Geofoam Applications in the Design and Construction of Highway Embankments (2004)

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10-1 CHAPTER 10 TYPICAL DESIGN DETAILS FOR EPS-BLOCK EMBANKMENTS Contents Introduction.................................................................................................................................10-1 Design Details for Trapezoidal EPS Embankments ...................................................................10-2 Design Details for Vertical EPS Walls .......................................................................................10-3 Design Details for Bridge Abutments.........................................................................................10-4 Utility And Roadway Hardware Details .....................................................................................10-4 Design Details for Protective Load Distribution Slab ................................................................10-6 Anchoring Details for Hydrostatic Uplift ...................................................................................10-6 Installation of EPS-Block Geofoam............................................................................................10-7 References...................................................................................................................................10-7 ______________________________________________________________________________________ INTRODUCTION The main objective of this report is to facilitate the use of EPS-block geofoam in roadway applications. To accomplish this objective a provisional design guideline for roadway embankments is presented in Appendix B of this report. However, to complete this objective a material and construction standard as well as construction drawings need to be presented so the design engineer can distribute the EPS-block geofoam design for bidding and construction. An appropriate material and construction standard for geofoam embankments is included in Appendix C. As a result, the remaining aspect to facilitate the use of geofoam in roadway embankments is to provide designers with typical construction drawings and details to aid preparation of bid and construction documents. This chapter presents typical construction details for traditional, i.e., trapezoidal (see Figure 3.4(a)) geofoam roadway embankments and vertical EPS embankments or walls (see Figure 3.4(b)). The construction details presented in this chapter

10-2 were obtained from actual geofoam construction drawings from projects throughout the United States and can be used as a guide for developing site-specific drawings or details. The details presented relate to a variety of geofoam issues, such as, configuration of the EPS blocks, inclusion of utilities and roadway hardware, construction of a load distribution slab over the EPS, and anchoring of the EPS blocks to resist hydrostatic uplift. In some cases the figures that have been reproduced use either all Système International d’Unités (SI) or all inch-pound (I-P) units. Those figures have not been revised to show both sets of units. However, Appendix F presents factors that can be used to convert between SI and I-P units. An important aspect of constructing a geofoam embankment is preparation of the foundation soil prior to block placement. No detail illustrating this important point was located so it is described before presenting the details. Before placement of the EPS blocks, the foundation soil should be prepared to facilitate placement and alignment of the blocks. This is sometimes difficult with soft foundation soil because the soil can displace as construction personnel traverse the site. Therefore, the alignment of the blocks should be identified prior to placement and a working platform consisting of soil or a geosynthetic may be required. This preparation is also required for earthen embankments and should not increase the cost of the geofoam embankment. DESIGN DETAILS FOR TRAPEZOIDAL EPS EMBANKMENTS Figure 10.1 presents a typical design cross-section for a roadway embankment consisting of only EPS-block geofoam construction over peat. This cross-section was obtained from the reconstruction of Indiana State Route 109 in Noble County (1), which is described in detail in Chapter 11. It can be seen that the blocks are overlain by an aggregate subbase and a flexible pavement system. Figure 10.2 presents a design cross-section for a roadway embankment that utilized both EPS-block geofoam and on-site earth material. This cross-section was obtained from the construction of an emergency escape ramp for Highway H-3 on the Island of Oahu in Hawaii (2). This case history is also described in more detail in Chapter 11. This cross-section

10-3 illustrates that use of EPS-block geofoam above on-site basalt tunnel mine spoil that is geosynthetically reinforced to increase stability. This cross-section shows that geofoam can be used with on-site material to produce a cost-effective design for roadway embankments. Figure 10.1. Trapezoidal geofoam embankment detail (1). Figure 10.2. Trapezoidal embankment using geofoam and on-site material (2). DESIGN DETAILS FOR VERTICAL EPS WALLS Figure 10.3 presents a typical design detail for a vertical roadway embankment consisting of only EPS-block geofoam. This detail was obtained from the Interstate-15 Corridor Reconstruction in Salt Lake City, Utah and was prepared by the Utah Department of Transportation (3). The detail shows a number of important aspects for construction of vertical EPS walls including the excavation of the existing ground to form a base for the geofoam wall and prevent frost heave, installation of a drainage blanket under the geofoam blocks, and placement of the geofoam blocks against a precast wall panel. This detail also illustrates the use of a geomembrane to protect the geofoam from hydrocarbon spills and a concrete pavement system above the granular subbase. Other important details in Figure 10.3 include a storm drain and flowable backfill to seal around the storm drain pipe, the inclusion of a traffic barrier (see Figure 10.4) and a concrete load distribution slab over the geofoam (see Figure 10.4). Figure 10.4 presents a detail for the anchoring of the traffic barrier to the precast wall panels and construction of a concrete load distribution slab over the EPS. It can be seen that the load distribution slab consists of No. 19 steel reinforcing bars at a spacing of 254 mm (10 in.). Figure 10.5 presents typical details for fabrication of the precast concrete wall panels for the vertical EPS wall with options for reinforced concrete and prestressed concrete panels. Figure 10.5 also presents a typical detail for the joints of the wall panels. Figure 10.3. Construction detail for a vertical EPS wall (3). Figure 10.4. Detail for traffic barrier and load distribution slab(4). Figure 10.5. Detail for precast concrete wall panels for a vertical EPS wall (5).

