vertical sand drain material
vertical sand drain material
(OP)
Hi,
A Specification for vertical sand drain says that sand should be placed into holes as:
"Sand shall be placed to attain a relative density of 90 %".
Is it necessary to define this requirment?
How to ensure this requirment is achieved, what test?
thanks
CD
A Specification for vertical sand drain says that sand should be placed into holes as:
"Sand shall be placed to attain a relative density of 90 %".
Is it necessary to define this requirment?
How to ensure this requirment is achieved, what test?
thanks
CD





RE: vertical sand drain material
Richard A. Cornelius, P.E.
WWW.amlinereast.com
RE: vertical sand drain material
Dicksewerrat
-it is vertical sand drain there is no wrapping at all.
- yes, there is gradation spec for backfill material.
RE: vertical sand drain material
RE: vertical sand drain material
That point aside, how is anyone going to test a vertical sand drain? All but the very top is many feet below grade.
To you question is it necessary to specify a compaction in a vertical drain?, I have never seen it done. All that would likely be needed would be to compact the surface following installation of the drains and before construction of the remaining structure, which is probably already required as part of the site preparation.
RE: vertical sand drain material
thank you for your comments.
-The vertical sand drains is to be installed 20m deep in firm becoming soft clay.
-the reason behind 90% relative density is to prevent any possible squeeze of clay inside the hole and ensure the column of sand is there in full section ...the gradation spec is 0-3% of fines and placement of sand to 90% relative density, should not impcat permeability...previous experince shows possible placement to this requirement for stone column material (more coarse material).
- measuring the mass of sand placed with known hole volume should provide information about relative density...determination is to follow ASTM D4253 and D4254.
Yet to look in the ref you gave cvg
thanks
CD
RE: vertical sand drain material
RE: vertical sand drain material
-the hole to be used is 450mm, holes up to 300mm in dia had experienced clay squeeze in bottom.
-the plan is to use roding or jetting to achieve compaction.
- from yours and other reply it seems that 90% relative density requirement on high side...Any other figure beside 70% of cvg?
thanks
RE: vertical sand drain material
RE: vertical sand drain material
RE: vertical sand drain material
RE: vertical sand drain material
CD