Shear Strength of Soil

Question 1

a ________ is one which acts parallel to the normal (i.e. at right angles) to the surface of an object

Answer 1

normal load or force

Question 2

a _________ is one which acts along the plane of the surface of an object

Answer 2

shear load or force

Question 3

the ________ acting on a body (either normal or shear)is the appropriate load or force divided by the area over which it acts.

Answer 3

stress

Question 4

– the net effect of all forces parallel to one direction must be zero– the net effect of all forces orthogonal (at right angles)to the above direction must be zero – the sum of the moments of the forces must be zero

Answer 4

EQUILIBRIUM

Question 5

When a body is acted upon by external forces then any plane within the body will be subjected to a stress that is generally inclined to

Answer 5

COMPLEX STRESS

Question 6

The locus of stress condition for all planes through a point

Answer 6

MOHR’S CIRCLE

Question 7

Soils generally fail in ___

Answer 7

shear

Question 8

At ______, shear stress along the failure surface(mobilized shear resistance) reaches the shear strength.

Answer 8

failure

Question 9

The soil grains slide over each other along the failure surface. No crushing of individual grains

Answer 9

Shear Failure

Question 10

is the maximum shear stress the soil can take without failure, under normal stress

Answer 10

TOTAL STRESSES

Question 11

Shear strength consists of two components:
______ and _______

Answer 11

cohesive, frictional

Question 12

c and (reduction nga symbol) are measures of _______.

Answer 12

shear strength

Question 13

The soil element does not fail if
the ________ is contained
within the envelope

Answer 13

Mohr circle

Question 14

Initially, Mohr circle is a ____

Answer 14

point

Question 15

As loading progresses, Mohr
circle becomes ______

Answer 15

larger

Question 16

failure occurs when Mohr circle touches the _______

Answer 16

envelope

Question 17

__________
initially subjected to
different isotropic stresses and then loaded
axially to failure

Answer 17

Identical specimens

Question 18

Most common laboratory tests
to determine the shear strength
parameters are

Answer 18

1.Direct shear test
2.Triaxial shear test

Question 19

Fieldt ests

Answer 19

1. Vane shear test
2. Torvane
3. Pocket penetrometer
4. Fall cone
5. Pressure meter
6. Static cone penetrometer
7. Standard penetration test

Question 20

___________ is most suitable for consolidated drained tests specially on granular soils (e.g.: sand) or stiff clays

Answer 20

Direct shear test

Question 21

to
apply vertical load

Answer 21

load framing

Question 22

to measure vertical and horizontal displacement

Answer 22

dial gauge

Question 23

to measure shear force

Answer 23

proving ring

Question 24

Sand is ______
hence c = 0

Answer 24

cohesionless

Question 25

__________ are drained and pore water pressure are dissipated hence u=0

Answer 25

Direct shear tests

Question 26

In case of clay, ___________ should be applied at a very slow rate to allow dissipation of pore water pressure(therefore, one test would take several days to finish)

Answer 26

horizontal displacement

Question 27

In many foundation design problems and retaining wall problems, it is required to determine the _________ between soil and the structural material (concrete, steel or wood)

Answer 27

angle of internal friction

Question 28

Advantages of direct shear apparatus

Answer 28

-Due to the smaller thickness of the sample, rapid drainage can be achieved -Can be used to determine interface strength parameters -Clay samples can be oriented along the plane of weakness or an identified failure plane

Question 29

Disadvantages of direct shear apparatus

Answer 29

-Failure occurs along a predetermined failure plane -Area of the sliding surface changes as the test progresses. -Non-uniform distribution of shear stress along the failure surface

Question 30

three special types of triaxial tests

Answer 30

Consolidated Drained (CD) test Consolidated Undrained (CU) test Unconsolidated Undrained(UU) test

Question 31

_______ have no cohesion.

Answer 31

Granular soils

Question 32

-no excess pore pressure throughout the test -very slow shearing to avoid build-up of pore pressure

Answer 32

Consolidated Drained (CD) Test

Question 33

-pore pressure develops during shear -faster than CD

Answer 33

Consolidated Undrained (CU) Test

Question 34

-pore pressure develops during shear -very quick test

Answer 34

Unconsolidated Undrained (UU) Test

Question 35

Unlike in the CD test, the total and the effective principal test stresses are not the same in the _____. Because the _________ at failure is measured in this test.

Answer 35

CU test, pore water pressure

Question 36

A simple way to estimate the pore pressure change in undrained loading, in terms of total stress changes ~ after Skempton(1954)

Answer 36

Skempton’s pore pressure parameters

Question 37

for saturated soils, B =1

Answer 37

B-parameter

Question 38

For normally consolidated clays Af=1 for heavily overconsolidated clays Af is negative

Answer 38

A-parameter at failure