FREDLUND边坡稳定未来讲义.ppt

1 0 2 0 1 0 0 6 0 5 0 4 0 3 0 9 0 8 0 7 0 1 1 0 7 0 5 0 6 0 4 0 1 0 2 0 3 0 8 0 F s ( m = 0.33) F s ( m = 0 . 4 8 ) GLE (F.E. Function) s Method X Y R Factor of safety G L E ( F . E . Function 5 8 . 0 5 8 . 5 4 0 . 2 2 . 3 0 3 F s ( m = 0 . 3 3 ) 5 2 . 5 5 0 . 5 3 1 . 8 2 . 2 5 9 F ( m = 0 . 4 8 ) 5 1 . 5 5 1 . 5 3 1 . 0 2 . 2 7 3 Location of the Critical Slip Surface for a Half Submerged Slope where the Soil Properties are c = 40 kPa and f = 30° x - Coordinate (m) y - Coordinate (m) Conclusions from Step 1 Forward Normal and Actuating Shear stresses from a finite element analysis appear to provide a more reasonable representation of the stress state in a slope The Enhanced Limit method by Kulhawy (1969) appears to open the way to simulate more complex slope stability problems Enhanced Limit methods can readily be used in routine engineering practice Global factors of safety appear to be essentially the same for most simple slopes Selection of Poisson’s ratio has some effect on the Enhanced Limit factor of safety Factors of Safety appear to differ slightly for: Low cohesion values High angles of internal friction How do the Results from Enhanced Limit Methods Compare to Limit Equilibrium Methods? Local Factors of Safety can also be computed by the Enhanced Limit Method Second Step ForwardQuestion: Is it possible for the computer to determine the Shape of the critical slip surface? Is it possible for the computer to determine the Location of the critical slip surface? Improvement on Shape and Location Ha and Fredlund 2002 Force and Moment Limit equilibrium Factors of Safety for a “Sliding Block” type slip surface Moment limit equilibrium analysis Force limit equilibrium analysis Lambda, l Factor of safety Krahn 2003 Extensions of Methods of Slices toThree-dimensional Methods of Columns Hovland (1977) – 3-D of Ordinary Chen and Chameau (1982) – 3-D of Spencer Cavounidis (1987) – 3-D Fs 2-D Fs Hungr (1987) – 3-