Experimental evidence of wave-induced inhomogeneity in the strength of silty seabed sediments: Yellow River Delta, China

Abstract This paper presents the results of an experimental study in which the occurrence and evolution of inhomogeneity in the strength of a uniform-originated silty seabed were investigated. The pore pressure and penetration strength at different depths inside the seabed were observed during the experimental process under the weight of the soil and under the action of waves of different heights (H=5 cm, 10 cm, 15 cm). We found that a well-mixed silty seabed consolidates under the stress of its own weight, and its strength gradually increases as a result. Small wave action consolidates and strengthens the seabed and sediment. When the seabed is exposed to progressively higher waves, a fluidised response characterised by an arc-shaped boundary surface occurs on the seabed, and this response further controls the occurrence and evolution of the strength inhomogeneity of a uniform-origin seabed. The analyses clearly illustrate that features of seabed erosion and mass-transportation activity previously ascribed to increasing wave-current bed shear stress are controlled primarily by the process of wave-induced inhomogeneity in the strength of seabed sediments originating in the preceding period. In addition, the implications of the mechanism are explored.

[1]  W. E. Grabau,et al.  Sediment instability in the Mississippi River Delta , 1998 .

[2]  T. Kessel,et al.  Wave-induced liquefaction and flow of subaqueous mud layers , 1998 .

[3]  H. Shan,et al.  The effects of hydrodynamic conditions on geotechnical strength of the sediment in Yellow River Delta , 2011 .

[4]  B. Sumer,et al.  Experimental Validation of a Mathematical Model For Seabed Liquefaction Under Waves , 2011 .

[5]  Dong-Sheng Jeng,et al.  Wave-induced seabed instability in front of a breakwater , 1997 .

[6]  R. Wheatcroft,et al.  Size sorting of fine-grained sediments during erosion: Results from the western Gulf of Lions , 2008 .

[7]  Hocine Oumeraci,et al.  Liquefaction Phenomena underneath Marine Gravity Structures Subjected to Wave Loads , 2006 .

[8]  Malcolm D. Bolton,et al.  Physics of Liquefaction Phenomena around Marine Structures , 2006 .

[9]  Hiroyuki Yamazaki,et al.  MECHANISM OF WAVE-INDUCED LIQUEFACTION AND DENSIFICATION IN SEABED , 1990 .

[10]  G. H. Keller,et al.  Mass physical properties of Huanghe delta and Southern Bohai Sea near‐surface deposits, China , 1990 .

[11]  Fu-Ping Gao,et al.  Local scour and pore-water pressure around a monopile foundation under combined waves and currents , 2012 .

[12]  D. J. Henkel.  The Role of Waves in Causing Submarine Landslides , 1970 .

[13]  T. M. Parchure,et al.  Erosion of soft cohesive sediment deposits , 1985 .

[14]  R. Davidson‐Arnott,et al.  The effects of softening on nearshore erosion of a cohesive shoreline , 2000 .

[15]  Shiaw-Yih Tzang,et al.  Unfluidized soil responses of a silty seabed to monochromatic waves , 1998 .

[16]  Dong-Sheng Jeng,et al.  Response of a porous seabed around breakwater heads , 2008 .

[17]  M. Skafel,et al.  Flume experiments on the erosion of till shores by waves , 1994 .

[18]  P. Dong,et al.  A probabilistic analysis of random wave-induced liquefaction , 2011 .

[19]  Jørgen Fredsøe,et al.  Sinking/floatation of pipelines and other objects in liquefied soil under waves , 1999 .

[20]  S. P. Moores,et al.  Field observations and predictions of bed shear stressesand vertical suspended sediment concentration profiles in wave-current conditions , 1999 .

[21]  O. Madsen,et al.  Waves and currents over a fixed rippled bed 1. Bottom roughness experienced by waves in the presence , 1996 .

[22]  Jørgen Fredsøe,et al.  Wave Scour around a Pile in Sand, Medium Dense, and Dense Silt , 2007 .

[23]  D. Jeng.  Wave-induced sea floor dynamics , 2003 .

[24]  Yongfu Sun,et al.  Wave-induced shallow slides and their features on the subaqueous Yellow River delta , 2009 .

[25]  E. Toorman,et al.  The characterisation of cohesive sediment properties , 1993 .

[26]  G. H. Keller,et al.  Storm wave reactivation of a submarine landslide , 1989, Nature.

[27]  H. Sekiguchi,et al.  Analysis of wave-induced liquefaction of sand beds , 2001 .

[28]  S. Leroueil,et al.  Strength development with burial in fine-grained sediments from the Saguenay Fjord, Quebec , 1995 .

[29]  M. S. Rahman.  Wave‐induced instability of seabed: Mechanism and conditions , 1991 .

[30]  M. Foda,et al.  Resonant fluidization of silty soil by water waves , 1994 .

[31]  M. Richardson,et al.  The effects of biological and hydrodynamic processes on physical and acoustic properties of sediments off the Eel River, California , 2002 .

[32]  G. H. Keller,et al.  Processes of marine dispersal and deposition of suspended silts off the modern mouth of the Huanghe (Yellow River) , 1990 .

[33]  G. H. Keller,et al.  Active slope failure, sediment collapse, and silt flows on the modern subaqueous Huanghe (Yellow River) delta , 1986 .

[34]  P. Lesueur,et al.  Seasonal variations in the characteristics of superficial sediments in a macrotidal estuary (the Seine inlet, France) , 2003 .

[35]  Ole Secher Madsen,et al.  Waves and currents over a fixed rippled bed: 2. Bottom and apparent roughness experienced by currents in the presence of waves , 1996 .

[36]  H. Bolton Seed,et al.  Wave‐induced pore pressure in relation to ocean floor stability of cohesionless soils , 1978 .

[37]  善 功企,et al.  Mechanism of wave-induced liquefaction and densification in seabed. , 1990 .

[38]  Mark Randolph,et al.  Interaction forces between pipelines and submarine slides — A geotechnical viewpoint , 2012 .

[39]  B. N. Tomlinson,et al.  Laboratory investigations into wave period effects on sand bed erodibility, under the combined action of waves and currents , 1995 .

[40]  Chiang C. Mei,et al.  Note on sediment sorting in a sandy bed under standing water waves , 2007 .

[41]  G. H. Keller,et al.  Sediment thixotropy and submarine mass movement, Huanghe Delta, China , 1991 .

[42]  R. Wheatcroft,et al.  Oceanic flood deposits on the northern California shelf: large-scale distribution and small-scale physical properties , 2000 .

[43]  V. N. Sokolov,et al.  Structure formation in clay sediments , 1978 .

[44]  Jørgen Fredsøe,et al.  The sequence of sediment behaviour during wave‐induced liquefaction , 2006 .

[45]  S. Tzang,et al.  Laboratory flume studies on monochromatic wave-fine sandy bed interactions: Part 1. Soil fluidization , 2006 .

[46]  Dong-Sheng Jeng,et al.  A new approximation for pore pressure accumulation in marine sediment due to water waves , 2007 .

[47]  T. Hsu,et al.  Laboratory flume studies on monochromatic wave-fine sandy bed interactions Part 2. Sediment suspensions , 2009 .