8/17/2019 SJBIT_Geotech - II Assignment 2
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SJB Institute of Technology
Dept. of Civil Engineering
Geotechnical Engineering – II
Assignment – II
Q. 1) For an earth retaining wall of 10m retaining a backfill of
sand carrying a surcharge of 14
kN/m2 construct the earth pressure diagram under active
condition and find the total thrust perunit length of the wall and
its location. The sand has a unit weight of 15.7 kN/m 3 and
angle of
internal friction of 300. Water table is located at a depth of
4m below ground surface and the
saturated unit weight of 19.8 kN/m3.
Q. 2) Derive the relation for lateral earth pressure and
total thrust on a retaining wall with sloping
ground.
Q. 3) List out the assumptions made and the drawbacks in
Rankine theory.
Q. 4) A wall of 8m retains sand having unit weight of
19.36kN/m3 and angle of internal friction of
340. If the surface of the backfill slopes upward at 150 to
the horizontal, find the active thrust per
unit length of the wall. Use Rankine’s conditions.
Q. 5) A retaining wall has a vertical back and is 7.32m
high. The soil is sandy loam of unit weight
17.3kN/m3. It has a cohesion of 12 kN/m2 and angle of
internal friction of 200. Neglecting wall
friction, determine the active thrust on the wall. The upper
surface of the fill is horizontal. Also,
find the resultant thrust on the wall if the drains are blocked
and water builds up behind the wall
until the water table reaches a height of 2.75m above the bottom
of the wall.
Q. 6) A retaining wall of height 6m retains two layers of
soil – top 2m is cohesionless soil with γ=
18kN/m3, φ = 30 and bottom 4m is cohesive soil with φ = 0,
C = 20kN/m 2 and γ = 16kN/m3.
Calculate the total active earth pressure on the retaining wall
and its position above the base of
retaining wall.
Q. 7) A retaining wall 8m high supports a sandy backfill
with e= 0.6, G= 2.65, φ= 30 0. Ground
water table is 2m below the ground surface. Draw the active
earth pressure diagram and
determine the magnitude and point of application of total active
earth pressure. Assume soil
above ground water table has a degree of saturation of 50%.
6th Sem B-sec
Sagar S R, MIGS, M.E
Asst. Professor
SJBIT
