Soil Liquefaction Hazard Assessment by the Vision Cone Penetrometer

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This research program addresses the use of a newly developed Vision Cone Penetrometer (VisCPT) for earthquake-induced liquefaction hazard assessment. The VisCPT is essentially a standard electronic cone penetrometer, modified by inclusion of two miniature CCD video cameras. The cameras collect a continuous stream of video images of the soil stratigraphy by two levels of magnification. The VisCPT can delineate soil stratigraphy, and through various computer vision techniques, provide a grain size analysis of the soil.The objective of this project is to collect VisCPT date at the National Geotechnical Experimentation Site (NGES) on Treasure Island in San Francisco, at locations with variable percentages of fine particles. Physical soil samples are also taken. The collected VisCPT data is evaluated with specific focus on image-texture techniques for determining grain size distributions. The VisCPT images are also compared to standard CPT tip resistance measurements in order to illustrate and quantify the effects of stratigraphic layering and interfaces on CPT readings.