Mitigation systems for the uplift of buried pipelines in liquefiable soils under repeated shaking through model tests

Abstract

The effectiveness of remedial measures for the stability of onshore buried pipelines against the uplift mechanism induced by soil liquefaction, in the event of an earthquake, is investigated through 1-g shaking table tests. This study aims at proposing mitigation solutions that may be an alternative to the already existing and currently adopted systems, accounting for a set of requirements that cannot be omitted in the context of long tracks and variable soil conditions, looking at the cost-effectiveness too. In this paper, the performance of three systems is described, which consist of a possible arrangement of drainpipes in a typical pipe trench, a gravel bag placed above the pipeline and possibly connected to each other, or geogrids installed horizontally in the soil deposit above the pipe. The working principle of these systems is to contrast the development of the mechanism responsible for the uplift of the embedded pipe and their performance is verified under repeated shaking, thus accounting for the multiple earthquakes that may occur in the time span of the pipe design life. Results of the model tests show that both gravel bag and geogrids performed well and could be employed as a remedial against uplift in the industry.