Mitigating the Risk of Failure during Construction Live Loading on Prestressed Concrete Cylinder Pipe (PCCP)

Managing buried assets and risk during construction activities is critical for utility owners. This study provides innovative engineering techniques to assess the risk of building a roadway over a pipeline. While traditional methods could have been employed for the project discussed in this study, the asset’s criticality deemed it a high-risk, thus managing the risk was key to delivering a successful project. This study describes the project background, pipeline, and method employed to manage the risk of the project. This study also provides a procedure to examine if a pipe, as originally designed, can withstand the new loading conditions generated from the construction activities and from the conditions that will prevail post-construction. The proposed method determines the maximum allowable live loads for the different amounts of earth cover. For the case study, a 1372-mm prestressed concrete cylinder pipe (PCCP) under 0.3, 0.7, and 1.5 meters of earth cover and construction loading was analyzed. The impact of construction activities on the PCCP was determined by monitoring the level of stresses and strains in the various components of the pipe during different construction loading while varying the number of broken prestressing wire wraps. Based upon the results obtained, the threshold depth of cover to satisfy the design requirement for undamaged pipes was calculated. Also, to prevent additional stress on the PCCP, the controlling threshold was considered as the micro-cracking limit which was developed by nonlinear finite element analysis (FEA). The micro-cracking limit mitigates the level of risk and diminishes the level of stresses to the PCCP with broken wire wraps during construction activities.