FY2002 Final Report for EMSP Project No.70108 Effects of Fluid Distribution on Measured Geophysical Properties for Partially Saturated, Shallow Subsurface Conditions
FY2002 Final Report for EMSP Project No.70108 Effects of Fluid Distribution on Measured Geophysical Properties for Partially Saturated, Shallow Subsurface Conditions Our goal is to improve geophysical imaging of the vadose zone. We are achieving this goal by providing new methods to improve interpretation of field data. The purpose of this EMSP project is to develop relationships between laboratory measured geophysical properties and porosity, saturation, and fluid distribution, for partially saturated soils. Algorithms for relationships between soil composition, saturation, and geophysical measurements will provide new methods to interpret geophysical field data collected in the vadose zone at sites such as Hanford, WA. This report summarizes work after 32 months of a 3-year project. We modified a laboratory ultrasonics apparatus developed in a previous EMSP project (No.55411) so that we can make velocity measurements for partially-saturated samples rather than fully-saturated or dry samples. Modifications included adding tensiometers and changing the fluid system so that pore fluid pressure can be controlled and capillary pressure can be determined. We made a series of measurements to determine properties of partially saturated Ottawa sand and Santa Cruz aggregate samples as well as sand-clay samples and some preliminary measurements on natural soils. Current measurements include investigations of effects of pore fluid chemistry on grain cementation and velocities for calcite-cemented sand samples. We analyzed these measurements as well more »
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