Study On Formation And Development Of Silt Flows Under Waves On The Yellow River Subaqueous Delta

There are abundance of silt flow gullies on silt gentle-slope of the Yellow River Subaqueous Delta. On the silt coasts of the Yellow River Delta, there are many important engineering establishments, for example: kinds of offshore platforms, cables and pipelines. Silt flows would erode and cut near-surface strata, and create great harm to shallow buildings, cables and pipelines, so research is carried out for solving those.Taking silt in the Yellow River Delta as the research object, formation, development and their phenomenon of Silt Flows under Waves were studied by wave flume experiment and theoretical analysis.The indoor flume experiment shows that moving silt flow body oscillates in whole with wave, and the bigger wave is, the more extensive the moving soils extending area, and there are small gullies and scarps on the shallow soil bed after the motion stability, and those are similar to silt flow gullies on the Yellow River Subaqueous Delta.acquiring silt flow formation and motion mechanism by the flume experiment and in-situ data analysis, it is that weak strength soils which pass critical cyclic stress ratio are sheared by wave and oscillates in whole, and then act on Surrounding stable soils with waves, and surrounding soils pass critical cyclic stress ratio also, strength weakening, and sheared by wave into moving soils.In the extending process, water content of moving soils increases . By sediment concentration determination in the water of the flume experiment, it's be found that primary formation of silt flows makes sediment concentration in the water increasing quickly, and the bigger waves are, the more the moving soils mass is, the bigger sediment concentration in the water is. Initial formulas of depth of the moving soils and unit width quantity of sediment in the length between single wave crest and trough have be acquired by Analyzing and fitting the relation among wave element, depth of the moving soils and unit width quantity of sediment in the length between single wave crest and trough. Initial formulas are corrected and verified by in-situ data in chendao sea field into final formulas.