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Experimental and theoretical fracture mechanics applied to Antarctic ice fracture and surface crevassing

Rist, MA; Sammonds, PR; Murrell, SAF; Meredith, PG; Doake, CSM; Oerter, H; Matsuki, K; (1999) Experimental and theoretical fracture mechanics applied to Antarctic ice fracture and surface crevassing. J GEOPHYS RES-SOL EA , 104 (B2) 2973 - 2987.

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Abstract

Recent disintegration of ice shelves on the Antarctic Peninsula has highlighted the need for a better understanding of ice shelf fracture processes generally. In this paper we present a fracture criterion, incorporating new experimental fracture data, coupled with an ice shelf flow model to predict the spatial distribution of surface crevassing on the Filchner-Ronne Ice Shelf. We have developed experiments that have enabled us to quantify, for the first time, quasi-stable crack growth in Antarctic ice core specimens using a fracture initiation toughness, K-init, for which crack growth commences. The tests cover a full range of nearsurface densities, rho = 560-871 kg m(-3) (10.9-75.7 m depth). Results indicate an apparently linear dependence of fracture toughness on porosity such that K-int = 0.257 rho-80.7, predicting a zero-porosity toughness of K-o = 155 kPa m(1/2). We have used this data to test the applicability to crevassing of a two-dimensional fracture mechanics criterion for the propagation of a small sharp crack in a biaxial stress field. The growth of an initial flaw into a larger crevasse, which involves a purely tensile crack opening, depends on the size of the flaw, the magnitude of K-init, and the nature of the applied stress field. By incorporating the criterion into a stress map of the Filchner-Ronne Ice Shelf derived from a depth-integrated finite element model of the strain-rate field, we have been able to predict regions of potential crevassing. These agree well with satellite imagery provided an initial flaw size is assumed in the range 5-50 cm.

Type: Article
Title: Experimental and theoretical fracture mechanics applied to Antarctic ice fracture and surface crevassing
Keywords: FRESH-WATER ICE, BOTTOM CREVASSES, TOUGHNESS, SHELF, DISINTEGRATION, RESISTANCE, SPECIMENS, SHEETS, STRAIN
UCL classification: UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Earth Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Inst for Risk and Disaster Reduction
URI: http://discovery.ucl.ac.uk/id/eprint/125317
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