Stress relief and cliff stability at a power station near niagara falls

Abstract

The effects of long-term stress relief in a cliff behind a hydroelectric power station at Niagara Falls are examined both factually and analytically. A consideration of the history of crestline recession of the Horseshoe Falls indicates that the age of this cliff is probably in the order of 400 years. Over this period of time, gradual release of strain energy from the rock mass resulted in a progressive movement of the cliff towards the Niagara Gorge, accompanied by the development of vertical jointing behind the face of the cliff. This and other findings of the analytical study are apparently in agreement with the general observations made along the Niagara Gorge, as well as with the results of in-situ stress measurements obtained in the area. It is further suggested that the combination of vertical jointing and horizontal bedding contributes to the disintegration of the rock mass in and above the Rochester Shale Formation, enhancing the occurrence of rockfalls and the erosion of the Niagara Gorge itself. © 1978.