详情

Implementation Using Geofoam for Bridge Approach Slabs and Roadway Embankments

项目名称：	Implementation Using Geofoam for Bridge Approach Slabs and Roadway Embankments
摘要：	Texas Department of Transportation's (TxDOT's) Fort Worth District installed a novel lightweight fill material, Expanded Polystyrene (EPS) geofoam, as part of a rehabilitation of the US 67 bridge over SH 174 in Johnson County. The bridge embankment constructed in 1995. is approximately 40 ft. high. Readily available moderate plasticity clay soil has been adopted as the fill material. For the past 16 years, the approach slabs at each end of this bridge had experienced more than 17 in. of settlement. The District funded a rehabilitation project to remove the modular block walls underneath, construct 3:1 slopes, repair bridge beams, and remove and replace 150 ft. of approach slab and pavement on each end. EPS geofoam was selected due to its lightweight and high compressibility attribute. The weight of EPS geofoam utilized is only a small fraction of soil that was excavated. Geofoam was designed to replace 6 feet of the embankment from the bottom of the bridge abutment upward. The additional 2 ft. remaining at the top of pavement was constructed with a 10 in. layer of item 247 flexible base, 4 in. of item 3224 Type. B hot mix, and 10 in. of CRCP concrete pavement. This rehabilitation work started in January 2012 and was completed in the following month (February 2012). This area was instrumented with four (4) horizontal inclinometers and four (4) pressure cells to monitor the settlement behavior and pressure response of the embankment in relation to the dead load of the overlying pavement structure, live traffic loading, embankment settlement, and pressure against the abutment and wingwalls. After the completion of installation in February 2012, University of Texas, Arlington (UTA) research team conducted field performance monitoring at regular interval. It can be observed from the horizontal inclinometer data that during the three years after opening to traffic, less than 1.5 in. (38 mm) of post-construction vertical displacement [settlement] has occurred. No visible deformation or bump is observed in the concrete pavement surface. However, soil erosion at shoulder and a 3 in. (76mm) differential settlement at the pavement has been observed and documented on the south side slope of the embankment. it appears that the slope soil is creeping laterally away from the roadway thereby leading to this differential settlement at the pavement and wing wall edge. Continual wet soil exists at the end of a drain line installed at the end of the wing wall during construction and draining down the slope. The origin of this water is still unknown. Due to the continual soil movement and water draining from under the approach slab, the influencing factors contributing to settlement of geofoam installation are not yet identified. Additional data collection is desired in order to evaluate the longer-term performance of the EPS geofoam in this embankment. Hence, continued site visits for data collection need to be conducted for at least 5 to 6 years. Long-term performance data will also help in the formulation of design charts for future use of EPS geofoam in other projects.
状态：	Completed
资金：	$336370
资助组织：	Texas Department of Transportation
项目负责人：	Adams, Joe
执行机构：	University of Texas, Arlington
主要研究人员：	Puppala, Anand J
开始时间：	20150429
预计完成日期：	0
实际结束时间：	20170831