Soil Machenics

Question 1

Permiability of soil as a function of void ratio

Answer 1

K = c. e^3 /(1+e)

Question 2

Differential swell test and soil classification

Answer 2

10g soil sample passing 425u sieve
soaked in kerosene and distilled water
DEGREE    DFS%
Low           0 to 20 
moderate  20 to 35
high           35 to 50
very high   50 to --

Question 3

coefficient of permeability by Allen hazen

Answer 3

k =100* D(10) ^2 cm/s

D(10) effective particle size in cm

Question 4

Type of sand Fineness modulus range

Answer 4

Type of sand Fineness modulus range
Fine sand 2.2 – 2.6
Medium sand 2.6 – 2.9
Coarse sand 2.9 – 3.2

Question 5

Auger boring

Answer 5

• in partially saturated sands, silts, medium to stiff clays
• disturbed sampling
• small depth of exploration

Question 6

wash boring

Answer 6

not used in hard soils , rocks, and boulders

-disturbed samples

Question 7

percussion boring

Answer 7

only mehod to be used in bouldery and gravelly stratum

- heavy drilling bit is dropped and raised

Question 8

rotary boring

Answer 8

mud rotary boring 
core drilling (least disturbed samples)

Question 9

Sheep foot Rollers key points

Answer 9

• fine grained soil, most effective for clay
• tends to aerate the soil as it compacts,
• it is ideally suited for moisture content above acceptable range
• don’t adequately compact upper 2-3 inch, should be followed by a lighter pneumatic Tyre roller

Question 10

INDEX properties classification

Answer 10

indicative of engineering properties, can be determined more easily

SOIL GRAIN PROPERTIES
grain size
shape
density G
Grain size distribution

SOIL AGGREGATE PROPERTIES
consistency
permeability
Unconfined compressive stress
Sensitivity and  Thixotropy
relative density

Question 11

methods of obtaining flow nets

Answer 11

The following methods are available for obtaining flow nets

(a) Analytical method
(b) Electrical flow analogy
(c) Capillary flow analogy
(d) Sand model
(e) Graphical method

Question 12

Un drained shear strength relation with Ip and effective pressure

Answer 12

C / σ’ = 0.11 + 0.0037 IP (%)

Question 13

The magnitude of negative skin friction, Fng, for pile group

Answer 13

F = { C. Lc · (4B)} + {γ · Lc · B^2}

Question 14

recuperation test method

Answer 14

C/A  = ln(h1/h2)  / T
q = C/A  * Volume

Question 15

standards of proctor compaction test IS and american

Answer 15

Name       - layer-  M(Kg) - H(cm)
IS heavy -     5       4.9       45
IS light    -     3        2.6      31
Md proctor - 5       4.54    45.72
Std proctor - 3       2.5      30.5

Question 16

Classification of rocks

Answer 16

Classification of rocks: Building stones are obtained from rocks which are classified in
three ways:
1. Geological classification
2. Physical classification
3. Chemical classification
1. Geological classification: According to this classification, rocks are of the following
three types:
(i) Igneous rocks
(ii) Sedimentary rocks
(iii) Metamorphic rocks

Physical classification: This classification is based on general structure of rocks.
According to this classification, rocks are of the following three types:
(i) Stratified rocks
(ii) Unstratified rocks
(iii) Foliated rocks

Chemical classification: According to this classification, rocks are of the following
three types:
(i) Silicious rocks
(ii) Argillaceous rocks
(iii) Calcareous rocks