SIZE EFFECT IN MODELING THE ROCK MASS RESPONSE TO THEEXCAVATION OF A TUNNEL

摘要

The process of spalling failure around a deep excavation in rock masses is one of the main problems in tunnel construction.Itrnconsists in a brittle failure, produced by crushing of compressed rock, after the onset of strain localization.To betterrnunderstand the reasons for this failure, and mainly to prevent it, a plane strain model is here proposed to evaluate the effectsrndue to the reduction of confinement during the excavation.The effectiveness of the model is proved by comparing theoreticalrnresults with test data, and its capability to predicting size effects is also tested.