Bridge Foundation Design, I-95 Atlee-Elmont Interchange
Location
Hanover County, Virginia
Client
Wilbur-Smith Associates
Services Provided
Subsurface Exploration
Soil Laboratory Testing
Foundation Design Recommendations
Earth Pressure Analysis
Seismic Analysis
Project Overview
Schnabel provided geotechnical engineering services for the foundation design of 11 bridges at the I-95 Atlee-Elmont Interchange. The bridges for this project include three to five spans with bridge lengths of 120 to 650 feet, and cross two streams, the existing interstate highway, and large expanses of marshland. Our services on this project included the design, coordination and observation of both preliminary and final subsurface explorations. The explorations included drilling 105 test borings, many of which involved difficult access conditions. In the upland portions of the site, subsurface conditions consist of Terrace deposits over the Miocene Age Calvert Formation over Petersburg Granite bedrock. In the lowland portions of the site, some of the Terrace and the Calvert Formation deposits have been eroded and partially replaced with Recent alluvial deposits. Schnabel undertook a comprehensive laboratory test program to develop parameters for use in foundation design.
Using the data developed in the subsurface exploration and laboratory testing programs, Schnabel provided foundation recommendations for the proposed bridges. We considered a variety of foundation options, including spread footings, belled drilled shafts on soils, drilled shafts on rock, and driven pile foundations. We also provided earth pressure recommendations for abutment structures, and retaining structures associated with the construction. Our design analysis included seismic analysis of the Seismic Performance Category B structures.