Risk Assessment of Underground Utilities Subjected to Super Heavy Load (SHL) Applications in Overload Corridors

Vehicles transferring super heavy load (SHL) typically weigh several folds of the permissible weight limits set forth by regulatory agencies. Movement of such vehicles with multi-axle trailers can adversely affect the structural integrity of utilities buried underneath the roadway surface. This was the motivation for the authors to devise an approach to assess the potential risk against failure of underground utilities subjected to SHL movements in overweight corridors. To achieve this objective, our research team initially deployed portable weight-in-motion devices to ten sites with high frequency of SHLs in Texas. Subsequently, non-destructive field tests such as falling weight deflectometer and ground penetrating radar were performed for back-calculation of the pavement layer moduli. As-built plans were further reviewed to extract the pertinent information on utility characteristics. Subsequently, the field-derived data were in turn incorporated into a 3D finite element code for the determination of vertical deflection of utility at the crown under SHL movement, with realistic considerations of the tire-pavement contact stress distributions and pipe-soil interactions. Ultimately, the SHL-induced vertical deflection of utility was contrasted with maximum allowable deformation measures to characterize factor of safety against failure. The numerical simulation results showed that operation of SHLs with heavy axles and tires can potentially jeopardize the structural integrity of underground utilities across the state right-of-way, particularly if placed at shallow depths. Accordingly, buried utility risk analysis should be an integral component in risk management studies of transportation facilities servicing SHLs in overload corridors. The synthesized results can provide means to ensure safe operation of SHLs in highway networks accommodating underground utilities.