Design and Construction of Large Diameter Piles for Foundation Enhancements at the Site C Dam

January 7, 2026

The Site C hydroelectric project is founded on a shale foundation with prevalent weak bedding planes. A system of 96 shear pile consisting of 2 m diameter 38 mm thick steel pipes filled with concrete was designed to reinforce the right bank foundation and enhance the long-term serviceability and stability of the overlying powerhouse and spillway structures. Laboratory compression tests, borehole pressuremeter tests, and full scale in-situ bi-directional lateral load tests were performed to obtain the stiffness and strength properties of the foundation required for pile design. Stability analyses and 3D deformation analyses in FLAC3D and ABAQUS confirmed that the loads, stresses and displacements satisfy the design criteria. The pile system was successfully constructed, and pile inclinometers have shown negligible displacements since reservoir filling.