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

Advances in Mechanical Engineering

Ding

et al. 2016

Wave-seabed interaction has become a big concern of coastal researchers and engineers in the past decades as it may largely contribute to the seabed instability and failure of marine foundations. A series of laboratory experiments are carried out in a wave flume to study the wave-driven pore-water pressure in a sandy seabed and the attenuation of wave height. Waves propagating over a sandy seabed lead to oscillatory excess pore-water pressures within the porous seabed. Amplitude of pore-water pressure within the seabed decreases toward the bottom. A phase lag of pore-water pressure is clearly observed, and it contributes to net upward pressure related to seabed instability. Height of the incident wave is reduced as part of wave energy is dissipated by bottom friction, and a maximum attenuation of the incident wave height is up to 7.23% in the experiments. The influences of wave period and height of the incident wave on porewater pressure and wave attenuation are also analyzed and discussed.

Section: Introductionmentioning

confidence: 99%

Experimental investigation of wave-driven pore-water pressure and wave attenuation in a sandy seabed

Advances in Mechanical Engineering

Ding

et al. 2016

“…During Stage III, the sediment liquefaction interface essentially remained at a stable level. In this stage, the structure of the sediment was continuously strengthened as a result of gravitational consolidation and drainage of pore water in sediments, and the sediment particles became more compact [25]. Thus, liquefaction was not observed in this post-liquefied sediment [40].…”

Section: Variations Of Sscs In the Overlying Watermentioning

confidence: 93%

Migration and Diffusion of Heavy Metal Cu from the Interior of Sediment during Wave-Induced Sediment Liquefaction Process

Lü

Jia

et al. 2019

JMSE

Sediments are an important sink for heavy metal pollutants on account of their strong adsorption capacity. Elevated content of Cu was observed in the Chengdao area of the Yellow River Delta, where the surface sediment is mainly silt and is prone to be liquefied under hydrodynamic forces. The vertical transport of fine particles, along with pore water seepage, during the liquefaction process could promote the migration and diffusion of Cu from the interior of sediment. The present study involved a series of wave flume experiments to simulate the migration and diffusion of Cu from the interior of sediment in the subaqueous Yellow River Delta area under wave actions. The results indicated that sediment liquefaction significantly promoted the release of Cu from internal sediment to overlying water. The variations of Cu concentrations in the overlying water were opposite to the suspended sediment concentrations (SSCs). The sediment liquefaction caused high initial rises of SSCs, but led to a rapid decline of dissolved Cu concentration at the initial period of sediment liquefaction due to the adsorption by fine particles. Afterwards, the SSCs slightly increased and then gradually decreased. Meanwhile, the dissolved Cu concentration generally kept increasing under combined effects of intensively mix of sediment and overlying water, pore water seepage, and desorption. The dissolved Cu concentration in the overlying water during sediment liquefaction phase was 1.5–2.2 times that during the consolidation phase. Sediment liquefaction also caused vertical diffusion of Cu in sediment and the diffusion depth was in accordance with the liquefaction depth. The results of the present study may provide reference for the environmental management in the study area.

“…Xu et al (2012) performed dynamic triaxial experiments on sediment samples with clay contents of 3%, 9%, 15%, and 21% and found an inflection point at a clay content of 9% on the development of pore-water pressure under dynamic loading actions; sediment with clay contents higher than 9% had a higher anti-liquefaction capacity (i.e., maximum liquefaction index) than sediment with a clay content lower than 9%, roughly consistent with the findings of a critical value at 13% clay content in this study. Meanwhile, in a flume experiment conducted by Liu et al (2013b), waves had a high attenuation degree on seabed sediment with a high clay content 1904-1929 1929-1934 1947-1964 1964-1976 1976-1996 compared with sediment with a low clay content, which also indicated that sediment with higher clay contents liquefied less readily. In addition to the sediment's physical properties, sedimentary history (not considering human disturbance) was another important factor influencing sediment liquefaction properties.…”

Section: Influencing Factors Of Sediment Liquefactionmentioning

confidence: 99%

“…4). As shown by the close relationship between sediment particle composition and liquefaction, sediments with low clay contents could be more easily liquefied by wave loadings, while sediments with older deposition histories had lower clay contents due to the coarsening process of sediment under marine hydrodynamic conditions over time (Liu et al 2013b(Liu et al , 2017. Therefore, sedimentary history is an important factor in sediment liquefaction due to the resulting variations in sediment particle composition, which can directly affect sediment anti-liquefaction properties.…”

Section: Influencing Factors Of Sediment Liquefactionmentioning

confidence: 99%

Experimental dynamic sediment behavior under storm waves with a 50 year recurrence interval in the Yellow River Delta

Liu

Zheng

et al. 2019

Anthropocene Coasts

The dynamic response of marine sediment from the Yellow River under extreme sea conditions is attracting increasing academic and engineering attention because of the high occurrence frequency of geologic hazards. To simulate the dynamic response process of sediment samples under waves with a 50 year recurrence interval, we collected undisturbed sediment samples from six sites on the intertidal flats of the Yellow River Delta and performed dynamic triaxial experiments to analyze the pore-water pressure and liquefaction process. The empirical patterns of pore-water pressure generation and ranges of sediment parameters were determined, and the factors affecting sediment liquefaction were discussed. Under the cyclic loading of waves with a 50 year recurrence interval, the pore pressure response of sediments at a depth of 4 m could be generalized into three stages: rapid growth, slow growth, and stable maintenance. Moreover, the build-up of pore-water pressure was effectively represented by a logarithmic growth model. The liquefaction characteristics of sediment in the Yellow River Delta were more related to its plasticity index, mean particle size, and clay, silt, and sand contents, as well as the sedimentary history. These factors should be considered in the development of disaster assessment models in coastal environments of the Yellow River Delta.