Method-of-slices

# Method-of-slices - CEG 4012 Lecture #23 Method of Slices...

This preview shows pages 1–8. Sign up to view the full content.

CEG 4012 Lecture #23 Method of Slices

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Slope Stability by the Method of Slices • Allows for variability of c- slope soils (not homogenous) • Also allows for seepage and external forces • Slope is divided into a series of vertical slices which intersect a trial circular failure surface • The bottom of each slice is straight line and contains only one type of soil:
Slope Stability by the Method of Slices Draw free body diagram of a typical slice i and show the forces acting unit thickness: where: U i = Water pressure force T i = Shear force N i = Normal effective force E i = Normal forces on side S i = Shear force on sides W i = Weight of slice i = Inclination of slice failure plane x i = Width of slice L i = Length of slice failure plane In general: Too many unknowns must make simplifying assumptions . ....

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Geometry for method of slices for each slice must find weight, W i and base angle, i : – can draw slope with slices to scale and measure with scale and protractor – or can use trigonometry: first define the circle center, the circle radius R, the width x i of each, and the horizontal distance, x i , from the circle center to the slice center the volume of the slice is x i h i where h i = height of the slice at its center and h i = R cos α i y i where y i = distance to circle center above slice surface the weight of the slice, W i =  x i h i since
Slice Geometry Example toe circle, i = 45 ° , center above toe, 5' slices, = 120 pcf, R = 40', H = 30', Y =40' for slice 3: x 3 = y 3 = 12.5', x 3 = 5' (40' - 12.5') = 27.5' α 3 = h 3 = R cos α 3 y 3 = W 3 = γ∆ x 3 h 3 = 40’ cos 18.21 ° 27.5’ = 10.5’ Y z 3

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
External Forces in Method of Slices method of slices very flexible: – weight of slice may include both saturated and moist soil – slices may include more than one type of soil – weight of slice should include any water above slice (i.e. calculate total slice weight, the water pressure will be subtracted from N i ) – add vertical external forces to slice weight – add horizontal external forces x moment arm to resisting or driving moment, as appropriate
Fellenius Method (1927) (also known as the Swedish Method) First method of slices developed and presented in the literature. Simplicity of the method: possible to compute factors of safety using hand calculations.

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

## This note was uploaded on 12/14/2011 for the course CEG 4012 taught by Professor Staff during the Fall '08 term at University of Florida.

### Page1 / 37

Method-of-slices - CEG 4012 Lecture #23 Method of Slices...

This preview shows document pages 1 - 8. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online