Analytical Solution for the Wave-Induced Excess Pore-Pressure in a Finite-Thickness Seabed Layer

1995 ◽  
Author(s):  
Waldemar MAGDA
Keyword(s):  
Analytical Solution ◽  
Pore Pressure ◽  
Finite Thickness ◽  
Excess Pore Pressure ◽  
Wave Induced ◽  
Excess Pore

scholarly journals Experimental Study on the Distribution of Wave-Induced Excess Pore Pressure in a Sandy Seabed around a Mat Foundation

2019 ◽  
Vol 7 (9) ◽  
pp. 304
Author(s):  
Yuan ◽  
Liao ◽  
Zhou
Keyword(s):  
Pore Pressure ◽  
Numerical Study ◽  
Experimental Results ◽  
Excess Pore Pressure ◽  
Offshore Platforms ◽  
Pressure Area ◽  
Mat Foundation ◽  
Mat Foundations ◽  
Wave Induced ◽  
Excess Pore

Mat foundations are widely used in jack-up offshore platforms to support and transfer loads. Regarding mat foundations working on the seabed, the excess wave-induced pore pressure is critical to seabed stability, which may finally cause structural failure. Therefore, it is important to investigate the distribution of the excess pore pressure in the seabed around the mat foundation. In this study, experiments were performed to study the excess pore pressure distribution around a mat foundation in scale considering the true load state by recording wave profiles and pore pressures inside a sandy seabed. To guarantee the reliability of experiments, a numerical study was conducted and compared with the experimental results. Experimental results indicate that with the existence of the mat foundation, the excess pore pressure is higher at the region, the range of which is the width of the model mat (Wm) before the structure. The maximum pore pressure appears at 0.55 Wm in front of the center of the mat foundation. In addition, the current significantly increases the range of high pore pressure area and the amplitude of the excess pore pressure. As the mat orientation changes, the position of the maximum pore pressure changes from the front to the edge of the mat.

HHT Analysis on Pore Pressure Dissipation of Wave-Induced Fluidization in a Sandy Bed

2011 ◽  
Author(s):  
Shiaw-Yih Tzang ◽  
Yung-Lung Chen ◽  
Shan-Hwei Ou
Keyword(s):  
Pore Pressure ◽  
Soil Layer ◽  
Excess Pore Pressure ◽  
Pressure Measurements ◽  
Flume Tests ◽  
Dissipation Mechanism ◽  
Frequency Components ◽  
Excess Pore Pressures ◽  
Wave Induced ◽  
Excess Pore

Wave-induced pore pressure variations during the stage of increasing excess pore pressure consist of the mechanism of generation of fluidization. Moreover, in post-fluidization stage, pore pressure variations not only reveal the dissipation mechanism of fluidization but also the wave-fluidized bed interactions. Past results from a series of lab flume tests have further illustrated that pore pressure variations in a fluidized response are nonlinear and nonsataionary. Hence, the HHT method was further applied to analyze the pore pressure measurements in this study. The results demonstrate that after the dissipation of excess pore pressures the amplitudes of fundamental and higher-frequency components begin to decay. Meanwhile, the amplified amplitudes of fundamental and higher-frequency components during fluidization response would decrease with decreasing thickness of fluidized soil-layer in consecutive tests.

Analytical Solution and Consolidation Analysis of One-dimensional Large Strain Consolidation Differential Equation

2020 ◽  
Vol 15 ◽  
Author(s):  
Shijia Liu ◽  
Huifeng Su ◽  
Tao Yu ◽  
Shuo Zhao ◽  
Zhicheng Cui
Keyword(s):  
Analytical Solution ◽  
Pore Pressure ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Control Variable ◽  
Excess Pore Pressure ◽  
Excess Pore Water Pressure ◽  
One Dimensional ◽  
Small Strains ◽  
Excess Pore

