4. (35 pts) Below are the Mohr's Circles that were plotted based on the results provided in Question #3. Based on this Mohr's Circle plot, answer the following questions. a)

(5 pts) What effective confining stress (o'3) was applied to each of the samples? b) (10 pts) Note that this sample was taken from about the midpoint of Layer C (as indicated by the sample depth at the top of the graph). Assuming that we are evaluating the soil strength for the design of a structure to be located in the maximum cut area of the site, do you consider the confining stress values that were selected for this test (Part a) reasonable? Why or why not? If not, what confining stresses would you have recommended instead? c) (5 pts) What effective deviator stress (ơ'1 –ơ'3) was recorded for each of the samples? d) (5 pts) Based on the deviator stresses in Part (c) and the deviator stress plots that were provided in Question 3, what failure criteria was used to create the Mohr's Circle plot? (5 percent strain, peak deviator stress, or maximum/15 percent strain) e) (10 pts) Based on this plot, what is the effective friction angle (o') for this soil? What is the effective cohesion (c')?