The Municipal Government of Istanbul plans to construct a second subsea tunnel across the Bosphorus Waterway between the European and Asian sectors of the city. We conducted a 2-D sparker seismic survey in the Bosphorus Waterway to delineate geometry of the sub-bottom unconsolidated sedimentary sequence and geometry of the sediment-bedrock interface, and to determine the locations and depths of the geotechnical boreholes. Based on the interpretation of the seismic image associated with the center line along the planned tunnel traverse, we constructed a geological model that was subsequently used to determine the locations and depths of the geotechnical boreholes. Formation tops determined from geotechnical borings confirm the geological cross-section constructed from the seismic image in depth along the tunnel traverse, except within a segment on the European side where the strong currents of the Bosphorus have severely distorted the 2-D line traverse. This investigation demonstrates the compelling need for a seismic survey prior to geotechnical drilling for accurate description of the soil column both in the lateral and vertical directions within the project area. The seismic survey provided a cost-effective planning of geotechnical drilling to determine the number of boreholes, and where and how deep to drill each borehole. Additionally, the geological model constructed from the seismic image will be used for the tunnel design.
Presentation Date: Tuesday, October 16, 2018
Start Time: 8:30:00 AM
Location: 207A (Anaheim Convention Center)
Presentation Type: Oral
