A soil boring log was taken from a site where the construction of a 3-story office building is planned. It is anticipated that a column load of 90 kips will rest on a 6 ft x 6 ft footing which is embedded 2 ft below the ground surface. Assume a groundwater elevation at EL. 142.40 ft.
A) Use SPT correlations from legitimate sources to estimate the unit weight of each soil layer identified in the boring log to an elevation of 108 ft (i.e. to the top of the thin limestone layer). One such source is http://www.geotechnicalinfo.com/soil_unit_weight.html, but feel free to explore other sources. Report your assigned values in a table.
B) Plot the total and effective stress distributions to the top of the thin limestone layer (EL. 108 ft).
C) Plot the change in vertical stress as a result of the square footing (to EL. 108 ft).
D) Plot the final stress (initial effective stress plus change).
The deliverables should include the following:
· a brief description of the task and any assumptions made;
· a table detailing assigned unit weights for each layer (must reference sources);
· plot of total and effective stress on the same graph;
· plot of stress increase resulting from the footing;
· plot of the final stress and initial effective stress on the same graph; and
· appendix with hand/sample calculations (either typed on plain white paper or handwritten on engineering paper).