The impact of wave loads and pore-water pressure generation on initiation of sediment transport

1985 ◽  
Vol 5 (3) ◽  
pp. 177-183 ◽  
Author(s):  
Edward C. Clukey ◽  
Fred H. Kulhawy ◽  
Philip L. -F. Liu ◽  
George B. Tate
Keyword(s):  
Sediment Transport ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Wave Loads ◽  
The Impact

An Experimental Study on the Wave-Induced Topographic Change in Artificial Shallows: Focusing on the Effects of Pore-Water Pressure on Sediment Transport

2014 ◽  
Vol 56 (2) ◽  
pp. 1450008-1-1450008-21 ◽  
Author(s):  
Tomoaki Nakamura ◽  
Yuta Nezasa ◽  
Yong-Hwan Cho ◽  
Ryo Ishihara ◽  
Norimi Mizutani
Keyword(s):  
Experimental Study ◽  
Sediment Transport ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Wave Induced

scholarly journals Analysis of plant root–induced preferential flow and pore-water pressure variation by a dual-permeability model

2017 ◽  
Vol 54 (11) ◽  
pp. 1537-1552 ◽  
Author(s):  
Wei Shao ◽  
Junjun Ni ◽  
Anthony Kwan Leung ◽  
Ye Su ◽  
Charles Wang Wai Ng
Keyword(s):  
Slope Stability ◽  
Pore Water ◽  
Factor Of Safety ◽  
Preferential Flow ◽  
Pore Water Pressure ◽  
Plant Root ◽  
Water Pressure ◽  
Planting Density ◽  
Permeability Model ◽  
The Impact

Vegetation can affect slope hydrology and stability via plant transpiration and induced matric suction. Previous work suggested that the presence of plant roots would induce preferential flow, and its effects may be more significant when the planting density is high. However, there is a lack of numerical studies on how planting density affects soil pore-water pressure and shear strength during heavy rainfall. This study aims to investigate the impact of plant root–induced preferential flow on hydromechanical processes of vegetated soils under different planting densities. Two modelling approaches, namely single- and dual-permeability models, were integrated with an infinite slope stability approach to simulate pore-water pressure dynamics and slope stability. Laboratory tests on soils with two different planting densities for a plant species, Schefflera heptaphylla, were conducted for numerical simulations. The single-permeability model overestimated the pore-water pressure in shallow soil and underestimated the infiltration depth. The dual-permeability model, which is able to model the effects of preferential flow, can better capture the observations of rapid increase of pore-water pressure and deeper pressure response in the vegetated soil. However, caution should be taken on the choice of pore-water pressure when using the dual-permeability model to assess the factor of safety. The dual-permeability model using the pore-water pressure in the preferential flow domain and that in the matrix domain would result in a lower and higher factor of safety, respectively.

scholarly journals Experimental Study on Pore Water Pressure and Sediment Transport by Oscillatory Flow with Pressure Change

1996 ◽  
Vol 12 ◽  
pp. 249-253
Author(s):  
Toshihiko Yamashita ◽  
Shinichi Ito ◽  
Akira Yamamoto ◽  
Takaaki Minamimura ◽  
Mikio Kuroki
Keyword(s):  
Experimental Study ◽  
Sediment Transport ◽  
Pore Water ◽  
Oscillatory Flow ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Pressure Change

scholarly journals The Drainage Consolidation Modeling of Sand Drain in Red Mud Tailing and Analysis on the Change Law of the Pore Water Pressure

2014 ◽  
Vol 2014 ◽  
pp. 1-10
Author(s):  
Chuan-sheng Wu
Keyword(s):  
Differential Equation ◽  
Pore Water ◽  
Red Mud ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Control Variable ◽  
Separation Distance ◽  
Dam Failure ◽  
Coefficient Of Consolidation ◽  
The Impact

In order to prevent the occurring of dam failure and leakage, sand-well drainages systems were designed and constructed in red mud tailing. It is critical to focus on the change law of the pore water pressure. The calculation model of single well drainage pore water pressure was established. The pore water pressure differential equation was deduced and the analytical solution of differential equation using Bessel function and Laplace transform was given out. The impact of parameters such as diameterd, separation distancel, loading rateq, and coefficient of consolidationCvin the function on the pore water pressure is analyzed by control variable method. This research is significant and has great reference for preventing red mud tailings leakage and the follow-up studies on the tailings stability.

scholarly journals Impact-Induced Liquefaction Mechanism of Sandy Silt at Different Saturations

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Heng Li ◽  
Zhao Duan ◽  
Chenxi Dong ◽  
Fasuo Zhao ◽  
Qiyao Wang
Keyword(s):  
Shear Strength ◽  
Moisture Content ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Silty Sand ◽  
Sandy Silt ◽  
Loess Landslides ◽  
Mechanism Of Impact ◽  
The Impact

