UC BERKELEY SOIL-NAIL WALL MONITORING

LOCATION

Berkeley, California

MARKET

Development

OVERVIEW

The Stanley Biosciences and Bioengineering Facility is the largest research building on the campus of University of California Berkeley, with three basement levels and eight above-ground levels. Construction required an excavation up to 83 feet deep through clayey shale, greywacke, and a groundwater table about 10 feet below ground. The Hayward fault runs about 600 feet away. MACTEC, the geotechnical engineer, designed a soil-nail wall earth-retention system to accomplish the excavation. They needed to monitor forces in the soil nails during construction.

SOLUTION

Geodaq installed 48 GST modules at different locations along the length of eight soil nails, connecting a total of 96 strain gauges. During construction, strain gauge readings were acquired from the embedded GST modules using a single

cable. A traditional approach would have required connecting over 380 instrumentation wires to a data logging system, but Geodaq's sensor network eliminated potential sensor to logger errors and greatly simplified field installation, thus reducing costs.

GEODAQ DELIVERED

• 96 strain gauges and 48 GST modules, installed on eight soil nails using one cable.
• 100 percent of strain gauges survived installation and were functioning after soil-nail bar insertion and grouting.
• Monitoring station with GCM controller module and wireless internet modem in protective casing, installed at the top of the soil nail wall.
• Dedicated server, secure database, and redundant backup for data storage of a total of 213,258 readings, without a single missed reading.
• Frequent sampling for clear indication of strain changes at the initiation of each lift excavation.
• Password-protected web interface for real-time data monitoring and analysis.