(Solved): Figure 1a shows a 10 m thick clay layer overlying a highly permeable sand layer. = 1MPa and permeabi ...

additional surcharge loading $=100\mathrm{kN}/{\mathrm{m}}^2$ surcharge loading $=150\mathrm{kN}/{\mathrm{m}}^2$ Normally Consolidated Clay Constrained Modulus ${\mathrm{E}}_{\text{oed }}=1\mathrm{MPa}$ Permeability $k_v=k_h=1.0\times 10^{?9}\mathrm{m}/\mathrm{s}$ $10\mathrm{m}$ Saturated Sand Figure 1c (a) Using hand / manual calculations, estimate the time (from the initial loading of the original $150\mathrm{kN}/{\mathrm{m}}^2$ surcharge) that is needed for the clay layer to undergo a settlement of $\underline{2.0\mathrm{m}}$. Please show clearly your intermediate calculation steps, including any figures/charts that you use. (Strictly speaking, in the intermediate calculation steps, the clay thickness would have changed due to consolidation. However, to be consistent with the small-strain assumption, you can adopt the initial thickness of $10\mathrm{m}$ in your intermediate calculations.) (b) Set up a Plaxis model to run the same problem described above. What is the Plaxis computed settlement of the clay layer corresponding to the time obtained in question (a)? Consolidated Clay Permeability $k_v=k_h=1.0\times 10^{?9}\mathrm{m}/\mathrm{s}$ Saturated Sand Figure 1b At time $\mathbf{t}=2$ years, an additional uniformly distributed surcharge loading of 100 $\mathrm{kN}/{\mathrm{m}}^2$ is applied instantaneously on top of the original $150\mathrm{kN}/{\mathrm{m}}^2$ surcharge loading, as shown on Figure 1c. This brings the total surcharge loading to $\underline{250}$ $\mathrm{kN}/{\mathrm{m}}^2$. Figure $1\mathrm{a}$ shows a $\underline{10\mathrm{m}}$ thick clay layer overlying a highly permeable sand layer. For this assignment, the clay can be treated as a linear elastic material with ${\underline{E}}_{oed}$ $=1\mathrm{MPa}$ and permeability $k_v=k_h=1\times 10^{?9}\mathrm{m}/\mathrm{s}$. $\mathbf{n}$ At time $\mathbf{t}=0$, a uniformly distributed surcharge loading of $150\mathrm{kN}/{\mathrm{m}}^2$ is applied instantaneously over a very wide area on the surface of this clay, as shown on Figure 1b. This surcharge is left in place, and causes the underlying clay to consolidate.