1 Complex geology slope stability analysis by shear strength reduction Marek Cala, Jerzy Flisiak Department of Geomechanics, Civil Engineering & Geotechnics AGH University of Science & Technology Slope stability Shear strength reduction technique (SSR) The stability of slopes may be estimated using 2D limit equilibrium methods (LEM) or numerical methods. Due to the rapid development of computing efficiency, several numerical methods are gaining increasing popularity in slope stability engineering. The factor of safety (FS) of a soil slope is defined as the number by which the original shear strength parameters must be divided in order to bring the slope to the point of failure. 20 Department of Geomechanics, Civil Engineering & Geotechnics = = trial trial trial trial FS tg arctg FS c c ϕ ϕ
11
Embed
Complex geology slope stability analysis by shear …home.agh.edu.pl/cala/prezentacje/GIS_z5.pdfstability analysis by shear strength reduction Marek Cala, ... Fellenius Bishop Janbu
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
1
Complex geology slope stability analysis by shear
strength reduction
Marek Cala, Jerzy FlisiakDepartment of Geomechanics, Civil Engineering & GeotechnicsAGH University of Science & Technology
� The stability of slopes may be estimated using 2D limit equilibrium methods (LEM) or numerical methods.
� Due to the rapid development of computing efficiency, several numerical methods are gaining increasing popularity in slope stability engineering.
� The factor of safety (FS) of a soil slope is defined as the number by which the original shear strength parameters must be divided in order to bring the slope to the point of failure.
20Department of Geomechanics, Civil Engineering & Geotechnics
==
trialtrial
trialtrial FS
tgarctg
FS
cc
ϕϕ
2
• It’s well known fact that for simple slopes FS obtained from SSR isusually the same as FS obtained from LEM (Griffiths & Lane, 1999; Cala & Flisiak, 2001).
• However, for complex geology slopes considerable differences between FS values from LEM and SSR may be expected (Cala& Flisiak, 2001).
19Department of Geomechanics, Civil Engineering & Geotechnics
Shear strength reduction technique (SSR)
25 m
25 m
hg
45o
Several analyses for the slope with weak stratumwere performed to study the differences between LEM and SSR.
Weak layer 1m thick
18Department of Geomechanics, Civil Engineering & Geotechnics
SSR versus LEM
0 10 20 30 40Distance of weak layer from slope crest
1.4
1.5
1.6
1.7
1.8
1.9
2
FS
Weak layer 1 m thickFLACFelleniusBishopJanbu
25 m
25 m
hg
45o
Hard soil c=75 kPa, φφφφ=30o
Soft soil c=25 kPa, φφφφ=10o
3
Weak layer 5m thick
17Department of Geomechanics, Civil Engineering & Geotechnics
SSR versus LEM
25 m
25 m
hg
45o
0 10 20 30 40 50Distance of weak layer from slope crest
1
1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.8
1.9
2
FS
Weak layer 5 m thickFLACFelleniusBishopJanbu
Hard soil c=75 kPa, φφφφ=30o
Soft soil c=25 kPa, φφφφ=10o
16
Bishop FS = 1.731
FLAC FS = 1.54
20 m
1
m
Department of Geomechanics, Civil Engineering & Geotechnics
SSR versus LEM
4
15
15 m
10
m
10 m
20.918 m15 m15 m
45o
40o
γφ=20 kN/m = 20
c = 10 kPa
3
o
Department of Geomechanics, Civil Engineering & Geotechnics