Construction and Long-Term Performance of Transportation Infrastructure Constructed Using EPS Geofoam on Soft Soil Sites in Salt Lake Valley ,
The Utah Department of Transportation (UDOT) and the Utah Transit Authority (UTA) have made extensive use of EPS embankment for several major interstate, light rail, and commuter railway embankments in Salt Lake Valley, Utah. Constructed between 1998 and 2001, the Interstate 15 Design Build Reconstruction Project involved the widening of interstate embankments within a 27 km narrow corridor and limited right-of-way. Approximately, 100,000 m of EPS fill was placed at various locations to minimize post-construction settlements of deep, compressible lake deposits. This paper presents results of long-term monitoring of EPS fills and comparison with other geotechnologies. Geofoam embankments had the best overall settlement performance of the technologies monitored. Gap closure and deformation of the geofoam embankment due to placement of the load distribution slab and overlying roadway materials was about 1% of the embankment height. In addition, at 3300 South Street, the foundation soil settled about 15 mm due to placement of the embankment and overlying loads. The face of the embankment settled an additional 25 mm in a 5-year period due to additional pressure of a 1.5m toe berm placed at the base of the tilt-up wall. Total post-construction settlement (foundation settlement and geofoam creep) is expected to be about 50 mm at the wall face for a 10-year postconstruction period. The trend of post-construction settlements suggest that geofoam embankments are performing as designed and will meet the 50-year post-construction deformation limit of 1% creep strain. Overview of the I-15 Reconstruction Project The Utah Department of Transportation (UDOT) togeth er with Wasatch Constructors finished the $1.6 billion reconstruction of Interstate 15 (I -15) that runs through Salt Lake City, Utah in 2001 just prior to the start of the 2002 Winter Oly mpics. The interstate embankment was widened from eight lanes to ten general-purpose lan s, plus two high occupancy vehicle lanes, within an existing north-south alignment that runs through the middle of the densely populated Salt Lake Valley. In this area, parts of the I-15 a lignment are located atop extensive deposits of relatively compressible lake sediments. Collateral consolidation settlement along this widened alignment had to be minimized to prevent differenti al settlement damage and subsequent
PERFORMANCE OF A GEOFOAM EMBANKMENT AT 100 SOUTH , I-15 RECONSTRUCTION PROJECT , SALT LAKE CITY , UTAH
The Interstate 15 Reconstruction through Salt Lake City, Utah, involved the widening of highway embankments within a North-South corridor and limited right of way. Previous earth embankments over the deep compressive lake deposits have experienced up to 1400 mm of long-term settlement. The Geofoam Research Center and Utah Department of Transportation placed geotechnical instrumentation in portions of Interstate 15 that employed EPS Geofoam to reduce settlement of critical utilities. Construction and post construction stresses and settlements of the embankment were observed. Preliminary results indicate good settlement performance of the geofoam. Total settlements to date of the foundation soils underlying the geofoam and the geofoam are both on the order of 85 mm. The modulus of EPS 20 in the field has been estimated based on observations, and is generally on the order of 10 MPa, suggesting compressive strength testing of 50 mm cube samples in the laboratory provide a severe underestimate of actual modulus values in service. Deformations of geofoam fills due to seating and gap closure take place during construction. Initial indications of long-term settlement suggest the geofoam treated areas will likely settle less than adjoining sections of earth embankment.
Archaeological Survey of Dangoyama Kofun by 3DGPR
We presented a three-dimensional ground penetrating radar (3DGPR) system for the archeological investigation in a harsh site, where we have to deal with many trees and/or great topographic variations. This system consists of a commercial GPR system with a laser positioning system. With this system, we can move the GPR antenna freely, on which a positioning detector can record accurate position for each GPR data trace. We applied our 3DGPR system at Dangoyama Kofun, a burial mound, in Fukushima prefecture, Japan. A lot of trees and bushes covered the survey area and cannot be cut. We acquired six datasets in two days in this area. We successfully imaged the boundary between the original surface of the burial mound and the covering soil clearly at about 0.3 m depth around the mound. Furthermore, we found some strong reflections appeared at 0.8 m depth in the top area of the mound, which can be from the artificial parts of the burial mound. The results would greatly aid the following archaeological excavation. In addition, we compared the non-interpolated depth slice with interpolated depth slice at same position and demonstrated that the interpolation process on threedimensional GPR data may introduce some artifacts which might mislead our interpretation.