Harry Nice Bridge Geotechnical Instrumentation Case Study-PPT Presentation

PPT Presentation

Pdf Summary

The case study describes geotechnical instrumentation for construction of a new four-lane bridge beside the 80-year-old Governor Harry W. Nice Memorial Bridge over the Potomac River. The existing bridge, built between 1938 and 1940, is a two-lane structure with 27 piers and 59 approach bents. The new bridge was built less than 150 feet away, with embankment fills up to 30 feet high and 36-inch-square prestressed concrete piles.<br /><br />Subsurface conditions included existing fill, alluvial river deposits, terrace soils, and several underlying geologic formations. Design considerations included pile capacities of 500–1,000 kips and estimated embankment settlements of 3–8 inches.<br /><br />Monitoring was intended to track potential effects on the existing bridge and surrounding ground during construction. The instrumentation program included 122 survey prisms, 20 tilt sensors, 10 vibration monitors, eight strain gauges, 16 settlement plates, 14 piezometers, seven inclinometers, and two crack gauges. Baseline monitoring preceded construction monitoring. Thresholds were set at 1.0 inch per second for vibration, 0.5 inch for settlement or heave, and 0.08 degrees for angular distortion.<br /><br />Project challenges included access limitations, environmental and archaeological constraints, COVID-related restrictions, and proximity to a military facility. The presentation also examined the effects of pile driving at the Virginia abutment and for fender piles. It outlines the monitoring approach and project conditions but does not provide a clear summary of measured impacts or final monitoring results.

Keywords

geotechnical instrumentation

bridge construction

Potomac River

monitoring program

pile driving

settlement monitoring

vibration monitoring

tilt sensors

piezometers

prestressed concrete piles