Projects

Case description

Defective sheet pile walls for a deep excavation project located on the shoreline of Burrard Inlet encountered frequent inrushes of water-bearing soils with development of adjacent sink holes that halted construction of a deep conveyor tunnel. Subsurface site conditions consisted of old dredging spoils from construction of the adjacent Lions Gate Bridge. After site work came to a standstill, our grouting engineer was called to the site to implement grouting operations that would enable site work to resume, as well to provide ongoing engineering support for completion of the remaining excavation work.

Solution

Peter White designed and supervised a $1 million sleeve pipe cement grouting operation to stabilize granular soil conditions beneath and adjacent to the planned deep excavation that enabled excavation work to resume “in the dry”. Supplementary grouting operations were undertaken using water-activated polyurethane resin and various cement grouting additives to tackle occasional inflows that occurred as excavation work proceeded.

Deep portions of the excavation exposed openings in the sheet pile wall, where adjacent sheet piles had split and at some locations where the excavation extended below the bottom of the sheet piles. In these circumstances, the pre-grouted ground conditions were self-supporting and impermeable.

With hands-on engineering support for grouting operations and deployment of various performance-enhancing grouting materials as required, the general contractor was able to complete deep excavation and conveyor tunnel construction as planned.

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