Abstract:: According to the universal one-dimensional consolidation equation introduced by Gibson, the governing equation with the excess pore water pressure as the control variable is derived, and the Fourier series solution under the boundary condition of single-sided drainage is deduced in detail by the standard mathematical physical method. It verifies the correspondence between the analytical solution and the numerical solution from a theoretical point of view. Using this analytical solution, the nonlinear distribution of the excess pore pressure along the depth direction is obtained, and the traditional small strain consolidation is compared in terms of the average consolidation degree and the final settlement. Soft soil foundation, large deformation foundation Derive a consolidation equation for soft soils with large deformations using the super-static pore pressure as the control variable Formula derivation, Example analysis Based on Gibson's general equation of consolidation and its theory, the detailed derivation process of differential equations with excess pore water pressure as the control variable is given. According to the example, the image shows the distribution of excess pore pressure with depth, and comparative analysis of large and small strains, If all other conditions are the same, When mv1=1 MPa-1, it can be calculated according to the large and small strains, but when mv1≥3MPa-1, the two errors are large, The calculation must be considered separately.

scholarly journals Contribution of Pumping Action of Wave-Induced Pore-Pressure Response to Development of Fluid Mud Layer

2019 ◽  
Vol 7 (9) ◽  
pp. 317 ◽  
Author(s):  
Yang ◽  
Zhu ◽  
Liu ◽  
Sun ◽  
Ling ◽  
...  
Keyword(s):  
Pore Pressure ◽  
Fine Particles ◽  
Pore Water Pressure ◽  
Theoretical Calculations ◽  
Water Pressure ◽  
Pressure Response ◽  
Excess Pore Pressure ◽  
Pore Pressure Response ◽  
Wave Induced ◽  
Excess Pore

To investigate the vertical migration response of fine sediments, the pore pressure response of the silty seabed under the action of waves was tested. Under the action of waves, there is an obvious pumping phenomenon in the sludge accumulated by pore pressure. The excess pore water pressure caused by the waves in the seabed is unevenly distributed with respect to depth and there is an extreme value of up to 1.19 kPa. The pressure affects the liquefaction properties of the sludge. According to instantaneous-liquefaction judgment, the liquefaction of surface soil occurs, but the soil is not completely liquefied. Using theoretical calculations, the vertical source supply of floating mud development was analyzed. The pumping effect of the wave-induced excess pore pressure manifests in two aspects, as follows: (1) The centralized migration of splitting channels, which is visible to the naked eye, and (2) the general migration of fine particles between particle gaps at the mesoscopic level, which accounts for up to 22.2% of the migration of fine particles.

scholarly journals Discrete element numerical simulation on the accumulation of wave-induced excess pore pressure in silty seabed sediments

2020 ◽  
Vol 570 ◽  
pp. 022063
Author(s):  
Y S Li ◽  
X L Liu ◽  
C Liu ◽  
C Hu ◽  
H Q Tian ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Pore Pressure ◽  
Discrete Element ◽  
Excess Pore Pressure ◽  
Wave Induced ◽  
Seabed Sediments ◽  
Excess Pore

Vibro-Stone Column Reinforcement Mechanism and Numerical Analysis

2012 ◽  
Vol 446-449 ◽  
pp. 1940-1943
Author(s):  
Yang Liu ◽  
Hong Xiang Yan
Keyword(s):  
Numerical Simulation ◽  
Numerical Analysis ◽  
Pore Pressure ◽  
Numerical Procedure ◽  
Numerical Results ◽  
Excess Pore Pressure ◽  
Stone Column ◽  
Reinforcement Mechanism ◽  
Consolidation Theory ◽  
Excess Pore

Numerical simulation of vibro-stone column is taken to simulate the installation of vibro-stone column. A relationship based on test is adopted to calculate the excess pore pressure induced by vibratory energy during the installation of vibro-stone column. A numerical procedure is developed based on the formula and Terzaghi-Renduric consolidation theory. Finally numerical results of composite stone column are compared single stone column.

