Instrumentation for Vibro Stone Column Soil Improvement

The Vibro stone column treatment method is widely used for site liquefaction mitigation. Today, the quality control of stone column installation includes the monitoring, recording, and displaying of vibrator penetration depth, energy consumption, gravel consumption, and air pressure to continuously aid the operator and the inspector. In the past 15 years, with the advance of electronic and computer technology, the data acquisition and data recording system for the vibro stone column construction has been developed and widely used in many projects involving the authors. The need for improving the quality of construction led the development of the i-Vibro system, an integrated instrumentation system using TCP/IP based data acquisition technology, wireless communication, graphical user interface, and GPS satellite navigation and gyro technologies for accurate underwater construction. Given the real-time display and comprehensive data, the design geotechnical engineer can better analyze the site response and evaluate the effectiveness of vibro stone column treatment. This paper covers the vibro stone column instrumentation for several projects, including the Mount Hermon and BART (Bay Area Rapid Transit) marine test section projects. The marine project involved the installation of stone columns in over 90 feet of water and only 1.52 meters (5 feet) away from the San Francisco - Oakland trans bay subway tunnel.