Flooding Compaction

[Joe Grant]

Just enquiring to hear any thoughts on flooding/ponding as a compaction method? It was recently used on a job in Australia with silty sand as the backfill material. The end result was that the soil was extremely stiff. However a lot of underground utilities (ducting etc) have been deformed I am curious whether this may have contributed to this deformation by cause high pressures that do not usually occur or would it be another matter such as excess surface/surcharge loading causing the failures.

 

[L0k]

you have to install the piezometer gauges to monitor the excess ground water and the settlement gauges as well. So you may overcome the failures.

 

[oldestguy]

Interesting subject. Flooding has been around for a long time. However, in my experience any testing that we have done on flooded fill shows that it does not usually meet the specification that we assigned to the job.

On this subject here is a story. I once visited a house construction job in Janesville, WI where the contractor flooded the fill he placed in an attached garage. That garage floor was at an elevation of the original ground. The house had a basement that had its shared wall between the house and garage. Basement was about 8 feet below the garage floor. Soil in the area is generally outwash sand and gravel from a glacier many yers ago. A wind blown silt then developed on that granular material about 4 feet thick. The house had a support beam in its center perpendicular to the wall. The pressure of saturated soil pushed the wall totally in and it dumped a large quantity of that saturated soil into the basement. The support bean, sitting in pockets on concrete walls at each end, got pushed out the of its far pocket about 5 feet by the failing concrete basement wall. When I talked to the contractor about this flooding practice, he said he has done that for many houses and had no problems until then. My response was "I bet you never will do that again".

 

[BigH]

I am not a fan of puddling (flooding) - it is interesting that Vancouver BC does not permit it but their crews in fixing roads and that do . . . however, that said, I have used it once for placing river sand backfill in a narrow space behind a retaining wall. However, the caveat is that we had about a 10 m head and the water drained out - in other words it was seepage pressures that were compacting the backfill, the water was not added and "remained".

 

[Okiryu]

Interesting. I am in Japan and did not know how this type of compaction is called in the US. We use to do flooding compaction for clean sands in trenches and it has been working okay. Also, when I was googling "Flooding Compaction", I found this article from the WisDoT (perhaps OG knows about this):

http://wisconsindot.gov/documents2/research/WisDOT-WHRP-project-0092-11-03-brief1.pdf

 

[oldestguy]

Okiryu

Interesting. I am familiar with one of the writers,but it is now about 55 years since I last saw him. He was one of the engineers that later took over the job I left in '62

 

[Okiryu]

Wow 55 years...thanks for sharing your experiences with us OG...it has been very educative and informative for me..

 

[dirtsqueezer]

I'm not sure flooding compaction would yield a homogenous density. At least I don't see any way to guarantee it. With that in mind, I did do some density tests on bottom ash that was being placed as fill for a ramp in lifts...the local method was to train a fire hose on the drum and give it a few passes. Tests were done with a sand cone (due to the obvious presence of hydrocarbon), and it worked like a charm. That was, of course, with a vibratory roller. We were literally pumping that water into the bottom ash and there was no surface ponding. I don't remember what the gradation was, but I assume it came in with one dominant particle size (so no smaller particles to fill up the pore space). It was a singular experience.

 

[hokie66]

If you dump sand into water in a confined space, the sand will achieve maximum density. But if you pour water into sand, the result is much less predictable. So this technique is not often employed today.

 

[Okiryu]

Just wondering, what is normally conducted in the US to compact clean sands? Here in my area, I still see utilities trenches filled with clean sand and compacted using flooding compaction.

 

[fattdad]

There is a lot of history on dredge-fill dams, which is basically building a dam using puddling - just not called that. I worked on a project 35 years ago, where the contractor used puddling for wall backfill. Never seen it since and would not allow it if I had a say.

f-d

ípapß gordo ainÆt no madre flaca!

 

[EireChch]

Fattdad - completely off topic and a little from left field but what does your sign off text mean? If you wouldn't mid divulging! Ive translated it from Spanish and the last portion means "skinny fat mother"!!

 

[fattdad]

"fat dad is no skinny mother."

It's due to change, but that'd require effort!

f-d

ípapß gordo ainÆt no madre flaca!

 

[dirtsqueezer]

Wouldn't it also be a matter of bb's and bowling balls as far as the transmission of the water? Imagine if those bowling ball pore spaces were filled with bb's? A hydrologist's nightmare it seems to me. Interesting to figure out, though. One could probably come up with a nice gradation curve to model efficient transmission for a flooding scenario.

 

[Ron]

If you have soil classification that would allow some consolidation from flooding, then you likely have a free draining, cohesionless soil. Given this, flooding will get you to a reasonable moisture content near optimum (as it drains). Take advantage of that and compact with minimal effort.