ROCK SQUEEZE STUDY OF TWO DEEP EXCAVATIONS AT NIAGARA FALLS.

Abstract

This paper postulates a concept of long-term recovery of strain energy from sedimentary rocks, and relates it to the phenomenon of ″rock squeeze″ commonly found in structures built in rock. A finite element modelling of rock squeeze based on this concept of post-excavation energy release is described. The model permits a quantitative evaluation of the progressive movements around an underground excavation, the long-term relief of stresses in the rock mass adjacent to the excavation, and the rock-structure-time interaction of a structurally supported system. The use of this model is exemplified by an analytical study of the Canadian Niagara wheelpit which has a rock-squeeze history of 70 years. The results of the analysis are discussed in terms of the many observations and measurements made on the wheelpit and on similar excavations subjected to the adverse effect of rock squeeze.