Analysis of aggregate pier systems for stabilization of subgrade settlement.

PDFTech ReportFHWA/OH-2014/14134726Subgrade (Pavements)Soft soilsSoil stabilizationVertical supportsSettlement (Structures)Feasibility analysisBenefit cost analysisPavement distressAlternatives analysisOhioOhio. Dept. of TransportationBilgin, \uc3\u2013merArens, KevinSalveter, MarkUniversity of Dayton. Dept. of Civil and Environmental Engineering and Engineering MechanicsUnited States. Federal Highway AdministrationUS Transportation CollectionEvery year, ODOT undertakes numerous pavement patching/resurfacing projects to repair pavementdistress and structural failure due to soft and/or organic soils constituting the subgrade. Other than thetemporary solution of patching/resurfacing, removal of weak soils and replacement with new suitableengineered fill can be used for permanent remediation. However, when problem soils are relatively deepthis method can be too costly. There are various vertical column support methods used for civilengineering structures when soils are not strong enough to support the structure. Although some ofthese methods are utilized by several state DOTs to remediate settlement problems of existingroadways, they were not used in Ohio for this purpose. This study investigated the applicability ofvarious vertical column support systems to improve subgrade and reduce settlements for existingroadways in Ohio. A decision matrix has been developed to identify the feasible methods. Two siteswith ongoing subgrade settlements have been investigated through detailed subsurface investigationsfor possible implementation. Several technically feasible vertical column support methods have beenidentified for these sites. Lifetime cost-benefit analysis performed show that although there are someupfront costs associated with these remediation methods, the vertical column support groundimprovement methods are significantly more cost effective compared to the current practice ofpatching/resurfacing temporary alternative during the project\ue2\u20ac\u2122s lifetime, and can result in significantcost savings to ODOT and roadway users