Project Location: 350 Rhode Island Street, San Francisco, California
Client: Dames & Moore; San Francisco, California
Dates: January-2000 to March-2000

The foundation for a multi-story building project was preliminarily designed with drilled shafts of large diameters supporting single-column loads. The site for the project was composed of soft layers of clayey soil underlained by layers of serpentine rock with various degrees of weathering. The serpentine rock is hard to categorize in mechanical properties due to the difficulty of sampling and testing. Rock samples indicated severely weathered and sheared serpentine in many locations and depths. The geotechnical designers believed necessary to perform a fully instrumented axial load test in order to determine the soil transfers that may be obtained in the serpentine rock.

LCR&A was contracted to perform the load test, design, and install internal and external instrumentation, reduce test data, and to help during the process of data interpretation. Modern instruments, known as "strain bars" were designed, manufactured, and installed for the measurement of total stresses at different depths of the test shaft. An automated data acquisition system continuously monitored the progress of the load test and digital data was evaluated at every step of the test. The information gathered from the load test proved to be very valuable for the geotechnical engineers and for the owner.