A 9-in-diameter stoel pipe pile is driven into medium-dense sand to a depth of $30 \mathrm{ft}$, then load tested (for this site, the soil unit weight is
$110 \mathrm{pef}$, the angle of internal friction is $37^{\circ}$ and groundwater is below the embedicd pile). The failure losd is 70-kips (test loading when large settlement commences). Based on the small pile tip end area, assume the pile end bearing is negligible and the pile functions as a friction pile.
(a) Perform a back analysis (effective stress condition) to determine the value of the beta-coefficient ( $\beta$ ) for the pile type and soil conditions. For this analysis, assume the ratio of $8 / 0$ is 0.70 .
(b) Estimate a value for $K_f$, the final lateral pressure coefficient for the soil zone surrounding the pile shaft).
(c) Estimate a value for $K_0$ (the preconstruction lateral pressure coefficient), assuming the pile installation procedure significantly dessafies the sand so the ratio of $K_f$ to $K_0$ is 2 .