Orissa University of Agriculture and Technology 2008-6th Sem B.E Civil Engineering GEOTECHNICAL ENGINEERING - exam paper

B.tech.(sem.-6th)
GEOTECHNICAL ENGINEERING (CE-304)
Max. Marks=60
SECTION-A

Q1) (10X2=20)
a) Given: e(void ratio)=0.86, w=28%,G=2.72 compute ?bulk and ?sat.
b) If at e=o.4, k(co-efficient of permeability) =0.001 cm/sec. Then, at e=o.6, k=?
c) Given: H=2m, Cv=0.00002 sq.cm/sem. (double drainage) How long it woll take to attain half of the total settlement?
d) If G=2.68, w=17%. compute theoretical maximum dry density.
e) A soil sample consists of Gravel 30%, sand 40%, silt + clay 30%.LL=33%, PI=12%. Write down soil classification as per 1498-1970.
f) Define critical hydraulic gradient.
g) Give the statement of Darcy’s legal regulations.
h) Write down particle size ranges of sand, silt and clay.
i) What is earth pressure at rest? describe it.
j) Define over-consolidation ratio.

SECTION-B
(attempt any 4 ques. ) (4X5=20)
Q2) Differentiate between:
(a) Standard and replaced Proctor tests for compaction.
(b) Compaction and Consolidation.

Q3) The subsequent data are provided for a soil sample. Porosity = 0.45, Sp.Gr of soil solids = 2.68, Moisture content = 10%. Determine the mass of water to be added to 10m³ of soil for full consolidation.
Q4) The time needed for 50% consolidation of 25mm thick clay layer (double drainage) in the laboratory is two min 20 sec. How long (in days) will it take for a 3m thick clay layer of the identical clay in the field under the identical pressure increment to reach 50% consolidation? In the field, there is a rock layer at the bottom of the clay.
Q5) Enumerate and briefly discuss the factors affecting permeability of soils.
Q6) Differentiate and compare Rankine’s and Coulomb’s theoties of earth pressure.

SECTION-C
(ATTEMPT ANY 2) (2X10=20)
Q7) Derive Terzaghi’s differential formula governing one-dimensional primary consolidation.
Q8) A retaining wall 6m high with vertical back supports a cohesive backfill having unit weight 18Kn/m³, apparent cohesion 26 Kn/m² and angle of internal friction zero. compute.
(a) Internal pressure intensity at the top of the wall.
(b) Depth of tension crack.
(c) Lateral pressure intensity at the base

Q9) Write short notes on the followings;
(a) Quick sand condition.
(b) Drainage conditions in shear strength tests.

Earning:   Approval pending.