Geogrids as a Remedial Measure for Seismic-Liquefaction Induced Uplift of Onshore Buried Gas Pipelines
The use of geogrids in geotechnical engineering is increasing over the years and it has been mostly studied in the applications of steep slopes, retaining structures and embankments constructed over soft foundations. The increase in liquefaction resistance for sandy soils by using fiber reinforcements started to be considered but the use of geogrids to mitigate liquefaction phenomenon needs to be further investigated. Here, the application of geogrids sheets to prevent the seismic-liquefaction induced uplift of a buried onshore gas pipeline in saturated sandy soil is described by the results of 1-g shaking table tests performed at the geotechnical laboratory of the University of Tokyo in a model scale of 1:10. A Silica Sand with a relative density of ~50% is used, a 40 cm long DN100 PVC pipe with an apparent unit weight of 0.68 g/cm3 is buried in the soil model and 3 geogrid sheets of dimensions 30 cm by 40 cm with an interlayers distance of 3.5 cm are placed above the pipe as remedial measure. Applying sinusoidal shaking with different amplitude, the model response is studied. Geogrids resulted an effective tool to mitigate pipe displacement in case of liquefaction.
KeywordsPipeline Uplift Liquefaction Shaking table Remedial measure Geogrids
We would like thanking Ms. M. Nucciarone and Mr. E. Di Biase, University of Molise, for their precious help in models’ preparation. The Saipem corporation (Italy) is warmly acknowledged for financial and technical support. A special thanks to all the UTokyo geotechnical lab members for helping and support for tests and their interpretation.
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