148_CEG 4012 Notes Fall 2011 CEG 4012 Notes Fall 2011

148_CEG 4012 Notes Fall 2011 CEG 4012 Notes Fall 2011 - (a...

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DF28 Wave Equation Analyses: SOIL 1 R u (.) F= ~ (/) ci,lo. -""-'OU~A~KE=----- DISPLACEMENT RD III Js. vp •Rs -.--PILE---~ 8m.lth Wave Eqadon Model. (Goble .nd .R ..... WI) ACTUAL SYSTEM O MODEL ----r= LENGTH L ELEMENT MASS M I RAM MASSL-J· AREA A SPRING 1 MODULUS E I'l-. ......... fANVIL t~'---. .{' ..,~W~~ ~HEUfET=--::;;;:;;;;:!~ c:::J • PILE CUSHION ~ u SOIL RESISTANCE ~ ~ o o theory for transmission of one-dimensional compression wave first proposed i)2 u E i)2 u by D.V. Isaacs (1931): at 2 = P i) z 2 (remember Terzaghi 1-D consolidation?) o computational method generally attributed to E.A.l.Smith (1951, 1960) o finite difference solution o pile, hammer, and cushions modeled with discrete elements o static soil resistance modeled with bilinear springs (the static pile capacity) o dynamic soil resistance modeled with linear dashpots
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Unformatted text preview: (a linear function of the penetration velocity and a damping constant) o soil model is crude but effective o modern computers have improved our computational capability (thank you 18M) o first program from Texas (TIl), followed by FHWA research (WEAP), now marketed by Pile Dynamics, Inc. as GRLWEAP o possible to do rational parametric studies for different pile and hammer configurations o especially useful for drivability studies and pile stress predictions o still needs refinement in areas of dynamic stiffness (1.1 to 1.5 times static stiffness) and correlation of standard soil properties to spring-dashpot model...
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