Underground Sensing Strategies for the Health Assessment of Buried Pipelines

Buried lifeline infrastructure including pipelines, tunnels, power and communication lines, among others, are vital to ensuring the operation of the national economy. Permanent ground displacement (PGD) from earthquakes and landslides is the most serious hazard to buried pipelines, prompting often slow and expensive methods of damage localization before repairs can be made. Due to the importance of these buried lifelines, it is critical that low-cost and rapid methodologies for damage detection and localization be developed. Monitoring systems embedded in and around the pipeline are an obvious approach but typically suffer from the cost and obtrusiveness of long cable requirements. The primary goal of this chapter is to illustrate novel sensing methods that can serve as the basis for monitoring buried pipelines exposed to PGD. In particular, the chapter focuses on the monitoring of segmented concrete pipelines, which typically experience damage at their joints due to PGD. Wireless telemetry is evaluated to validate wireless sensors for buried applications, thus reducing greatly the cost of dense sensor systems in regions of high PGD risk. An overview of current buried pipeline sensing technology is made and three experimental full-scale PGD tests are conducted to evaluate pipeline motion and damage detection methodologies in segmented concrete pipelines. Real-time monitoring of joint rotations and translations by potentiometers as well as direct damage measures of joint regions by acoustic emission and conductive surface sensors were made. Strain gages were used to successfully portray global load transfer throughout the pipeline, validated by load cell measurements at the pipe ends. The combined sensor information is successfully used to create a hypothesis for the damage evolution process of buried segmented concrete pipelines under PGD and to validate the use of wireless sensors for buried pipeline monitoring