Abstract
A novel scour protection approach for pipeline using the Ionic Soil Stabilizer (ISS) solidified soil was proposed in this study. The ISS-solidified slurry can be poured adjacent to the pipeline immediately after it was placed, or in the growing scour holes. In the present study, the first type was utilized as the scour protection layer around the pipeline. A series of laboratory flume tests were conducted to validate the protective capacity of ISS-solidified slurry for the pipeline in waves and combined waves and current. Then, the scanning electron microscope (SEM) tests and pore size tests were carried out, respectively, to investigate the mechanism of ISS-solidified slurry for scour protection around the pipeline. Finally, the effects of the ISS-solidified layer for liquefaction stability of non-cohesive subsoil were evaluated. The results indicated that the ISS-solidified slurry is a reliable, economic approach for scour protection around pipelines in the ocean environment. It is noteworthy that if a non-cohesive soil layer underlies the ISS-solidified slurry, it is vulnerable to suffer accumulated liquefaction due to the dense crust structure of the ISS-solidified layer, so the adverse effects for accumulated liquefaction should be considered carefully due to the set of the ISS-solidified layer.
Highlights
Submarine pipelines are widely adopted to transport the oil, gas, hydrocarbons and other liquids in ocean engineering [1,2]
When a pipeline is placed on the seabed, it will suffer the action of waves and current, resulting in the local scour occurring in the vicinity of the pipeline [3,4]
The results indicated that the piping caused by the pressure difference between the upstream and downstream pipeline edges plays a dominant role in the onset of scour below the pipeline
Summary
Submarine pipelines are widely adopted to transport the oil, gas, hydrocarbons and other liquids in ocean engineering [1,2]. The sediments erosion rate varies greatly along the pipeline because of the discrepancy of soil properties, which will cause pipeline suspension in the local regions, so it still needs further improvement in practice The latter countermeasure is mainly placing protection materials or installing additional structures adjacent to the pipeline, such as gravels, rocks, geotextiles, concrete mattresses, impermeable rigid (or rubble) plates [9,10,26,27,28]. These measures effectively reduce the pressure gradient beneath the pipeline, and the piping is hard to occur. ISS-solidified slurry as scour protection layer was discussed comprehensively
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