Table 2 Summary of key parameters, objectives, and main results obtained from each phase
Phase | Key Inflatable Plug Features | Testing Objectives | Test Scale / Location / Validation | Main Results |
|---|---|---|---|---|
Phase 1: 2007–2008 | • Fitted plug geometry • Low-strength material • Low-pressure air inflation only | • Demonstrate installation and storage outside of the dynamic envelope. • Demonstrate adequate deployment time. • Demonstrate the ability to obtain acceptable tunnel seal. • Establish working relationships with potential end-user organizations. | Reduced scale (1:5.7) Laboratory see-through scale model Inspection and smoke testing | Understanding of deployment dynamics. Several trials with different plug shapes demonstrated the sealing capacity of each shape. |
Full scale Laboratory tunnel mockup Inspection and timing | Installation procedures demonstrated; deployment timing established. | |||
Full scale Transit rail tunnel Inspection, timing, and smoke testing | Installation completed within established time and space requirements; deployment within the required time; indication of ability to achieve an adequate seal. | |||
Phase 2: 2009–2010 | • Fitted plug geometry • High-strength, single-layer material • Full-pressure water inflation against floodwater pressure | • Design and construction of full-scale pressure-capable testing apparatus. • Demonstrate deployment time to full pressure. • Demonstrate the ability to achieve acceptable tunnel seal under pressure. • Identify the advantages and limitations of single-layer plug design. | Reduced scale (1:4) Quarter-scale testing apparatus Inspection and pressurized water testing | Frictional properties adequate to withstand flooding water pressures with an acceptable leakage rate. |
Full-scale surrogate Full-scale tunnel mockup Inspection and timing | Installation procedures demonstrated; deployment timing established. Acceptable deployment; sizing established for final Phase 2 full-scale plug. | |||
Full-scale Vectran fabric Full-scale tunnel mockup Inspection, timing, and pressurized water testing | Frictional properties proved to withstand flooding water pressures, but the strength of single-layer material found to be insufficient to withstand full pressurization. | |||
Phase 2b: 2011–2012 | • High-strength, multi-layer material • Cylindrical plug geometry • Full-pressure water inflation against floodwater pressure | • Demonstrate the ability of the cylindrical plug to conform to tunnel geometry. • Demonstrate the ability to handle a heavier, thicker membrane construction while improving plug deployment and sealing characteristics. • Demonstrate the ability to achieve acceptable tunnel seal under pressure. • Remain stable under water flooding pressure. | Full-scale surrogate Full-scale tunnel mockup Inspection, timing, and smoke testing | Acceptable deployment; sizing established for final Phase 2b large-scale plug. |
Quarter scale Quarter-scale testing apparatus Inspection and pressurized water testing | Frictional properties adequate to withstand flooding water pressures with an acceptable leakage rate and no slippage. | |||
Full scale Full-scale tunnel mockup Inspection, timing, and pressurized water testing | Frictional properties have proven to withstand flooding water pressures with an acceptable leakage rate and sufficient plug strength. | |||
Phase 2b-ET: 2012–2013 | • High-strength, multi-layer material • Cylindrical plug geometry • Full-pressure water inflation against floodwater pressure | • Integrate plug with a modular, soft-pack container for improved installation characteristics. • Demonstrate repeatability of successful plug deployment and plug conformity to provide adequate tunnel seal. • Evaluate the impact of changes in plug oversizing ratio. • Establish a range of acceptable leakage rates measured during full-scale flooding simulations. | Full-scale surrogate Full-scale tunnel mockup Inspection and contact sensors, timing | Repeatable, acceptable deployment and conformance to tunnel geometry. |
Full scale Full-scale tunnel mockup Inspection and contact sensors, timing, and pressurized water testing | Repeatable, acceptable deployment and conformance to tunnel geometry, ability to withstand floodwater pressures with acceptable leakage rate and sufficient plug strength. | |||
Quarter scale Quarter-scale testing apparatus Inspection and pressurized water testing | Tradeoffs in plug frictional and sealing properties with adjustments in plug oversizing. | |||
Phase 3: 2013–2017 | • Refined prototype plug and container • An automated prototype inflation system • Full-pressure air inflation against floodwater pressure | • Move tunnel mockup to the plug manufacturer location for full-pressure air inflation testing. • Modify tunnel configuration to a representative configuration. • Integrate refined plug and container with prototype inflation system. • Demonstrate full-pressure air inflation. • Demonstrate repeatability of system performance in prototype configuration. • Demonstrate long-term system operation and performance. | Full scale Relocated, reconfigured tunnel mockup Inspection, timing, and pressurized floodwater testing | Reliable deployment and inflation within the required time; demonstration of the operation of the fully integrated system; verification of required frictional and sealing properties. Demonstration of ability for long-term (21 days) continuous performance of the system. |