This paper describes a new iterative technique for the solution of linear systems of equations arising in petroleum reservoir simulation. The procedure exploits a powerful, vectorizable preconditioner to accelerate generalized conjugate residual methods. Speed and robustness of the new method compare favorably with previously published schemes. These attributes will be demonstrated in actual applications.
Duncan Dam is a B.C. Hydro facility constructed on the Duncan River in southeastern British Columbia, Canada, between 1965 and 1967. The dam was founded on a complex sequence of more than 380 m of glacial drift and glaciofluvial sediments, some of which are pervious and compressible. Some sandy units are potentially liquefiable, in particular a sand layer (unit 3c) up to 23 m thick. Current B.C. Hydro seismic guidelines for dams require that Duncan Dam should be able to withstand the Maximum Credible Earthquake (MCE) without catastrophic release of the reservoir. This paper describes the geologic and seismic setting of the region around the dam and the selection of seismic ground motion parameters. Probabilistic methods were applied to develop MCE ground motions, which were estimated to consist of a firm ground peak horizontal acceleration of 0.12 g , which could be caused by a M 6.5 earthquake at a distance of about 50 km. Several time histories with characteristics similar to this design earthquake were selected for dynamic soil analyses. K~) J ~vorrls: dam safety, embankment dam, liquefaction, sand, seismicity, seismic ground motion. Le barrage Duncan est un ouvrage de B.C. Hydro construit sur la rivibre Duncan dans le sud-est de la ColombieBritannique au Canada entre 1965 et 1967. Le barrage repose sur une succession complexe de plus de 380 m de sCdiments dktritiques et fluvio-glaciaires dont certains sont permkables et compressibles. Quelques unitks sableuses peuvent prCsenter un danger de IiquCfaction, en particulier une couche de sable (unit6 3c) ayant:-jusqu'ii 23 m d'Cpaisseur. Les rbgles sismiques en vigueur actuellement i B.C. Hydro pour les barrages exigent que le barrage Duncan soit capable de rCsister au sCisme maximum envisageable (<< MCE D) sans dkversement catastrdphique du rCservoir. Cet article dCcrit les conditions gCologiques et sismiques dans la rCgion entourant le barrake et le choix des paramgtres pour les mouvements sismiques du sol. Des mCthodes probabilistes ont Ct C appliquCes pour reconstituer les mouvements du terrain correspondant au MCE. On a estimC que l'on pourrait avoir un picdd'accCICration horizontale du terrain de 0,12 g, provenant d'un tremblement de terse d'amplitude M 6,s 4 une-distance d'environ 50 km.Pour les analyses dynamiques des sols, on a choisi plusieurs cas historiques tirCs du pass6 et presentant des caractkristiques semblables ii celles du sCisme prCvisionnel.Mots cle's : sCcuritC des barrages, barrage digue, IiquCfaction, sable, sismicitC, mouvement sismique du sol.[Traduit par la rCdaction]Can. Geotcch. J. 31, 919-926 (1994)
Strong motion monitoring in Canada has undergone significant changes in recent years. Most analogue, non-communicating instruments have been replaced with modern digital instruments that provide information in real-time. Dense networks are being deployed in the urban centres of southwest British Columbia to provide shaking parameters and "shake maps" immediately after an earthquake. Monitoring of critical infrastructure, including bridges, dam sites and transmission facilities is increasing. This article documents the current state of strong motion monitoring across Canada, and summarises the data sets that are currently available. As of 2007, the Geological Survey of Canada operates 97 strong motion instruments (all Internet Acclerometers or IA's) in western Canada, most of which are deployed in the urban centres of high seismic hazard in southwest British Columbia. BC Hydro has 39 strong motion instruments at dam sites across BC. More than half of these are analogue SMA-1's, and are scheduled to be replaced by digital instruments within 2-3 years. BC Transmission Corporation owns 23 instruments (SSA-2's and ETNA's) installed at major substations and terminal stations across southwest BC. Other strong motion instruments in western Canada are owned by utilities or transportation organisations (BC Ministry of Transportation (MoT) has deployed 17 instruments to monitor lifeline bridges and a tunnel). In eastern Canada, the GSC operates a network of 26 strong motion instruments in the active Charlevoix zone, and 11 instruments in greater Ottawa. Hydro-Québec operates instruments at 12 dams and substations. Gaz Metropolitain operates an instrument at its Montreal LNG plant and New Brunswick Power operates an instrument at the Point Lepreau nuclear station. During the past six years, nearly 700 accelerograms have been recorded across Canada. Most of the records represent weak motion (PGA less than 5%g), nonetheless, they are useful for evaluating local site response, which in turn may be valuable to engineers evaluating strong ground shaking during future earthquakes.
The hydraulic structures of the proposed site C hydroelectric project in northeastern British Columbia would require deep excavations in Lower Cretaceous Shaftesbury shales. A significant stress relief would occur over most of the area to be occupied by the structures. Concerns about the magnitude and rate of time-dependent rebound and their impacts on project design, construction, and operation have been addressed. A review was made of several important case histories of other major projects constructed on Prairie shales. The properties of those shales were compared with the Shaftesbury shales. Long-term testing to establish the shale swelling characteristics was performed. Analyses were then made to evaluate potential elastic and time-dependent rebounds of the project area. A procedure for computing stress changes and time-dependent deformations due to the unloading effect of excavation followed by structural loading was developed. The procedure is useful in determining differential rebound that would occur in areas of steep topography or significant variations in the distribution of structural loads. Key words : rebound, shales, dam, swelling properties, swelling pressure, stress relief, deep excavations.
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