Uses and Limitations of Conventional Hydraulic Models in the Planning and Design of Storage Tunnels

摘要

The hydraulic design of storage tunnels requires special considerations relative to the design of rnconventional sewers. These issues include characterization and control of inflows, energy rndissipation and deaeration at drop shafts, rapid filling, transitions from free-surface to surcharged rnconditions, ventilation of displaced air, deposition of solids and scouring, and odor control. rnConventional hydraulic models can play a significant role toward meeting the planning and rndesign requirements related to many of these issues. For planning and design of CSO control rnprojects in Cleveland, Providence, Fall River, and Portland, conventional models were used to rnsimulate the hydrologic and hydraulic properties of wastewater collection systems and their rnpotential flow contributions to tunneled storage facilities. These CSO programs included a rnvariety of tunnel configurations, on-line and off-line storage, and multiple flow control strategies. rnConventional hydraulic models were used to directly simulate collection system performance for rndesign events, for extended period simulations, and for the evaluation of scouring of deposited rnsolids in the tunnels. Output from these models was also used as input to other more detailed rnevaluations of tunnel system hydraulic characteristics, including: sizing of drop shafts, evaluation rnof rapid filling and the potential for transient pressures, design of emergency overflow structures, rnand ventilation of displaced air. This array of simulations proved to be an important part of the rnoverall design process for these programs.