A farmer requires two steel silos to store wheat. Each silo is 8 m in external diameter and 10 m high. The foundation for each silo is a circular concrete slab thickened at the edge. The total load of each silo filled with wheat is 9552 kN. The soil consists of a 30 m thick deposit of medium clay above a deep deposit of very stiff clay. The farmer desires that the silos be a distance of 2 m apart and hires you to recommend whether this distance is satisfactory. The area is subjected to a gust wind speed of 100 kilometers per hour.
(a) Plot the distribution of vertical stress increase at the edges and at the center of one of the silos up to a depth of 16 m. Assume the soft clay layer is semi-infinite and the concrete slab is flexible. Use a spreadsheet to tabulate and plot your results.
(b) Calculate the elastic settlement at the surface of one of the silos at the edges and at the center, assuming E = 30 MPa and v = 0.7.
(c) Calculate the elastic tilt of the foundation of one of the silos and sketch the deformed shape of the foundation slab.
(d) Would the tops of the silos touch each other based on the elastic tilt? Show calculations in support of your answer.
(e) What minimum separation distance would you recommend? Make clear sketches to explain your recommendation to the owner.
(f) Explain how the wind would alter the stress distribution below the silos. (Hint: Use the charts in Appendix B.)