Geotechnical Engineering Questions: Please use MS-Excel functions and capabilities to solve the problems.

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Q1 (20 marks)
The data depicted in the following table were obtained from a consolidated undrained (CU) triaxial test at the onse
(a) Find the soil’s effective cohesion and internal friction angle.
(b) What shear stress can be expected if the effective normal stress varying between 100 and 500 kPa?
(i.e. Create a figure showing shear stress in kPa plotted against normal stress in kPa using Terzaghi’s shear stress fo
Test stage
1
2
3
Cell pressue (kPa)
80
150
230
Deviator stress (kPa)
150
235
306
Pore pressure (kPa)
30
50
80
Q2 (20 marks)
Calculate the ultimate bearing capacity of this rectangular foundation,
using Hansen’s Eqution for various friction angles ranging from 10 to 40 degrees.
Plot the ultimate bearing capacity against the internal friction angle of soil ranging from 10 to 40 degrees.
B
q
Df
dw
Soil: clayey sand
L = 6m, B = 4m, dw = 2m, Df = 1m
c’ = 5kPa,
Saturated Unit weight = 19.8 kg/m3
Unsaturated Unit weight ≈ 19.8 kg/m3
Not to Scale
dw
m
m3
/m3
Q3 (20 marks)
A strip footing is shown in the figure. The conctrete wall is fixed into the foundation.
(a) Find the effective width,
due to the applied vertical load (250 kN pmr), horizontal load (50 kN pmr),
weight of foundation, weight of fill material and the imposed moment (M = 60 kN.m pmr).
(b) Determine the factor of safety of this foundation against bearing capacity failure
for various horizontal load ranging from 0 to 100 kN pmr.
(c) Plot factor of safety versus horizontal load ranging from 0 to 100 kN pmr.
gconcrete = 25 kN/m3
gfill (unsaturated) = 18 kN/m
gsoil (saturated) = 19.8 kN/m
fsoil = 30,
csoil = 5 kPa
M
Ground Surface
V
1.2m
0.5m
Unsaturated
Soil (Fill)
Concrete
0.4m
0.4m
H
1.5m
1.5m
Compacted Saturated Soil
Section
Not to Scale
Water Table
= 18 kN/m3
19.8 kN/m3
Water Table
Q4 (20 marks)
Determine the required width (B) of a square footing to carry a column load of 1200 kN, including the weight of fou
The depth of footing is 500 mm. A minimum factor of safety of 3 is required.
The soil below and around the footing is medium dense sand with an effective friction angle of 32 degrees and zero
The saturated unit weight of soil is 19.8 kN/m3.
The ground is flat, and the base of footing is horizontal.
The applied load is vertical with 100 mm eccentricity in both directions (B’ = L’) .
The water table is at the surface ground level.
Apply Hanssen’s Equations for calculations of bearing capacity and other required factors.
on angle of 32 degrees and zero cohesion.
Q5 (20 marks)
Find the ultimate bearing capacity of a square footing in a clayey site under undrained conditions, considering vario
The width and length of footing are both 2m and the depth of footing is also 2m. The water level is at the ground s
The applied load is vertical and uniformely distrubuted on the footing.
The ground is flat, and the base of footing is horizontal.
Plot the ultimate bearing capacity versus different cu values ranging from 40 to 150 kPa.
ed conditions, considering various undrained cohesion (cu) values ranging from 40 to 150 kPa.

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