Landslide-induced liquefaction has received extensive attention from scholars in recent years. In the study of loess landslides in the southern Loess Plateau of Jingyang, some scholars have noted the liquefaction of the near-saturated sandy silt layer that is caused by the impact of loess landslides on the erodible terrace. The impact-induced liquefaction triggered by landslides is probably the reason for the long-runout landslides on the near-horizontal terrace. In order to reveal the mechanism of impact-induced liquefaction, this paper investigates the development of pore pressure and the impact-induced liquefaction of sandy silt under the influence of saturation through laboratory experiments, moisture content tests, and vane shear tests. It has been found that both the total pressure and pore water pressure undergo a transient increase and decrease at the moment of impact on the soil, which takes 40–60 ms to complete and only about 20 ms to arrive at the peak. Moreover, silty sand with a saturation of more than 80° was liquefied under the impact, and the liquefaction occurred in the shallow layer of the soil body. The shear strength of the liquefied part of the soil is reduced to 1.7∼2.8 kPa. Soils with lower saturation did not liquefy. The mechanism of the impact-induced liquefaction can be described as follows: under impact, the water in the soil gradually fills the pores of the soil body as the pore size decreases, and when the contact between the soil particles is completely replaced by pore water, the soil body loses its shear strength and reaches a liquefied state. Soils in the liquefied state have a very high permeability coefficient, and the water inside the soil body migrates upward as the particles settle, resulting in high-moisture content in the upper soil.

scholarly journals Experimental Study on Mechanism of Wave-Induced Liquefaction of Sand-Clay Seabed

2020 ◽  
Vol 8 (2) ◽  
pp. 66
Author(s):  
Jun Zhang ◽  
Qin Jiang ◽  
Dongsheng Jeng ◽  
Changkuan Zhang ◽  
Xindi Chen ◽  
...  
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Sand Particle ◽  
Wave Loads ◽  
Micro Structure ◽  
Wave Flume ◽  
Contact Points ◽  
Test Soil ◽  
Wave Induced

In this study, a series of laboratory experiments for the response of wave induced clay-sand seabed were carried out to clarify the mechanism of liquefaction of clayey seabed. The experiments were conducted in an 80 m long wave flume. In the tests, the sand-clay beds were mixed with various clay contents (CC) from 0.5% to 15% and were tested for given wave conditions. The pore water pressure and the water elevation were measured in each test. Soil properties tests and scanning electron microscope (SEM) experiments on different seabed samples were carried out to further explore the mechanism of liquefaction. The experimental results indicated that the amplitude and accumulation of the excess pore water pressure (EPP) varied with different CC in the sand-clay bed. With the introduction of CC, micro-structure and properties (such as permeability and compressibility) of bed soils changed. Sand-clay bed presented more susceptibility to liquefy compared with pure sand bed. CC promoted seabed liquefaction, even if the added amount was very small (CC is 0.5%), however when CC exceeded a certain value (10% in this study), the mixed bed will not be liquefied. This phenomenon can be well explained by the micro-structure of sand-clay bed. CC within a sandy seabed, does not only affect the permeability, but also change the compressibility of seabed soils. For example, the microfabric of seabed vulnerable to liquefaction is loose. Clay aggregations generally gathered at the sand particle contact points. This microfabric is easily compressed under wave loads and allowed pore water to flow, resulting in the accumulation of pore water pressure. On the other hand, the microfabric of seabed that was resistant to liquefaction appeared to be more compact. Due to clay-filled gaps between the sand particles, the pore water is more difficult to flow when seabed was compressed. Furthermore, the tendency of seabed liquefaction is closely related to CC.

scholarly journals Dynamic Pressure of Seabed around Buried Pipelines in Shallow Water

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Changjing Fu ◽  
Guoying Li ◽  
Tianlong Zhao ◽  
Donghai Guan
Keyword(s):  
Shallow Water ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Dynamic Pressure ◽  
Water Pressure ◽  
Great Influence ◽  
Irregular Waves ◽  
Pressure Amplitude ◽  
Wave Loads ◽  
Buried Pipelines

Due to the obvious nonlinear effect caused by the shallow waves, the nonlinear wave loads have a great influence on the buried pipelines in shallow water. In order to ensure their stability, the forces on the pipelines that resulted from nonlinear waves should be considered thoroughly. Based on the Biot consolidation theory and the first-order approximate cnoidal wave theory, analytical solutions of the pore water pressure around the buried pipelines in shallow water caused by waves are firstly derived in this paper. The dynamic response of the seabed around the pipelines under the action of irregular waves is explored in laboratory, and the results are compared with the analytical ones. Experiments show that the maximum value of the pore water pressure is at the upper part of the pipelines, and the value at the bottom of the pipelines is the minimum. The pore water pressure amplitude at the upper half of the seabed that arises from waves has a larger fluctuation, and the amplitude at the lower half remains stable. For the sandy seabed, the pore water pressure at the same depth changes over time, with the fluctuating amplitude, and the theoretical values meet well with the test results.

TIME TO THE END OF PRIMARY CONSOLIDATION (EOP) OF SOFT CLAYEY SOILS: CONCERNING THE EFFECT OF ATTERBERG’S LIMIT AND CYCLIC LOADING HISTORY

2019 ◽  
Vol 128 (2B) ◽  
pp. 29-41
Author(s):  
Trần Thanh Nhàn
Keyword(s):  
Cyclic Loading ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Clayey Soils ◽  
Loading History ◽  
Cyclic Shear ◽  
Wide Range ◽  
Primary Consolidation ◽  
Time Required

In order to observe the end of primary consolidation (EOP) of cohesive soils with and without subjecting to cyclic loading, reconstituted specimens of clayey soils at various Atterberg’s limits were used for oedometer test at different loading increments and undrained cyclic shear test followed by drainage with various cyclic shear directions and a wide range of shear strain amplitudes. The pore water pressure and settlement of the soils were measured with time and the time to EOP was then determined by different methods. It is shown from observed results that the time to EOP determined by 3-t method agrees well with the time required for full dissipation of the pore water pressure and being considerably larger than those determined by Log Time method. These observations were then further evaluated in connection with effects of the Atterberg’s limit and the cyclic loading history.

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