10-4 DESIGN DETAILS FOR BRIDGE ABUTMENTS This section of Chapter 10 presents construction details for the use of geofoam in bridge abutments. This is an important application of geofoam and involves drawings for both the embankment/abutment interface and the pavement system overlying the geofoam. Figure 10.6 presents a typical design detail for a pile supported bridge abutment from the Interstate-15 Corridor Reconstruction in Salt Lake City, Utah (6). It can be seen that the geofoam is trimmed and placed around the cylindrical piles after pile driving so a small void is left between the pile and geofoam. This also illustrates the inclusion of a geomembrane and concrete load distribution slab over the geofoam. Figure 10.7 presents a typical design detail for a geofoam supported bridge abutment from the bridge rehabilitation project over the Shoshone River near Yellowstone Park in Wyoming. This detail was prepared by the Wyoming Department of Transportation (7) and is discussed in more detail in Chapter 11. Detail A in Figure 10.7 illustrates the joint system between the approach slab and bridge abutment. Figure 10.8 illustrates the design of the bridge approach pavement system for the Shoshone River project. Cross-section C-C illustrates the pavement system at the bridge/abutment interface, which consists of a concrete pavement at the bridge/abutment interface. Cross-section B-B illustrates the pavement system at a distance of approximately 610 mm (24 in.) behind the abutment, which includes an asphalt overlay on the concrete pavement. Figure 10.8 also includes a cross-section of the geofoam embankment parallel to the abutment whereas Figure 10.7 presents a cross-section of the embankment perpendicular to the abutment. Figure 10. 6. Detail for geofoam embankment with a pile-supported bridge abutment (6). Figure 10.7. Detail for geofoam backfill behind a bridge abutment (7). Figure 10.8. Detail of bridge approach pavement system over geofoam (8). UTILITY AND ROADWAY HARDWARE DETAILS A major consideration in roadway embankments is the inclusion of utilities in a geofoam embankment and the installation of roadway hardware, such as guardrails, on top of a geofoam

10-5 embankment. These features are illustrated using a four-lane state roadway (143rd Street) in Orland Park, Illinois and the drawings were prepared by the Illinois Department of Transportation (9-11). Figure 10.9 presents a cross-section through the Orland Park geofoam embankment, which illustrates the location of a storm drain and a guardrail system on the right side of the roadway. The storm drain is located near the centerline of the roadway and consists of a discontinuity in the geofoam for placement of the pipe and trench backfill. Figure 10.10 presents a detail of the drainage pipe installation and it can be seen that the pipe is underlain by one EPS- block. This block was inserted into the native soil to counter balance or offset the weight of the trench backfill material placed around the drainage pipe to reduce differential settlement of the embankment. After placement of the pipe above the EPS block, the discontinuity in the geofoam was backfilled with a granular material. Figure 10.11 presents a detail for the installation of the guardrail system on top of the Orland Park geofoam embankment. It can be seen that the guardrail post is inserted into a concrete foundation that was constructed above the geofoam to provide the necessary impact resistance. Figure 10.12 presents a photograph that depicts the placement of geofoam around a manhole in a different Orland Park geofoam project (131st Street). The EPS blocks where cut in the field to fit around the manhole pipe and some of the trimmings of EPS are visible near the manhole. Finally, Figure 10.13 illustrates the use of geofoam to support a sidewalk that was undergoing large settlement due to subsidence of a peat layer underlying the soil embankment and displacement of the peat into the lake on the right hand side of the photograph. The sidewalk is adjacent to Washington State Route 516 and the case history is referred to as the Lake Meridian settlement repair in Chapter 11. Figure 10.9. Cross-section through geofoam embankment containing a storm drain and guardrail (9). Figure 10.10. Detail of storm drain pipe in geofoam embankment (10). Figure 10.11. Detail for guardrail on top of geofoam embankment (11). Figure 10.12. Photograph of geofoam placement around a manhole.

