Creating Queen’s Marque Part II: Inclined Rock Anchors

Aerial view of Queen's Marque

The steel sheet pile (SSP) cofferdam has been designed to resist external soil and hydrostatic pressure. This was accomplished by installing a series of internal structural steel walers and 63 rock anchors that are inclined at 45 degrees down towards the underlying bedrock. Additionally, 162 king pin piles were also installed on the north, west and south sides of the SSP cofferdam. These piles will comprise pipe piles socketed into the bedrock to provide additional resistance from external soil and hydrostatic pressure.

The inclined rock anchors are installed at the SSP waler, which is a heavy structural steel beam located on the inside of the cofferdam and which is installed at approximately elevation + 4.0 feet (or approximately four feet below existing grade). From the cofferdam waler elevation, the post-tensioned rock anchor is installed at a 45 degree angle down to bedrock. The inclined rock anchors were installed generally as follows: