Temporary Works $($CON$4318)$

Assignment No$\mathrm{.}1$C

Steel Sheet Piling Cofferdam Design

A single$-$propped cantilever steel sheet piling cofferdam is designed to resist a $7\mathrm{.}0m$ high vertical cut. Given the following soil properties and design information:

Height of soil to be retained

Depth of the prop below ground level

Horizontal spacing of props

Active Earth Pressure Coefficient

Passive Earth Pressure Coefficient

Unit weight of soil

Surcharge Load

$7\mathrm{.}0m$

$0\mathrm{.}85m$

$3\mathrm{.}5m$

$0\mathrm{.}33$

$2\mathrm{.}75$

$18k\frac{N}{m^3}$

$20k\frac{N}{m^2}$

Use FREE EARTH SUPPORT METHOD to determine the:

a$.$ Draw the net earth pressure diagram for the Steel Sheet Piling Cofferdam with wailings and props. Determine the earth pressures at the top $(P_{ao})$ and at $7m$ below the top $(P_{ac})$ of the sheet piling cofferdam.

b$.$ Depth of point of zero net earth pressure

c$.$ Determine the strut load

d$.$ Minimum depth of embedment that the pile has to be driven if the factor of safety for moment equilibrium is designed to be not less than $2\mathrm{.}0.$

e$.$ Maximum Bending Moment and Shear Force in the Waling Member between the Prop and the Sheet Piles. Assume:

Max. Bending Moment for a continuous beam under UDL~$=\frac{1}{10}{L}^2$

Max. Shear Force ~$=0\mathrm{.}6L$