Home Work

HOME WORK
Foundation Engineering CEM605

Roll No........................... Max Marks 50
Note: a) All questions are compulsory and carry equal marks.
b) Assume any missing data suitably and mentioned it clearly before answering.
c) Do rough work along with your solution only.
1. a) A Concrete Pile 40 cm x 40 cm section & 20m long is driven by a drop hammer having a
weight of 40 kN& falling through a height of 1m. The average penetration under last 10 blows is
equal to 6mm per blows. The efficiency of hammer= 100%, the coefficient of restitution is 0.4
& total elastic compression 25mm. Using Hiley’s Formula Determine
(i) Qf
(ii) Qf max
b) How to prepare a ‘Bore Log Report’ for c-φ soil.

c) Calculate the ultimate bearing capacity & net ultimate bearing capacity of a rectangular
footing of size 3 m x 2 m founded at ground surface of purely cohesive soil. Water table is at
1.67 m below the ground surface. Take γsat=20 kN/m3, γw=9.81 kN/m3; unconfined compressive
strength of soil =16 kN/m3; G=2.70; e=0.70; Factor of safety=2.5. Use Terzaghi method.
d) Explain the procedure to conduct Standard Penetration Test and how to measure bearing
capacity and allowable bearing pressure by using standard penetration resistance as per IS code
provision.
e) Explain the Swedish Circle Method
2. a) A wall with a smooth vertical back and 9 metres high retains a moist cohesionless soil with
a horizontal surface. The soil weighs 15 kN/m3 and has an angle of internal friction of 30°.
Determine the total earth pressure at rest and its location. If, subsequently, the water table rises to
the ground surface, determine the increase in earth pressure at rest. Assume effective unit weight
of soil as 9 kN/m3.
b) Determine the area ratios of the samplers of the following data and comment on the values.
Sampler Do(mm) Di(mm)
Split spoon sampler 52 37
Drive tube 100 92
Shelby tube 51 49
Where, Do = Outside diameter of sampling tube
Di = Inside diameter of sampling tube
c) A retaining wall 8.5 m high retains granular fill weighing 18 kN/m3 with level surface. The
active thrust on the wall is 180 kN per metre length of the wall. The height of the wall is to be
increased and to keep the force on the wall within allowable limits, the backfill in the top-half of
the depth is removed and replaced by cinders. If cinders are used as backfill even in the
additional height, what additional height may be allowed if the thrust on the wall is to be limited
to its initial value? The unit weight of the cinders is 9.2 kN/m3. Assume the friction angle for
cinders the same as that for the soil.
d) Explain the Plate Load Test and how to measure bearing capacity and allowable bearing
pressure for different types of soil as per Plate Load Test.
e) A square group of 25 piles extends between depth of 2m & 12 m in a deposit 20m thick stiff
clay overlying rock. The piles are 0.5 m in diameter & spaced at 1m centre to centre in the
group. The undrained shear strength of the clay at the pile base level is 180 kPa & the average
value of the undrained shear strength over the depth of the pile is 110 kPa. The adhesion
coefficient (α) is 0.45. Estimate the capacity of the pile group considering overall factor of
safety equal to 3 against shear failure.
.
3. a) A retaining wall, 4.5 m high, retains a soil with c = 2 N/cm2, φ = 30° and γ = 20 kN/m3,
with horizontal surface level with the top of the wall. The backfill carries a surcharge of 20
kN/m2. Compute the total passive earth resistance on the wall and its point of application.
b) Explain the percussion and rotary boring in details.

c) List the assumptions of Terzaghi’s bearing capacity theory.
d) The pile group shown in the figure is subjected to a load of 680 kN. Calculate the
consolidation settlement. Take load dispersion from the assumed raft to be 1.5 Vertical to 1
horizontal. Width of Pile cap= 1.5m.
4. a) Write down the difference between compaction and consolidation.
b) What are different modes of failure of retaining wall? Explain with neat sketches?
c) Compute the safe bearing capacity of a continuous footing 1.75 m wide, and located at a depth
of 1.5 m below ground level in a soil with unit weight γ = 20 kN/m3, c = 25 kN/m2, and φ = 20°.
Assume a factor of safety of 2.5. Terzaghi’s bearing capacity factors for φ = 20° are Nc = 17.7,
Nq = 7.4, and Nγ = 5.0, what is the permissible load per metre run of the footing ?
d)What are the various components of a well foundation? What are their uses?
Instructions for 5th question.

1. All parts are compulsory; any unattempted part will give you negative marks proportionally.
2. Consider capillary effect only for ‘c’ part.
3. Use modified parameters (c’ & φ’) if required.
4. Take any value from all below mentioned highlighted range (red colour highlighted) upto
three decimal so that each and every student will have a different problem and solution for all the
given range. If any student found suspected that he/she has copied, will get negative marks or I
will take his/her online viva after submission.
Ex. a) If the given load is 300-350 kN, you can take 342.565 kN or any value within this range.
Ex. b) If θ = 30˚- 38˚, you can take it 35.678˚
Ex. c) If Depth of foundation/slope is given 3-5 m, you can take it 3.456 m.
Ex. d) If cohesion (c) = 80-100 kPa, you can take 85.123 kPa.
5. Any assumed value as mentioned above should be same throughout the solution.
5 a) Classify the soil which is collected from A and C layer, sieve analysis results are:
Percentage Finer
Layer WL PL
4.75 mm 1.12 mm 425 µ 150 µ 75 µ
A 84 60 30 14 10 61-64 27
C 62 54 41 34 27 48-52 32
b) A direct shear test was performed on sandy soil (A layer), sample fails at τ = 75-80 kN/m2 and
σ = 100-120 kN/m2. Calculate the shear strength parameter ‘φ’ of A layer.
c) Show the total and effective stresses diagram with capillary effect by considering capillary
zone of 1.1-1.3 m above water table having γcapillary zone = 17.1-17.6 kN/m3.
d) Give your comment on how to increase γ or φ of ‘A’ layer. (Explain any two techniques)
e) How to increase strength of layer ‘B’; write a short note on any two techniques of strength
improvement of clayey soil.
f) Calculate the consolidation settlement of 2 m clayey soil (B layer) as shown in figure with
2V:1H dispersion. (P = 300-350 kN, Cc=0.03 and e0=0.7-0.9)
g) Show the passive earth pressure diagram for given soil profile and show its point of
application.
h) Calculate the width of isolated footing for 300-350 kN load if footing is placed at a depth of
1.5-1.7 m with 2.2-2.5 FOS.
i) For the given soil profile SPT test results are given, decide a suitable depth of isolated footing
within sandy strata, calculate the ultimate bearing capacity and safe allowable pressure as per IS
code for an allowable settlement of 35-45 mm.
Depth N value
0 0
0.75 10
1.5 17
2.25 22
3 13
j) Determine the allowable pile load capacity of pile of 30-35 cm diameter and length 7-8 m.

Home Work - Cem605

Uploaded by

Copyright:

Available Formats

Home Work - Cem605

Uploaded by

Document Information

Original Title

Copyright

Available Formats

Share this document

Share or Embed Document

Sharing Options

Did you find this document useful?

Is this content inappropriate?

Copyright:

Available Formats

Home Work - Cem605

Uploaded by

Copyright:

Available Formats

Foundation Engineering CEM605

b) How to prepare a ‘Bore Log Report’ for c-φ soil.

e) Explain the Swedish Circle Method

b) Explain the percussion and rotary boring in details.

Instructions for 5th question.

You might also like