scholarly journals The consolidation of soils under stochastic initial excess pore pressure

1993 ◽  
Vol 17 (11) ◽  
pp. 609-612 ◽  
Author(s):  
A.A. Darrag ◽  
M.A. El Tawil
Keyword(s):  
Pore Pressure ◽  
Excess Pore Pressure ◽  
Excess Pore

Pumping effect of rainfall-induced excess pore pressure on particle migration

2021 ◽  
pp. 100669
Author(s):  
Feng GAO ◽  
Xuzhen HE ◽  
Sheng ZHANG
Keyword(s):  
Pore Pressure ◽  
Particle Migration ◽  
Excess Pore Pressure ◽  
Pumping Effect ◽  
Excess Pore

scholarly journals How deep does sand deposits in the Alentejo basin (Gulf of Cadiz) reach? Evaluating slope stability from bottom-current activities through time

2020 ◽  
Author(s):  
Davide Mencaroni ◽  
Roger Urgeles ◽  
Jonathan Ford ◽  
Jaume Llopart ◽  
Cristina Sànchez Serra ◽  
...  
Keyword(s):  
Pore Pressure ◽  
Sediment Supply ◽  
Excess Pore Pressure ◽  
Bottom Current ◽  
Gulf Of Cadiz ◽  
Strait Of Gibraltar ◽  
Gulf Of Cádiz ◽  
The Stability ◽  
Iberian Margin ◽  
Excess Pore

<p>Contourite deposits are generated by the interplay between deepwater bottom-currents, sediment supply and seafloor topography. The Gulf of Cadiz, in the Southwest Iberian margin, is a famous example of extensive contourite deposition driven by the Mediterranean Outflow Water (MOW), which exits the Strait of Gibraltar, flows northward following the coastline and distributes the sediments coming from the Guadalquivir and Guadiana rivers. The MOW and related contourite deposits affect the stability of the SW Iberian margin in several ways: on one hand it increases the sedimentation rate, favoring the development of excess pore pressure, while on the other hand, by depositing sand it allows pore water pressure to dissipate, potentially increasing the stability of the slope.</p><p>In the Gulf of Cadiz, grain size distribution of contourite deposits is influenced by the seafloor morphology, which splits the MOW in different branches, and by the alternation of glacial and interglacial periods that affected the MOW hydrodynamic regimes. Fine clay packages alternates with clean sand formations according to the capacity of transport of the bottom-current in a specific area. Generally speaking, coarser deposits are found in the areas of higher MOW flow energy, such as in the shallower part of the slope or in the area closer to the Strait of Gibraltar, while at higher water depths the sedimentation shifts to progressively finer grain sizes as the MOW gets weaker. Previous works show that at present-day the MOW flows at a maximum depth of 1400 m, while during glacial periods the bottom-current could have reached higher depths.</p><p>In this study we derived the different maximum depths at which the MOW flowed by analyzing the distribution of sands at different depths along the Alentejo basin slope, in the Northern sector of the Gulf of Cadiz.</p><p>Here we show how changes in sand distribution along slope, within the stratigraphic units deposited between the Neogene and the present day, are driven by glacial – interglacial period alternation that influenced the hydrodynamic regime of the MOW.</p><p>By deriving the depositional history of sand in the Alentejo basin, we are able to correlate directly the influence that climatic cycles had on the MOW activity. Furthermore, by interpreting new multi-channel seismic profiles we have been able to derive a detailed facies characterization of the uppermost part of the Gulf of Cadiz.</p><p>An accurate definition of sand distribution along slope plays an important role in evaluating the stability of the slope itself, e.g. to understand if the sediments may be subjected to excess pore pressure generation. As sand distribution is a direct function of the bottom-current transport capacity, the ultimate goal of this study is to understand how climate variations can affect the stability of submarine slope by depositing contourite-related sand.</p>

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