1. WELCOME TO Ye-S ACADEMY

2. FRICTION CIRCLE METHOD COLUMAN’S AND COLOUMB’S THEORY
SYABILITY OF SLOPES
FRICTION CIRCLE METHOD
COLUMAN’S AND COLOUMB’S THEORY

3. Stability of Slopes

4. z σz σ τ B A D C Normal and tangential stresses are, σ and τ b b cos i
τ is tangential stress acting along plane CD, tries to slide the soil i σ
Where as stress τf is resisting
the slide of plane CD C τ
Factor of Safety

5. Stability Number
We have Factor of Safety for cohesive soils as
We know
Substituting

6. Stability of Slopes
Stability of finite Slopes can be analyzed by following methods
Swedish circle method
Friction circle method
Bishop’s method

7. O r C B r W A b b Total Driving Force is W1 W2 W3 W4 N1 W5 W1 W6 T1 W7

8. To find out Σ N and Σ T following rectangles are drawnb b

9. P Q Factor of Safety Curve Critical Circle point
Least Factor of Safety Q

10. FRICTION CIRCLE METHOD
This method also assumes the failure surface as the arc of a circle.
In this method a concentric circle with P as center and “r sinφ” as radius is drawn.
When a tangent is drawn to this circle which will cut the failure circle at an Obliquity φ.
Other way, if a line is drawn at an obliquity angle φ, from failure surface representing reaction Δ R, then this line will be tangent to the small circle drawn at P
This small circle is known as “Friction Circle”

11. Consider a slope ABC, and a slip surface AC which is a part of a circle with radius “r”
Draw a line F1E1 which is tangent to the circle and cuts failure surface at angle φ. F2 F2 G P G
r sin φ F1 F1 B C
Friction Circle φ E2 φ A E1
Similarly draw line F2E2

12. R Tangent to friction circle
In order to know magnitude of and R, force triangle is drawn as shown. R W
In this force polygon (triangle) W is known to us and hence and R can be calculated.
Then Factor of Safety is calculated as
Parallel to chord AC
Where C is cohesive strength and Cm is Mobilised cohesive strength

13. Area of N-Rectangles = 14.4sq cm
In order to find the factor of safety of d/s-slope of an earth dam, during steady seepage , the section of the dam was drawn to a scale of 1 cm = 4 cm, and the following result obtained on a critical sip circle.
Area of N-Rectangles = 14.4sq cm
Area of T-Rectangles = 6.4sq cm
Area of U-Rectangles = 6.9sq cm
Length of Arc = 12.6 cm
Laboratory test results have furnished angle of resistance as 26 degrees and 19.5kN/m2 for cohesion. Determine the factor of safety of the slope. Unit weight of soil = 19 kN/m3

14. Scale 1 cm = 4 cm, i.e x= 4

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1. EXPLAINS ALL DEFINITIONS AND CONCEPTUAL
MEANINGS
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2. DERIVES ALL FORMULA WITH ANIMATED
FIGURES TO KNOW BASICS
3. CONTAINS VARITIES OF NUMERICAL WITH
GOOD NUMBER OF ANIMATED FIGURES
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