Abstract

Past observations showed that pipeline damages in liquefaction zones are significantly higher than the damages in areas where there was no liquefaction. Existing vulnerability relationships for the pipelines in liquefaction zones utilize parameters such as ground displacement, horizontal ground strain, angular distortion or both. These relationships are particularly useful in performance or risk assessment of pipeline systems. However, prediction of these parameters for pipeline damage estimates is difficult to perform and highly variable with current procedures. This paper proposes new correlations of asbestos cement (AC), cast iron (CI) and polyvinyl chloride (PVC) pipeline damage, expressed as repairs/km, with three different liquefaction parameters: liquefaction severity number (LSN), one-dimensional volumetric reconsolidation settlement (S-V1D), and liquefaction potential index (LPI). The pipeline damage data from 22 February 2011, Mw = 6.2 Christchurch earthquake and geotechnical information pertaining to liquefied area in Christchurch are utilized herein. Cone penetration test (CPT) based Boulanger and Idriss [1] liquefaction triggering procedure with 15th, 50th and 85th percentile cyclic resistance ratio (CRR) curves (corresponding to probabilities of liquefaction, PL, equal to 15%, 50%, and 85%) was used to calculate the parameters. It is shown that the relationships between AC, CI and PVC pipeline damages and LSN, S-V1D and LPI are strong, except for the correlation for AC pipeline damage versus LPI. Considering CI and PVC pipelines, both LSN and LPI correlations are comparable and slightly better than S-V1D correlations. Use of different probabilities of liquefaction triggering does not have significant effect on correlations with LSN and S-V1D whereas the same is not true for LPI correlations. Regarding the resilience of pipelines, PVC and AC pipelines performed the best and worst, respectively in all cases with CI pipelines in the middle. The correlations have the potential for use with existing or new liquefaction hazard maps for prediction of pipeline damage from future earthquakes. C1 [Toprak, Selcuk] Gebze Tech Univ, Dept Civil Engn, Kocaeli, Turkey. [Nacaroglu, Engin; Koc, Abdullah Cem; Manav, Yasemin] Pamukkale Univ, Dept Civil Engn, Denizli, Turkey. [van Ballegooy, Sjoerd; Torvelainen, Eric] Tonkin Taylor Ltd, 105 Carlton Gore Rd, Auckland 1023, New Zealand. [Jacka, Mike] Tonkin Taylor Ltd, 33 Parkhouse Rd, Christchurch 8042, New Zealand. [O'Rourke, Thomas Denis] Cornell Univ, Civil & Environm Engn Dept, Ithaca, NY 14853 USA.

Abstract

Recent earthquakes show that pipeline damage is severe in the areas where permanent ground deformations (e.g., liquefaction zones) occur. Ground movement hazard to pipeline systems can be assessed by using ground displacement measurements around the location of pipelines. There are many different ways of measuring ground displacements after an earthquake occur. This paper compares displacements measured in Avonside area, Christchurch, NZ, by using four different ways with respect to their effects on pipeline damage assessments. They are air photo, satellite, high resolution light detection and ranging (LiDAR) surveys data presented at 4- and 56-m grids acquired before and after the Mw6.2 22 February 2011 earthquake. Avonside area was in the liquefaction zones of the 22 February 2011 earthquake. Where possible, benchmark measurements were also included in the comparisons. In this study, the focus was on asbestos cement and cast iron water pipelines as the length of the pipelines and the number of damages in the study area was much higher compared to other pipe materials, providing sufficient repair rate data passing the screening criteria to develop linear regressions. The correlations between pipeline damage and lateral ground strains were developed by calculating the horizontal strains from these four different type displacements. The comparisons show that satellite imagery is good for estimating total movements but not so good for estimating lateral strains and conversely LiDAR surveys are not so good for estimating total movements, but much better for estimating lateral strains. Hence, pipeline damage correlations with LiDAR calculated strains provide higher determination coefficient (r2) value. The results of comparisons are presented and discussed. © 2018, Springer Science+Business Media B.V., part of Springer Nature.