159_CEG 4012 Notes Fall 2011 CEG 4012 Notes Fall 2011

159_CEG 4012 Notes Fall 2011 CEG 4012 Notes Fall 2011 -...

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DF39 -.5lurt.y Method~f Gonstruction: use for caving soils and if groundwater present o slurry (or water) prevents collapse and reduction of capacity o keep water level in shaft above ground water at all times o slurry balances groundwater head, prevents sloughing, and helps replace some of insitu stress lost due to excavation o clay mineral slurries are best - bentonite or attapulgite - sensitive to pH, must control release into environment o organic slurries have light unit weight and depend on positive head to push into and clog soli pores, useless if head reverses, chemically inert and biodegradable o soil/rock cuttings will be suspended in slurry - must be removed ("desand") or will settle out and create sludge on shaft bottom - must control sand content o must limit slurry contact lime (typically < 24-36 hrs) between slurry and soil/rock or
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Unformatted text preview: will form slurry cake with very little capacity (can overream shaft to remove) o slurry must be displaced by concrete - trapped slurry will compromise shaft capacity and integrity - must control viscosity and unit weight of slurry, must use high slump concrete (7"-9") with slow set lime (maintain 4" slump during placement) o sludge buildup on shaft bottom will be trapped near toe during concreting - severely reduces toe resistance and may lose 1-2B side resistance (bullet-nose) - must visually inspect bottom (w/ a camera not a diver), weighted tape penetrates sludge (~) DrIIllnlO c3>'lna 1011 and add II"IT)' Ii . ... CCllary rm ad<'qIl:ue helld and 10 requited dcplJI. (e) Add IJl:mie and Pu"'" eemrnt. ClIldI dliplaced IlulT)' In "''''fI pit. (oil Compk1<'d ,b.rt...
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This note was uploaded on 02/10/2012 for the course CEG 4012 taught by Professor Staff during the Fall '08 term at University of Florida.

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