Friction characteristics of confined inflatable structures

The availability of high-strength fabrics and progress in the development of large-scale inflatable technology made possible the creation of temporary and quickly deployable structures for protection of underground infrastructure. Inflatable structures are relatively lightweight and portable, and can maintain the required rigidity while in operation. These benefits have prompted the development of inflatable structures for use in confined spaces, such as tunnels and large-diameter pipes to act as barriers for containing flooding with minimal infrastructure modification. This work presents experimental results obtained from the evaluation of frictional characteristics of the fabric material that constitute the structural membrane of confined inflatable structures developed for protection of underground transportation tunnels and other large conduits. Friction tests at coupon level and slippage tests in a reduced-scale inflatable structure were performed in order to evaluate the frictional characteristics of Vectran webbings. Tests at coupon level were performed to determine the friction coefficient for different surface types and conditions. Tests with the reduced-scale inflatable structure contributed to the understanding of the friction characteristics at system level when subjected to different pressurization or depressurization sequences designed to induce slippage. Test results indicate that friction coefficient values at coupon level are about 29 percent higher than values derived from reduced-scale tests.