Coupled Hydro-Mechanical Behaviour of In-Situ Shaft Sealing Components

Abstract

Decommissioning and closure of Canada’s Underground Research Laboratory (URL) involved the installation of a full-scale 5-m diameter by 12-m long shaft seal. This installation spans a major water-bearing fracture zone located at a depth of 275 m and is intended to isolate two hydrogechemcial regimes. Coupled hydro-mechanical (H-M) numerical modelling was conducted using the finite element method to examine the performance of this shaft seal and the numerical results were compared with the measured values. Overall predictions of changes in degree of saturation in the clay seal component show good agreements with the measured data. Both numerical results and measured data indicate gradual increase in the total pressure in the clay seal due to swelling of clay during hydration. Performance of coupled H-M analyses has provided a better understanding of various inter-related phenomena occurring during hydration of the shaft seal components.