Underground structures

Many oil and gas pipelines are nearing the end of their design life but have many more years of production left. Despite the best designed and well maintained pipelines, the unavoidable defects such as metal loss due to corrosion, erosion, cracks and other means, structural integrity can be compromised.

Bhalla and Soh [2004] have discussed the feasibility of employing mechatronic conductance signatures of surface bonded PZT patches in monitoring the conditions of reinforced concrete structures subjected to base vibrations such as those caused by earthquakes and underground blasts. Mahadi [2008] reviews the development of SHM procedures, in particular, introducing optical fiber sensors (FBG) and electrical sensors (electrical gauges) embedded between composite wrapping and parent material (i.e. steel pipelines) that contain identified defects. A methodology for structural integrity and pipeline maintenance and repair is presented. A low cost fracture monitoring system for underground sewer pipelines has been reported by Todoroki et al [2004] using sensors made of fiber glass and carbon - epoxy composites. An experimental study is carried out by Mooney et al [2005] to explore the efficacy of vibration based SHM of earth structures, e.g., foundations, dams, embankments and tunnels to improve design, construction and performance.