kPa), where Cuo is the undrained shear strength at the top of the layer (kPa), is the rate of strength increase with depth into the layer (kPa/m) and z is the depth from the top of the layer (m). For layer 'A' the values of cuo and are 100 and -13.33 respectively. For layer 'B' the values of Cuo andare 20 and 1.43 respectively. The unit weight of the clay is Y = 19 kN/m. Cross-Section Through Tower Silo TIA Clay 0.9 m 203 mm 1.1 m 9.14 m K Clay 10.4 m Concrete Silo Wall 22 m A Clay Water Concrete Ring Foundation Determine the factor of safety against bearing capacity failure (using the permissible stress method) for the tower silo, if it is completely full of grain and the filling has been rapid. Clearly state any assumptions that you make during your calculations.