Poor Subgrade Road Section - Creative Ideas/ Experiences Needed!
Poor Subgrade Road Section - Creative Ideas/ Experiences Needed!
(OP)
I would GREATLY appreciate any help with the following situation:
I have a poor section of road that I need to get a decent life span out of, but the muck and soils are terrible. It is a 1100 FT section of 5000 ADT road. The water table is very high and the marl and peat run from about 8'-33' deep. The road has been repaved and buried 3 times because it continues to sink.
I am looking for a good solution and cost is not too much of a factor. We have a ton of slag we would like to use if possible. Here are 3 ideas I have had so far.. please let me know if you have used any of these or know someplace that has or if you have any other comments or ideas...
1. remove the pavement. place slag in a sewed geotextile fabric to create a slag envelope. place sand/aggregate over the slag and concrete the top.
2. create a corduroy road joined with stainless steel wire. place concrete powder over the corduroy and then aggregate and asphalt.
3. drive steel plates along the sides. join the plates toward the bottom with a stainless steel line and pull the bottoms together to form a "V" with the road being at the top of the "V", kind of like a bottle cork.
4. try to find large pieces of syrafoam to build the road on.
Thanks!
I have a poor section of road that I need to get a decent life span out of, but the muck and soils are terrible. It is a 1100 FT section of 5000 ADT road. The water table is very high and the marl and peat run from about 8'-33' deep. The road has been repaved and buried 3 times because it continues to sink.
I am looking for a good solution and cost is not too much of a factor. We have a ton of slag we would like to use if possible. Here are 3 ideas I have had so far.. please let me know if you have used any of these or know someplace that has or if you have any other comments or ideas...
1. remove the pavement. place slag in a sewed geotextile fabric to create a slag envelope. place sand/aggregate over the slag and concrete the top.
2. create a corduroy road joined with stainless steel wire. place concrete powder over the corduroy and then aggregate and asphalt.
3. drive steel plates along the sides. join the plates toward the bottom with a stainless steel line and pull the bottoms together to form a "V" with the road being at the top of the "V", kind of like a bottle cork.
4. try to find large pieces of syrafoam to build the road on.
Thanks!





RE: Poor Subgrade Road Section - Creative Ideas/ Experiences Needed!
RE: Poor Subgrade Road Section - Creative Ideas/ Experiences Needed!
Here is a link to one vendor's website for general information (plenty other vendors have suitable products, too)
http://www.geotextile.com/tech/tech.htm#guide
Take a look at page 2 & 3 of Tech Note #1
http://www.geotextile.com/tech/pdf/t01a.pdf
www.SlideRuleEra.net
RE: Poor Subgrade Road Section - Creative Ideas/ Experiences Needed!
You could consider using shredded tyres as a lightweight fill replacement (if you have abundant trees, like in British Columbia, hog fuel or tree bark would be an alternative). Say you can remove 3.5m of the road embankment (pavement and 3m) - then replace with shredded tyres at 40% of the weight of the fill removed - you will effectively unload your site by about 500 psf or so (rounded) - while you might get some settlement of the tyre shreds, the unloading should effectively stop the catch 22 situation of adding fill and settle; add more fill and settle, etc. Expanded shale would also be a possible material to consider - or a limited thickness of geofoam.
RE: Poor Subgrade Road Section - Creative Ideas/ Experiences Needed!
RE: Poor Subgrade Road Section - Creative Ideas/ Experiences Needed!
I found that it is also helpful to remove about 2' of the "bad Material" and replacing it with a good clay, then your geofabric, and then sub-base and so forth. Essentially design a boat for your road....this is the cheap route and in both situiations I have had heavy truck traffic for several months before the roads were turned to service roads that now have little traffic.
RE: Poor Subgrade Road Section - Creative Ideas/ Experiences Needed!
RE: Poor Subgrade Road Section - Creative Ideas/ Experiences Needed!
RE: Poor Subgrade Road Section - Creative Ideas/ Experiences Needed!
Thanks for the link!
RE: Poor Subgrade Road Section - Creative Ideas/ Experiences Needed!
RE: Poor Subgrade Road Section - Creative Ideas/ Experiences Needed!
Other methods (again costly) are to use stone or grout piles. http://www.laynegeo.com/index.html
http ://users.a delphia.ne t/~jdwoote n/spider_g oes_by.gif
RE: Poor Subgrade Road Section - Creative Ideas/ Experiences Needed!
RE: Poor Subgrade Road Section - Creative Ideas/ Experiences Needed!
Good Luck
RE: Poor Subgrade Road Section - Creative Ideas/ Experiences Needed!
Undercutting and replacing with select material (i.e. - cherty clay, granular fill, riprap, etc.) is a traditional fix, however, if the contractor gets caught in the middle of undercutting by rain or other weather calamity, a poor subgrade situation will typically become worse. Lime treatment is also a quick remedy, however, with the high water table that you indicated, the lime will eventually leach out of the treated soil. With these and other "surficial" treatments, long-term settlement (as indicated by BigH) is still a problem. SlideRuleEra has a good idea to use geotextiles' separator function to ensure the long-term integrity of your "good" material by keeping out the "bad" material. However, I think you should go a step further and design this roadway using the methodolgy for capping lagoons (see - http://fi
Using this methodology should address long-term settlement (i.e. - through subgrade reinforcement, stabiliztion, and separation)and provide a construction platform for the contractor. After you have constructed this pavement subgrade, any pavement section designed using your local pavement design methodology should provide satisfactory long-term performance.
RE: Poor Subgrade Road Section - Creative Ideas/ Experiences Needed!
Remove the unsuitable soil to a acceptable depth and replace with either rubber tires or lightwieght styrofoam and float your road over the unsuitable soils. If you need to run utilities, I would suggest that you us a deep foundation system to prevent future breaks.