Designing an Excavation with an Artesian Condition

[aquazac]

Fellow Geotechs,

New to the site here so exercise patience. I am looking for a good technical reference(s) for designing excavations when an artesian condition is present. Essentially, I am most concerned with bottom blowout (i.e., uplift/rupture of the aquatard from artesian pressure) and how to account for the artesian pressure when calculating basal heave. Furthermore, if anyone is aware of some good case histories were bottom blowout and/or basal heave have created failures, unworkable conditions, or general construction difficulties, please share. All suggestions are greatly appreciate.

I did a brief search through existing threads and came up empty. Please notify me of any existing discussion related to this topic. Thanks.

 

[molerat2210]

US Steel Sheet Pile Design Manual provides guidance on cofferdam design and addresses some of the bottom boiling and heaving issues.

 

[USGeotech]

Also, always remember first principles. The lateral stress at any location or depth is equal to the vertical effective stress multiplied by the appropriate pressure coefficient. When calculating the vertical effective stress, you must use the ACTUAL anticipated pore pressures. Since the actual pore pressures are dependent on the dewatering system, the cofferdam designer must understand every stage of the excavation and dewatering plan.

 

[motorbiketocrank]

Well, although it's a little old, there's some brief discussion in the free Corps of Engineers technical manual

http://www.wbdg.org/ccb/DOD/UFC/ufc_3_220_05.pdf

Also, I'm not positive how much discussion there is of heave but a very good overall groundwater/dewatering reference is

http://www.amazon.com/Construction-...9438/ref=sr_1_1?ie=UTF8&qid=1337642224&sr=8-1

 

[dgillette]

Your dewatering specs must include a backup engine-generator set ready to go immediately (and tested weekly), in case the primary power is lost!