Deep Dive: Using Physical Models to Design Hydraulic Structures for Deep Tunnels

Tunneling projects to convey sewage or mitigate combined sewer overflows (CSOs) are being designed and built around the world. In many situations, urban site constraints do not allow the construction of traditional hydraulic structures such as interception chambers, drop shafts, vents, and deaeration chambers, which are typically used to convey near-surface flows to deep tunnels. Numerical and physical modeling can be important tools in developing, testing, and optimizing the design of these structures. Physical modeling, the focus of this paper, plays a critical role in assessing air management, sedimentation issues, debris handling, and complex two-phase flow phenomenon that cannot be adequately assessed using current numerical capabilities. For decades, IIHR – Hydroscience & Engineering at the University of Iowa has played a critical role in performing physical model studies to address just such issues. This paper provides an overview of several physical modeling projects, and provides specific examples of design issues investigated and optimized using the unique capabilities of physical models.