Jet Grouting for the Ruskin Dam Right Abutment Upgrade

NM Sweeney

In the proceedings of: GeoVancouver 2016: 69th Canadian Geotechnical Conference

Session: INFRASTRUCTURE - VII Embankment Dams

ABSTRACT: Jet grouting was carried out as part of the upgrade for the right abutment of Ruskin Dam, which consisted of a new plastic concrete seepage cut-off wall. Two types of jet grouting were used at the tie-in of the new cut-off wall with the concrete dam: single fluid jet grouting was used to strengthen the Quadra Sand deposits beneath and adjacent to the sloping west end of the concrete dam which had been constructed against overburden on the abutment, and double fluid jet grouting was used to treat soils downstream of the dam and buttress the tie-in. The single fluid columns were up to 25 m deep and sealed to bedrock, and provided homogeneous soilcrete beneath and adjacent to the concrete dam for the subsequent construction of a continuous slot to connect the cut-off wall into the concrete dam with a flexible asphalt mastic material. Prior to jet grouting at the dam, extensive field trials were carried out to determine the expected diameter of both types of jet grout columns, to calibrate the response of nearby piezometers, and to ensure that jet grouting could be carried out safely, without compromising the safety of the dam. Dam safety risk mitigation included the construction of a barrier wall, limiting the use of air during jet grouting, and closely monitoring the piezometric levels in the abutment. Pre-drilling was carried out to ensure that the jet grout columns were sealed to bedrock. Due to the loss of reflow in a localized coarse zone near the bottom of the loose fill that was placed during the original construction, additional work was required to pre-treat the fill with a cement-bentonite grout prior to jet grouting.

RÉSUMÉ: latéral droit du barrage Ruskin. Ces travaux consistaient à réaliser une nouvelle paroi étanche en béton plastique. Deux on de coulis à ouest inclinée du barrage en béton construite contre les morts-jet de fluide, pour traiter les sols en aval du barrage et étayer le raccordement. Les colonnes mises en place par jet -béton (Soilcrete) homogène en dessous et s sur le terrain afin de déterminer le diamètre prévu des -trous a percolonnes coulis au substratum rocheux. En raison de la perte de reflux dans une zone localisée de matériau grossier située près du fond du remblai lâche mis en place au cours de la construction initiale, des travaux supplémentaires ont -

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