10-6 Figure 10.13. Photograph of geofoam used to support a sidewalk on top of an earthen embankment (Washington State Dept. of Transportation). DESIGN DETAILS FOR PROTECTIVE LOAD DISTRIBUTION SLAB The uncertainties that are usually associated with inclusion of a load distribution slab warrant a separate section for this topic even though it is mentioned above. Figure 10.4 presents a detail for the construction of a concrete load distribution slab over and EPS embankment for the Interstate 15 project near Salt Lake City (4). It can be seen that the load distribution slab consists of No. 19 steel reinforcing bars at a spacing of 254 mm (10 in.) and the slab is placed directly over the EPS blocks. A load distribution slab is only required if Step 14 (load bearing analysis) and Step 15 (pavement system design) of the EPS-block geofoam design procedure shown in Figure 3.3 indicates that a slab is required to distribute vehicle stresses to suitable levels or to reduce the thickness and cost of the pavement. As indicated in Chapter 4, a load distribution slab represents a significant cost on a project and can range from 20 to 30 percent of the total project cost. Additional concerns with a load distribution slab include the potential for sliding of the slab during an earthquake, potential for ponding of water within the pavement system, and the increased potential for differential icing and solar heating. However, a load distribution slab will typically be required to support heavy traffic loads or high-volume traffic such as encountered on interstate highways. A slab is also typically required when a vertical embankment is used to support the upper part of the exterior facing system and to provide anchorage for various highway hardware such as safety barriers, signage, and lighting. Alternate separation layers that can be considered include a geogrid, geocell with soil or PCC fill, and soil cement. ANCHORING DETAILS FOR HYDROSTATIC UPLIFT Figure 10.14 presents a cross-section for a pile-supported pavement in Japan that utilized an anchoring system to prevent hydrostatic uplift of the EPS-block geofoam (12). An anchoring system was required because the overburden applied to the EPS was insufficient to prevent uplift

10-7 of the blocks if they were subjected to the design water level acting on a side of the embankment. Also shown in Figure 10.14 is a detail of the anchor extending through the load distribution slab overlying the geofoam. Figure 10.14. Anchoring system used to prevent hydrostatic uplift (flotation) of EPS-block geofoam (12). INSTALLATION OF EPS-BLOCK GEOFOAM Figure 10.15 presents an overview of installation of EPS-block geofoam for the 131st Street project in Orland Park, Illinois. The project involves a residential street and the geofoam was used to construct a roadway embankment over a soft clay deposit. Figure 10.16 presents a close-up photograph of the geofoam placement. This photograph illustrates the use of metal connectors between the EPS blocks and the close contact of the individual blocks after placement. Figure 10.15. Photograph of geofoam placement for a residential street. Figure 10.16. Photograph of metal connectors between geofoam blocks. REFERENCES 1. Zaheer, M. A., “Experimental Feature Study The Use of Expanded Polystyrene (EPS) in Pavement Rehabilitation S.R. 109 in Noble County, Indiana.” Indiana Department of Transportation Materials and Tests Division, Indianapolis (1999) 17 pp. 2. Mimura, C. S., and Kimura, S. A., “A Lightweight Solution.” Geosynthetics '95 Conference (1995: Nashville, Tenn.) Conference Proceedings, Nashville, Tenn., Vol. I (1995) pp. 39-51. 3. “Typical Section Geofoam (EPS) Wall.” I-15 Corridor Reconstruction, Elev.-Geofoam Wall (8 m - 11 m), Corridor Standard Plan, Utah Dept. of Transportation (1998) pp. CS- 77. 4. “Load Distribution Slab Restraint Section.” I-15 Corridor Reconstruction, Elev.- Geofoam Wall (8 m - 11 m), Corridor Standard Plan, Utah Dept. of Transportation (1998) pp. CS-80. 5. “Precast Wall Panel.” I-15 Corridor Reconstruction, Elev.-Geofoam Wall (8 m - 11 m), Corridor Standard Plan, Utah Dept. of Transportation (1998) pp. CS-44. 6. “Typical Geofoam Section at Bridge Abutments.” I-15 Corridor Reconstruction, Elev.- Geofoam Wall (8 m - 11 m), Corridor Standard Plan, Utah Dept. of Transportation (1998) pp. CS-50. 7. “Section A-A (Abut No. 1).” Approach Slab No. 1 Details, Bridge Rehabilitation Bridge Over N.F. Shoshone River US 14,16,20 (P-31), KP 51.50 (MP 32.01), Wyoming Dept. of Transportation (1997) pp. Sheet 9. 8. “Section B-B, C-C, D-D.” Approach Slab No. 1 Details, Bridge Rehabilitation Bridge Over N.F. Shoshone River US 14,16,20 (P-31), KP 51.50 (MP 32.01), Wyoming Dept. of Transportation (1997) pp. Sheet 10.

10-8 9. “Sta. 77+00 to 81+00.” 143rd Street Expanded Polystyrene Foam Typical Sections and Details, Illinois Dept. of Transportation (1998) pp. Sheet 25B. 10. “EPS Layout Beneath Storm Sewer.” 143rd Street Expanded Polystyrene Foam Typical Sections and Details, Illinois Dept. of Transportation (1998) pp. Sheet 25D. 11. “SPB Guardrail Type A. Special.” 143rd Street Expanded Polystyrene Foam Typical Sections and Details, Illinois Dept. of Transportation (1998) pp. Sheet 25D. 12. Ninomiya, K., and Ikeda, M., “Design & construction of EPS method which surfacing and uses anchor for prevention.” International Symposium on EPS Construction Method (EPS Tokyo '96), Tokyo, (1996) pp. 162-167.

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