ABSTRACT
T. Gregor & B. Garrod Hatch Mott MacDonald, Mississauga, Ontario, Canada
D. Young Hatch Mott MacDonald, Pleasanton, California, USA
ABSTRACT: The City of Coronado, California, has initiated the design for the State Route 75/282 Transportation Corridor Project. This project includes the design of approximately 5700 feet (1740 m) long twin road tunnels. The shallow, 32′–6′′(9.9 m) finished diameter, tunnels will be crossing the seismically active Coronado Fault. A cut-and-cover box structure or twin bored tunnels lined with precast segmental concrete linings, have been considered as options in the area of the fault crossing. Assessment of the structural behaviour of these options during fault rupture consisted of the development of finite difference (bored tunnels) and finite element (cut-and-cover boxes) analytical models. Both types of models reflected non-linear stress-strain ground behaviour. The results of the design analyses have shown that it is possible to assess the structural behaviour of underground structures under severe ground displacement conditions using numerical analysis and to develop structural solutions.
