سال انتشار: ۱۳۹۰

محل انتشار: اولین کنفرانس بین المللی و سومین کنفرانس ملی سد و نیروگاههای برق آبی

تعداد صفحات: ۱۰

نویسنده(ها):

S BALIAN – Divisional Director
M SCHOEPF – Senior Consulting Engineer

چکیده:

The construction of an exceptionally deep cut-off wall under the main dam body of the Peribonka Dam in Canada, to create a waterproof barrier in highly permeableriverbed alluvia, was completed end of October 2006. The cut-off wall, made of plastic concrete, was exceptional by its depth, of almost 116 m, and by the extremely complexgeotechnical surrounding. The cut-off wall was constructed with the Bauer hydraulic trench cutter system. The preliminary geotechnical investigation boreholes hadrevealed that at the dam location the bedrock plunged to very big depths, forming adeep glacial gully. Beside the extreme depth of the bedrock, the design was further complicated by the presence of hard rock including granite, with strength sometimesin excess of 200 MPa, quasi vertical rock cliffs, rock overhangs, and gully’s filling by some coarse alluvia, including boulders. Hydro-Quebec and SNC Lavalin designed a1.50 m wide plastic concrete cut-off wall extending to the full depth of the glacial gully, with limited rock embedment of the wall, leaving open areas along the interfaceto the bedrock, combined with cement grouting in the areas left open. BAUER wasawarded the contract on the basis of an alternative design: the plastic concrete cut-off wall was designed by Bauer to be completely embedded in the bedrock, a designwhich avoided any potentially hazardous area to be sealed by cement grouting. Only a decade ago, the Peribonka dam would not have been deemed feasible due to theextreme complexity of the geotechnical works.