Problem $2.(10$ points$)$

At $10$ m depth in sand $(=19k\frac{N}{m^3})$ the $N_{60}$ is determined as $26.$ Estimate the friction angle

using the following three empirical correlations.

a$.$ Peck et al$.(1974)$

b$.$ Schmertmann $(1975)$

c$.$ Hatanaka and Uchida $(1996)$

Given: Liao and Whitman's relationship:

$C_N=[\frac{1}{(\frac{{}_o^{\text{'}}}{p_a})}{]}^{0\mathrm{.}5}$