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
REMPLACEMENT PARTIEL DE ARGILE MOLLE «TINA» DANS LA PLAINE, SINAÏ, EN ÉGYPTE SOUS PAR SEMELLES GEOFOAM
The soil of Tina Plain in Sinai is classified as very soft to soft clay. Buildings on this type of soil experience excessive settlements. Thus, deep foundations are considered as the most suitable type to support building loads. Another option is to use a light-weight material as a partial replacement under footings to decrease the stress on soil and consequently reduce the expected settlements. Expanded polystyrene (EPS) Geofoam blocks have been used as a light-weight-fill material under lightly loaded footings on soft clay soil to reduce settlements. An experimental study has been performed to assess the behavior of footings resting on soft clay, improved with EPS geofoam partial replacement. The experimental study of this research is divided into two parts; the first part is a laboratory program to investigate the mechanical properties of Geofoam. The second part is a field load testing program on small-scale model isolated footings founded on soft clay partially replaced by Geofoam blocks. Square and rectangular footings of dimensions 20 x 20 cm, and 20 x 30 cm respectively are loaded with an equivalent pressure of 50 kPa. The loading is performed stepwise with each step forming one fifth of the total applied load. The Geofoam thickness is varied from 50 mm to 300 mm and the width is varied from 200 mm to 500 mm. The software ABAQUS is used to model and verify the experimental results. Results showed that the geotechnical properties of Geofoam are similar to that of stiff or very stiff soil. Results also showed that replacement of Tina Plain soft clay by Geofoam could be used efficiently to limit foundation settlements of lightly loaded footings within tolerable values.
BEHAVIOR OF EXPANDED POLYSTYRENE BLOCKS
An innovative construction material, expanded polystyrene blocks (EPS blocks), has been introduced in geotechnical engineering in recent years. Because of its extremely light weight and ease in handling, it provides an alternative to conventional backfill, embankment earth materials, and lightweight fill. It is anticipated that the use of EPS blocks in the construction industry may result in substantial cost savings. New applications of EPS blocks as structural elements are expected to emerge as engineers learn more about this material. A series of laboratory tests were conducted to determine the mechanical properties of EPS blocks. Included are the results of undrained triaxial tests with volume change measurements for the determination of a constitutive relationship, a repeated loading test, punching shear tests, and a long-term creep test. The test results show several distinctive material characteristics, including a bilinear stress-strain relationship and negative Poisson's ratio that are not common in conventional construction materials. The results of this study can readily be incorporated in detailed analyses of various geotechnical engineering structures constructed with EPS blocks.