14-11-2012, 05:07 PM
Critical-State Soil Mechanics For Dummies
critical soil mechanics ppt.ppt (Size: 798 KB / Downloads: 141)
Critical State Soil Mechanics (CSSM
Experimental evidence provided by Hvorslev (1936; 1960, ASCE); Henkel (1960, ASCE Boulder) Henkel & Sowa (1961, ASTM STP 361)
Mathematics presented elsewhere, including: Schofield & Wroth (1968); Burland (1968); Wood (1990).
In basic form: 3 material constants (f', Cc, Cs) plus initial state (e0, svo', OCR)
Constitutive Models, include: Original Cam-Clay, Modified Cam Clay, NorSand, Bounding Surface, MIT-E3 (Whittle, 1993) & MIT-S1 (Pestana) and others (Adachi, Oka, Ohta, Dafalias)
"Undrained" is just one specific stress path
Yet !!! CSSM is missing from most textbooks and undergrad & grad curricula in the USA.
Critical state soil mechanics
Initial state: e0, svo’, and OCR = sp’/svo’
Soil constants: f’, Cc, and Cs (L = 1-Cs/Cc)
Using effective stresses, CSSM addresses:
NC and OC behavior
Undrained vs. Drained (and other paths)
Positive vs. negative porewater pressures
Volume changes (contractive vs. dilative)
su/svo’ = ½ sinf’ OCRL where L = 1-Cs/Cc
Yield surface represents 3-d preconsolidation