9612136 Accurate prediction of ground movements due to tunnels and deep excavations is not only an important part in the design of lateral earth retention systems, but is also essential for estimating the risk of damage to surrounding facilities. Deformation prediction is an integral part of the design-construction process, and provides a framework for interpretation of instrumentation measurements during construction and for extrapolating limited measurements made at early construction stages to assess the impact of construction activities. This research project is directed toward improving the quality of numerical predictions of ground movements and structural requirements associated with deep excavations and tunneling in soils, and to further develop the use of numerical analysis as a design tool. A new advanced effective stress constitutive model will be implemented which unifies the modeling of clays, sands and silts into a finite element code able to perform coupled flow and soil deformation analysis. A fundamental but "realistic" evaluation of major factors controlling the performance of deep excavations and tunnel will be completed. The capabilities of the model will be validated through comparison with performance using a well documented study of a tunnel and cut-and-cover section in San Francisco Bay mud, a process which will include a) extensive field instrumentation, b) complete characterization of the soil profile, and c) a well documented history of the construction sequence and relevant events which occur during the project. ***
