Rotifers in Ecotoxicology

Abstract

A comprehensive project has been completed at the University of British Columbia that focused on the development ,of a commercially competitive composite cable bolt. Laboratory evaluation consisted of pull tests, preliminary shear tests, grout column testing and scanning electron microscope evaluation of the composite cable bolt. Field implementation at five underground mines throughout Canada were completed for technical and overall performance evaluation of the new product. (from Authors) 955248 A constitutive law for bond failure of fully-grouted cable bolts using a modified boek cell A. A series of pull tests were performed using fully-grouted seven-wire strand cable, in which the confining pressure at the outside of the cement annulus was maintained constant using a modified Hoek cell. The bond strength was shown to increase with confining pressure. The associated radial displacements at the outside of the cement annulus were measured and decreased with confining pressure. The data were used to develop a frictional-dilational model for cable bolt failure in both graphical and mathematical form. The latter is amenable to implementation in numerical programs, and presents an opportunity to incorporate realistic cable bolt behaviour into numerical analyses. The miniscule radial dilations induced by bond failure, which are responsible for the generation of radial pressure at the cable-grout interface and the development of frictional bond strength, explain the sensitivity of the bond strength to: 1) the grout quality, 2) the radial stiffness of the borehole wall and 3) mining-induced destressing. (Authors) Shotcrete 955249 Sbotcrete support design in blocky ground: towards a deterministic approach