seep/W sand boiling
seep/W sand boiling
(OP)
Hi all,
I have a question regarding analysis of so called 'sand boiling' under the embankment. On existing embankment there is an issue where water appears on the bottom of the slope due to internal erosion of sand in upper layers, below is gravel. Any ideas how to model this in seep (geostudio)? which BC to use to simulate this. I've tried to do something and I can obtain hydraulic gradient which can be considered as cause of sand boling, but when I model an interface which should simulate cutoff, these gradients are even larger. Any ideas?
Thanks!
I have a question regarding analysis of so called 'sand boiling' under the embankment. On existing embankment there is an issue where water appears on the bottom of the slope due to internal erosion of sand in upper layers, below is gravel. Any ideas how to model this in seep (geostudio)? which BC to use to simulate this. I've tried to do something and I can obtain hydraulic gradient which can be considered as cause of sand boling, but when I model an interface which should simulate cutoff, these gradients are even larger. Any ideas?
Thanks!





RE: seep/W sand boiling
Sand boils occur when the water is confined by a surficial layer causing increased pressure below the surficial layer. When the water finds a weak spot in the surficial layer and escapes, a boil can form.
You describe a wet area on the slope and indicate that it is due to flow through the embankment. This is a seepage issue, not a sand boil issue.
I recommend that you get with someone who has more experience with type of analysis so they can help you understand the differences.
good luck.
Mike Lambert
RE: seep/W sand boiling
RE: seep/W sand boiling
RE: seep/W sand boiling
RE: seep/W sand boiling
http://deltafarmpress.com/government/corps-enginee...
RE: seep/W sand boiling
The last reference deals with a way to correct the sand boil problem by wells, other than using the sand bag surround technique.
http://etd.lsu.edu/docs/available/etd-0403103-1111...
http://web.stanford.edu/~meehan/flood/mech.html
http://ussdams.com/proceedings/2012Proc/659.pdf
http://www.dailyjournal.net/view/story/86549eb022d...
RE: seep/W sand boiling
To help those who use the program, why don't you copy the cross section of your program set up diagram and post it for them to comment on.
My cursory viewing of the WEEP W instructions would lead me to believe it would be simpler for you to forget it and go the old fashoned way and draw that flow net.
You will note that the referenced documents have checked their results against WEEP W, yet they go about a more straight forward approach.
RE: seep/W sand boiling
RE: seep/W sand boiling
RE: seep/W sand boiling
I can't tell enough about the gradients from the posted images to offer any advice on how the gradients are changing from before and after. I would caution you against using the gradients calculated by the software and instead manually calculate the gradients across the sand layer by hand using the constant head contours.
Based on these images, the easiest way to control the exit gradients and seepage would be to install either a trench drain or a series of relief wells just off the landside toe of the embankment. Either would allow you to collect and transport the seepage a way from the structure and would provide a safe exist for the excess seepage head.
Mike Lambert
RE: seep/W sand boiling
Boiling is the result of exceeding the critical gradient.
f-d
ípapß gordo ainÆt no madre flaca!
RE: seep/W sand boiling
RE: seep/W sand boiling
RE: seep/W sand boiling
I stand by my advice above.
Mike Lambert