Author(s): M. A. Rist; S. A. F. Murrell; P. R. Sammonds
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Abstract: The relationship between ice strength and failure mechanism has been investigated experimentally at -20°C under various conditions of constant deformation rate and confining pressure. The work was carried out using a low temperature triaxial testing cell recently installed at University College, London. In this apparatus a hydrostatic pressure is maintained around a jacketed cylindrical sample while an axial load is applied using a servo-controlled actuator. Test samples consisted of low porosity laboratory-made polycrystalline ice of controlled grain size and random crystal orientation. Tests were conducted at high strain rates (between 10-2 s-1 and 10 -4 s-1) and moderate confining pressures (up to 30MPa) in order to promote crack growth and macroscopic fracture. Results at 10-2 s-1 indicate a change in failure mechanism from crack propagation to creep with associated cracking as confining pressure is increased. Behaviour at lower strain rates is predominantly ductile but failure strength may still be affected by cracks where their formation is not sufficiently inhibited by confining pressure.
Year: 1988