Question $1$

The following data $($Table $1)$ was obtained from a $24-$hour maintained load

oedometer test on a sample of estuarine clay $/$ silt which was taken from a depth of $4$

m at the proposed Dargle River Crossing site in Bray, Co$.$ Wicklow, as shown on

Figure $1.$

Stress $($kPa$)$ Strain $(\%)$

$53\mathrm{.}5$

$105$

$206\mathrm{.}8$

$408\mathrm{.}5$

$8613\mathrm{.}5$

$19621$

$39227\mathrm{.}2$

$($a$)$ Determine the values of the preconsolidation pressure $($Pp$\text{'}),$ compression

index $($Cc$)$ and recompression index $($Cr$)$ from the oedometer test data;

$(50\%)$

$($b$)$ Determine the overconsolidation ratio $($OCR$)$;

$(15\%)$

$($c$)$ Using the chart shown on Figure $2$ below $($from Lambe and Whitman, $1979),$

check that the value of Cc is sensible$.$ Note e$0$ is the initial void ratio.

$(10\%)$