Levee Open Cut - Emergency Closure
Levee Open Cut - Emergency Closure
(OP)
For a levee constructed of cohesive fill (lean clay) over lean clay native subgrade conditions, should drained conditions be considered for an emergency sheet pile closure? It would be expected that a flooding event would be rather short; but at what point should drained analysis be considered in conjunction with undrained conditions?





RE: Levee Open Cut - Emergency Closure
As far as how long it takes for conditions to change from undrained to drained, depends on the loading and how quickly the soil can drain. There are often thin horizontal layers of sand and silt in lean clay deposits in river valleys; this often leads to the clays draining much quicker than expected.
Mike Lambert
RE: Levee Open Cut - Emergency Closure
RE: Levee Open Cut - Emergency Closure
Basically, the open-cut excavation in the levee is sloped on each side (i.e. V-Notch). If an emergency closure were needed, the contractor would close the notch by driving sheet piles the full length of the open-cut (about 125-ft) and support them with vertically driven H-piles.
RE: Levee Open Cut - Emergency Closure
Again, I would say that it should be checked both ways.
How high is the levee? Also, you will need to check seepage beneath and through the sheet piles. Remember, a single line of sheet piles will leak like a sieve.
Mike Lambert
RE: Levee Open Cut - Emergency Closure
My intuition was that both conditions should be checked; although, I mostly see 'undrained' conditions referenced
for temporary shoring in clays. However, if installed in an emergency, flood waters could persist for days...
possibly weeks....so I like the idea of checking both conditions.
Not sure if leakage would be a 'serious' issue........I've not seen this in application.
RE: Levee Open Cut - Emergency Closure