46QUESTIONS AND SOLUTIONS: CHAPTER 4 Analysis and interpretation of one-dimensional compression test data Q4.1 (a) What factors govern the relevance to a given design situation of the parameters obtained from an oedometer test? (b) Data from an oedometer test are given below. Show that the specific volume v is related to the sample height h by the expression (v/h) = constant. Plot a graph of specific volume v against the natural logarithm of the vertical effective stress, lnσ'v, and explain its shape. Calculate the values of κoand λo. σ'v, kPa 25 50 100 200 100 50 Equilibrium sample height h, mm (after consolidation has ceased) 19.86 19.56 19.27 18.48 18.79 19.08 Water content of sample at the end of the test (σ'v=50kPa, h=19.08mm): 20.88% Grain specific gravity Gs= 2.75 (c) Figure 4.40 shows the ground conditions at the site of a proposed new office building. The office building will have a raft foundation, the effect of which will be to increase the vertical effective stress in the clay layer by 50kPa throughout its depth. The oedometer test sample was taken from the mid-depth of the clay layer, i.e. 5m below ground level. Explaining your
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