1279 records matched your query       

04751aam a2200517Ic 4500
001 F8CABD4AB7CA11EC864CB83724ECA4DB
003 SILO
005 20220409010100
008 151208s2015    iauabodfsbt  s000 0 eng d
035    $a (OCoLC)931692997
040    $a UIG $b eng $e rda $c UIG $d SILO
088    $a Iowa DOT Project TR-654
100 1  $a Papanicolaou, A. N. Thanos, $e author. $u University of Iowa.
245 10 $a Development of a Subgrade Drainage Model for Unpaved Roads $c A.N. Thanos Papanicolaou, Filippo Bressan, Christopher Wilson, and Achilles Tsakiris
264  1 $a Iowa City, Iowa $b IIHR--Hydroscience & Engineering, College of Engineering, University of Iowa $c 2015
300    $a vi, 28 pages (34 pages in PDF file) $b illustrations, maps, photos, charts (chiefly color)
536    $a Performed by University of Iowa, IIHR--Hydroscience & Engineering, College of Engineering
536    $a Sponsored by the Iowa Department of Transportation, Iowa Highway Research Board $c Iowa DOT Project TR-654
500    $a October, 2015 -- Technical Report Documentation Page
504    $a Includes bibliographic references (page 18-19)
520 3  $a With over 68 thousand miles of gravel roads in Iowa and the importance of these roads within the farm-to-market transportation system, proper water management becomes critical for maintaining the integrity of the roadway materials. However, the build-up of water within the aggregate subbase can lead to frost boils and ultimately potholes forming at the road surface. The aggregate subbase and subgrade soils under these gravel roads are produced with material opportunistically chosen from local sources near the site and, many times, the compositions of these sublayers are far from ideal in terms of proper water drainage with the full effects of this shortcut not being fully understood. The primary objective of this project was to provide a physically-based model for evaluating the drainability of potential subbase and subgrade materials for gravel roads in Iowa. The Richards equation provided the appropriate framework to study the transient unsaturated flow that usually occurs through the subbase and subgrade of a gravel road. From which, we identified that the saturated hydraulic conductivity, Ks, was a key parameter driving the time to drain of subgrade soils found in Iowa, thus being a good proxy variable for accessing roadway drainability. Using Ks, derived from soil texture, we were able to identify potential problem areas in terms of roadway drainage . It was found that there is a threshold for Ks of 15 cm/day that determines if the roadway will drain efficiently, based on the requirement that the time to drain, Td, the surface roadway layer does not exceed a 2-hr limit. Two of the three highest abundant textures (loam and silty clay loam), which cover nearly 60% of the state of Iowa, were found to have average Td values greater than the 2-hr limit. With such a large percentage of the state at risk for the formation of boils due to the soil with relatively low saturated hydraulic conductivity values, it seems pertinent that we propose alternative design and/or maintenance practices to limit the expensive repair work in Iowa. The addition of drain tiles or French mattresses my help address drainage problems. However, before pursuing this recommendation, a comprehensive cost-benefit analysis is needed.
516    $a Text file in PDF format.
538    $a System requirements: Adobe Acrobat, Adobe Acrobat Reader, or other PDF reading software.
538    $a Mode of access: World Wide Web $u http://publications.iowa.gov/id/eprint/20730
513    $a Final Report
650  0 $a Gravel roads $z Iowa $x Drainage.
650 07 $a Boring $2 trt
650 07 $a Drainage $2 trt
650 07 $a Geotechnical engineering $2 trt
650 07 $a Gravel roads $2 trt
650 07 $a Highway design $2 trt
650 07 $a Hydraulic structures $2 trt
650 07 $a Moisture content $2 trt
650 07 $a Subgrade (Pavements) $2 trt
650 07 $a Subsurface drainage $2 trt
653    $a saturated hydraulic conductivity
700 1  $a Bressan, Filippo Maria, $e author. $u University of Iowa.
700 1  $a Wilson, Christopher, $e author. $u University of Iowa.
700 1  $a Tsakiris, Achilles, $e author. $u University of Iowa.
710 2  $a University of Iowa. $b IIHR--Hydroscience & Engineering, College of Engineering, $e performing body.
710 1  $a Iowa. $b Department of Transportation, $e sponsoring body.
856 40 $a Iowa Publications Online $3 Online Access $z Full report $u http://publications.iowa.gov/id/eprint/20730
941    $a 1
952    $l IAOX771 $d 20240710103146.0
956    $a http://locator.silo.lib.ia.us/search.cgi?index_0=id&term_0=F8CABD4AB7CA11EC864CB83724ECA4DB
994    $a C0 $b UIG