Driveway thru wet area

I took out all the topsoil and filled the drive with about 3' of sand, then top it with 8" of road gravel. It seemed hard as a rock, but then I had about 15 gravel trucks go in and out and a section of the drive turned into jello. Is there anything I can do to fix this?

 

[TAC]

Does the problem appear to be with the original subgrade or with the new fill? What kind of soil is the subgrade? Is the groundwater table near the ground surface?

 

It seems to be with the new fill sand. Ground water is about 2' to 3' below the surface of the drive. I think with all the trucks going in and out it pulled some water to the surface. I'm in Michigan and and there has been soom rain also. I was thinking about adding some crushed concrete.

 

[elizasue1]

Try utilizing a geotextile fabric (10 oz or heavier) between the sand and gravel layer. This material will allow the water to pass through but the gravel will remain in place. Without knowing any more information about the site it would be difficult to make any other suggestions. Good Luck.

 

[TAC]

Assuming that the problem is due to pumping it would probably be beneficial to install an edge drain along the drive. Note that you will need someplace to outlet the drain. Once the sands are dewatered they should restabilize. If the sand has a lot of silt and clay in it it may drain relatively slowly and some stabilization may be needed to get you opperating on it right away. Geotextile and crushed concrete would probably work.
As discussed in the elizasue1's post it is difficult to make a recommendation without seening the site and determining the nature of the problem.

You could bring in a geotechincal engineer to take a look and make a recommendation. Our company has an office in Toledo and does work in N.W. Ohio and S.W. Michigan. We'd be happy to help if your located near us, otherwise, a good contractor or structural engineer can recommend a geotech firm thats closer to you.

 

[Jim6758]

You might also consider a geo-grid with some crushed stone on top. If the water table is high, you will need to construct an edge drain as previously recommended.

 

[MRM]

Be sure to compact the sand fill in lifts. I suspect that this was one of the main causes for the "jello" effect you described. The trucks pulled the water upwards and may have also partially liquefied the new, loose, fill soil. Three feet of relatively uncompacted fill has a lot of potential for settlement, especially from a dynamic or vibrating source such as several heavy trucks running over the area. It is also a good idea to provide some compactive effort to the surface gravel layer as well using a roller or dozer.

One question, did the soft zone seem to "tighten" back up after the trucks were done with their jobs?

 

[n3rei]

Hi!
I have had a similar problems in the old farm areas of Delaware. Delaware is by nature sandy. The problem first arose when a stabilized construction entrance seemed to do the jello role. Our soils engineer could not confirm a high water table nor was the soil bad. Further investigation shawed a hard pan layer which would not let the water infiltrate. The solution for the entrance was to lay Geo-Grid and stone. Worked great. With your high water table this should work fine for you also. The rest of our Site we just broke through the 3" thick hard pan @3' depth and foundations and infiltration areas worked fine.