This document discusses various methods for analyzing the stability of finite slopes, including the Swedish circle method, friction circle method, Taylor stability number method, Bishop's method, and Culmann's method. The Swedish circle method models the failure surface as an arc of a circle and considers cases of purely cohesive soil and cohesive-frictional soil. The friction circle method also assumes a circular failure surface and models resisting forces. Taylor's stability number relates the stabilizing cohesive force to the slope height and cohesion. Bishop's method accounts for inter-slice forces and pore water pressure. Culmann's method assumes a planar failure surface passing through the toe.

1. BAMBHANIYA AKSHAYKUMAR :-
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DUMANIYA KIRPAL :-
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MAKWANA KETAN :- 160180106052
GUIDED BY :- M.A.S.
GOVERNMENT ENGINEERING COLLEGE
DAHOD

2. SOIL MECHANICS
Stability of slopes
 TOPIC :- Stability of finite slopes
Swedish circle method,
friction circle method,
Taylor stability number,
Bishop`s method,
Culmann`s method

3. Stability Analysis of Finite
Slopes
 if slope is of limited extent, it is called
a finite slope.
 A finite slope is bounded by a base
and a top surface.
 Two types of failure of a finite slope
may occur:
 1) slope failure – face failure, toe
failure.
 2) Base failure

4. TYPES OF FAILURE
For toe failure, Df = 1
For base failure , Df >1
where, Df = depth factor

5. The swedish circle method
:
 The sliding surface or the slipping
surface is an arc of a circle.
 The circle corresponding to the
minimum factor of safety is the critical
slip circle.
 Following two cases are considered
1) Analysis of purely cohesive soil
(ø = 0 soil)
2) Analysis of a cohesive frictional soil
(c– ø soil)

6. 1) Ø = 0 Analysis

7. The factor of safety F is given
by
Driving moment, Md
Resisting moment, Mr

8. Effect of tension cranks
When slip is imminent in a cohesive soil, a
tension crack will always develop at the top
surface of the slope along which no shear
resistance can develop.

9. 2) C – Ø Analysis
In order to test the stability of the slope of a
cohesive frictional soil(c-ø soil), trial slip circle is
drawn.
•The forces between the slices are neglected
and each slice is assumed to act
independently as a column of soil of unit
thickness and of width b.
•The weight W of each slice is assumed to act at
its centre.
•A number of trial slip circles are chosen and
factor of safety of each is computed.

11. FRICTION CIRCLE
METHOD
•The friction circle method is useful for the
stability analysis of slopes made of
homogeneous soils.
•This method also assume the failure surface as
the arc of a circle.
•This small circle of radius r sin ø is called friction
circle or ø – circle .
•Force acting on sliding wedge ABDA are:
•1) weight W of the wedge
•2) total frictional resistance R
•3) total cohesive resistance Cm* l mobilised
along the slip surface.

13. TAYLOR`S STABILITY
NUMBER
 The total cohesive force c*l which
resist the slipping of the soil mass
along the slip arc at critical equilibrium
is proportion to the cohesion c and the
height H of the slope.
 Taylor`s stability number Sn

14. •When the slope is steep , the failure surface
passes through the toe , whereas for the flatter
slope , the failure extends below the toe.

15. BISHOP`S METHOD
 Bishop gave a simplified method of
analysis of stability of slope which
considers the forces on the sides of each
slices.

16. •This method also takes into account the pore
pressure acting on the slice.

17. •Equation contain factor of safety in both sides, and
hence these may by solved by trial error.

18. Culmann`s method
 Culmann`s method is used for the
approximate stability analysis of
homogeneous slopes.
 A plane failure passing through the toe
is assumed.
 It is a simple failure mechanism and is
descrined for the purpose of illustration
and for determination of the
approximate value of the factor of
safety.

19. •Let AB be any probable slip plane. The
wedge ADB is in equilibrium under the action
of forces.

20. Where H is the safe height of slope.
The culmann`s method gives reasonable accurate
result for homogeneous slopes which are vertical or
nearly vertical.