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Earthquake Induced Rock Shear Through a Deposition Hole. Effect on the Canister and Buffer

Published online by Cambridge University Press:  01 February 2011

L. Börgesson ,
L.-E. Johannesson  and
J. Hernelind
L. Börgesson
Affiliation:
Clay Technology AB, Ideon Research Centre, SE-223 70 Lund, Sweden
L.-E. Johannesson
Affiliation:
Clay Technology AB, Ideon Research Centre, SE-223 70 Lund, Sweden
J. Hernelind
Affiliation:
FEM-Tech AB, Pilgatan 8, SE-721 30 Västerås, Sweden
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Abstract

Existing fractures crossing a deposition hole may be activated and sheared by an earthquake. The effect of such a rock shear has been investigated in a project that includes both laboratory tests and finite element calculations.

A number of laboratory tests have been performed with shearing of water-saturated bentonite samples at different densities and shear rates. From those tests a material model of the buffer that takes into account the shear rate has been formulated. Shear rates up to 6 m/s have been tested.

The rock shear has been modelled with finite element calculations with the code ABAQUS. A 3D finite element mesh of the buffer and the canister has been created and a number of calculations with simulation of a rock shear have been performed. The rock shear has been assumed to take place perpendicular to the canister axis in either the centre of the deposition hole or at the ¼ point. The shear calculations have been driven to a total shear of 20 cm. Buffer densities at water saturation between 1950 and 2100 kg/m3 and shear rates between 0.0001 and 1000 mm/s have been modelled. The influence of buffer density, shear plane location, the shear rate and the magnitude of the shear displacement are analysed and discussed.

The results show that the influence of especially the density of the buffer and the location of the shear plane are very strong but also that the shear rate and the magnitude of the shear displacement have a significant effect.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 807: Symposium Scientific Basis for Nuclear Waste Management XXVII , 2003 , 521
Copyright
Copyright © Materials Research Society 2004

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References

REFERENCES

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