Question $1$

Design a retaining wall based on the geotechnical profile shown below. The geometry, dimensions and details of the wall shall be designed as part of the exercise. Design the wall according to Geoguide $1,2020.(70$ marks$)$

UDL Surcharge: $15$ kPa

$110$ mPD

AS

$=17k\frac{N}{m^3}$

Water table at $105$ mPD

$c^{\text{'}}=2$kPa

${}^{\text{'}}=28$

$104$ mPD

Soil in front of wall: Fill

$=19k\frac{N}{m^3}$

$c^{\text{'}}=6$kPa

${}^{\text{'}}=38$

$=19k\frac{N}{m^3}$

$c^{\text{'}}=3$kPa

${}^{\text{'}}=32$

Base Soil: $CDT$

$=20k\frac{N}{m^3}$

$c^{\text{'}}=4$kPa

${}^{\text{'}}=36$

In the design work, you can choose to design a mass concrete wall, invert$-$T$-$shaped or L$-$shaped retaining wall while considering the following:

Calculate and plot the lateral earth pressure

Calculate and plot the horizontal and vertical hydraulic pressure diagrams

Carry out mid$-$third check

Check stability against sliding

Check stability against overturning

Check bearing capacity $($you may apply a bearing capacity of $120$kPa if you don't want to calculate it from Geoguide $1)$

Optional: Overall Stability Check

Optional: Structural Check

The same soil profile of question $1$ is adopted but keeping the ground on the crest of the retaining wall slopping up $25$ to the horizontal. Apply the designed wall shape you made in question one, and recalculate the lateral active pressure by the wedge method of Coulomb. Please be reminded to find out the maximum lateral pressure with varies the angle of the wedge. $(30$ marks$)$

Soil in front of wall: FillY$=19$kN$/$mc$\text{'}=6$kPa'$-38\backslash$deg $10$mP$/$UDL Surcharge: $15$kPaBase Soil: CDTY$=20$kN$/$m$\text{'}$c$\text{'}=4$kPa'$=36\backslash$deg ASY$=17$kN$/$m$\}$c$\text{'}=2$kPa'$=28\backslash$deg CDTY$=19$kNmc$\text{'}=3$kPa'$320110$mPDWater table at $10$SmPD$104$mPD