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Title: FY 2000 Annual Report for EMSP Project No.70108 - Effects of Fluid Distribution on Measured Geophysical Properties for Partially Saturated, Shallow Subsurface Conditions

FY 2000 Annual 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 will achieve 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 10 months of a 3-year project. We have 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. We are testing the measurement apparatus using standard laboratory sand samples such as Ottawa sand samples. Preliminary results indicate that we can measure both compressional and shear velocities in these sand samples. We have received Hanford soil samples (sands from split-spoon cores from an uncontaminated site) and expect to make ultrasonic measurements on them also. We have used the LLNL x-ray facility to perform x-ray computed tomography (XCT) imaging for several partially-saturated Ottawa sand and Lincoln sand samples, more » and have also used the DOE Advance Photon Source at Argonne National Laboratory to make higher-resolution images of some sand samples. Preliminary results indicate that we can image amount and distribution of fluids in homogeneous sand samples. Continuing work from the previous EMSP project, we are testing a new data analysis method for seismic data that is expected to improve interpretation of seismic data from the vadose zone by showing how partial saturation affects seismic parameters. Our results suggest that the planned approach for this research is appropriate, that microstructure is an important factor for measured geophysical properties, and that seismic field experiments should be designed to collect both compressional and shear wave velocity data. We are also continuing to develop algorithms for relating geophysical properties to soil composition and hydrological parameters. « less
Authors: ; ; ; ; ; ; ; ;
Publication Date:
OSTI Identifier:792356
Report Number(s):UCRL-ID-137130
TRN: US0300493
DOE Contract Number:W-7405-Eng-48
Resource Type:Technical Report
Data Type:
Resource Relation:Other Information: PBD: 30 Aug 2000
Research Org:Lawrence Livermore National Lab., CA (US)
Sponsoring Org:USDOE Office of Defense Programs (DP) (US)
Country of Publication:United States
Language:English
Subject: 54 ENVIRONMENTAL SCIENCES; 58 GEOSCIENCES; 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; ALGORITHMS; COMPUTERIZED TOMOGRAPHY; DATA ANALYSIS; DISTRIBUTION; MICROSTRUCTURE; PHOTONS; POROSITY; SAND; SATURATION; SHEAR; SOILS; TESTING; ULTRASONIC WAVES; VELOCITY