NSF Award
9207865
The objective of this study is to further verify the feasibility of applying breakout geometry to underground excavation in real rocks. a large scale polyaxial testing machine will be used in order to eliminate all boundary effects on the measured excavation response . A Finite Element code, capable of elasto- plastic analysis, will be used in order to numerically model the breakout phenomenon and determine the strength of various excavation geometries. The numerical model will also be used for generation of database which would contain the most stable excavation geometries under different stress conditions and for various rock types. These data will provide guidelines in real practice for modification or design of Tunnel Boring Machines (TBM).
