The Determination of the Rock Properties That Are Measured by Cylindrical Pressure Cell Tests in Boreholes.
Miller-RJ; Duvall-WI; Wang-FD
NTIS: PB/266-829 Available for Reference At Bureau Libraries :47 pages
This research investigates the validity of the assumption of complete pressure transfer through the adiprene sleeve of the cylindrical pressure cell at the Colorado School of Mines and referred to as the csm cell, and what effect rock properties have on the determination of deformation modulus by the cell. Also, an extension to the grant was obtained to investigate the feasibility of using inclusion gages in the adiprene sleeve to measure borehole dilatation directly. A rigorous theoretical analysis of a soft inclusion restrained in the axial direction inside a thick-walled cylinder indicated that all the pressure should be transmitted across the sleeve provided poisson's ratio approaches 0.5. Tests in metal and rock thick-walled cylinders confirmed that the pressure transfer is essentially complete, independent of the relative stiffness of the cylinder. Several configurations of inclusion gages were tested. A number of difficulties were encountered in mounting strain gages in adiprene, but a successful technique for molding the gages in the sleeve was developed. Suggestions are made for solving the problem of too high strain observed in the inclusion gages, and it appears a cylindrical pressure cell with inclusion gages would offer a faster, more accurate means of obtaining deformation modulus in situ at a relatively low cost. Test results in rock thick-walled cylinders agreed well with expected behavior and the cylindrical pressure cell appears to be a valuable tool for in situ material evaluation.
CP; Final Contract Report;
NTIS Accession No.
NTIS: PB/266-829 Available for Reference At Bureau Libraries
Colorado School of Mines