Experimental Study for Wave-Induced Oscillatory Pore Pressures in a Sandy Seabed

2014 ◽  
Author(s):  
Bo Liu ◽  
Dong-Sheng Jeng ◽  
Guanlin Ye
Keyword(s):  
Experimental Study ◽  
Pore Pressure ◽  
Vertical Cylinder ◽  
Soil Conditions ◽  
Soil Parameters ◽  
Pore Pressures ◽  
Sandy Deposit ◽  
Dimensional Facility ◽  
Set Up ◽  
Wave Induced

In this paper, an experimental study for wave-induced pore pressures in marine sediments was reported. In the experiment, a one-dimensional facility was set up with a vertical cylinder and a 1.8 m thick sandy deposit and 0.2 m thick water above the deposit. Unlike the previous experiments [1], additional static water pressures were added on the harmonic dynamic wave pressure and more pore pressure gauges were buried in the deposit, which allowed us to simulate the case with larger water depth and better describe the distribution of pore pressure trend. A series of experiments with 3000 cycles in each test were conducted under numerous different wave and soil conditions, which allowed us to examine the influence of wave and soil parameters on the wave-induced pore pressures as well as liquefaction. The experimental results show the significant influence of liquefaction on sandy seabed in shallow water. Furthermore, some new experimental phenomenon was observed. The depth of sandy deposit was usually considered to be unchanged in theoretical calculation, while the depth of which was indeed changed periodic with wave loading, which was observed and recorded in the experiments.

scholarly journals 3-D Poro-Elastoplastic Model for Short-Crested Wave-Induced Pore Pressures in a Porous Seabed

2015 ◽  
Vol 9 (1) ◽  
pp. 408-416 ◽  
Author(s):  
Z. S. Wong ◽  
C. C. Liao ◽  
D. S. Jeng
Keyword(s):  
Pore Pressure ◽  
Present Model ◽  
Three Dimensional ◽  
Volumetric Strain ◽  
Soil Characteristics ◽  
Elastoplastic Model ◽  
Experiment Data ◽  
Pore Pressures ◽  
Wave Induced ◽  
Plastic Volumetric Strain

In this paper, a three-dimensional poro-elastoplastic model for the short-crested wave-induced pore pressures in a porous seabed is presented. Unlike the previous models, both elasticity and plasticity of seafloor are considered in the present model. This study considers the effects of wave and soil characteristics on the pore pressures and was validated with the previous wave experiment data. As the numerical analysis shows, higher value of plastic parameter leads to a faster residual pore pressure accumulation, which is closely related to the occurrence of seabed liquefaction. In particular, at the dissipation stage, residual pore pressure sharply decreases when enlarging plastic parameter , which dominates the velocity of accumulation of plastic volumetric strain.

Poro-Elasto-Plastic Model for the Wave-Induced Liquefaction1

2015 ◽  
Vol 137 (4) ◽  
Author(s):  
C. C. Liao ◽  
H. Zhao ◽  
D.-S. Jeng
Keyword(s):  
Pore Pressure ◽  
Marine Sediments ◽  
Plastic Model ◽  
Whole Process ◽  
Centrifuge Tests ◽  
Pore Pressures ◽  
2D Pattern ◽  
Plastic Components ◽  
Excess Pore Pressures ◽  
Wave Induced

In this paper, we presented an integrated numerical model for the wave-induced pore pressures in marine sediments. Two mechanisms of the wave-induced pore pressures were considered. Both elastic components (for oscillatory) and the plastic components (for residual) were integrated to predict the wave-induced excess pore pressures and liquefaction in marine sediments. The proposed two-dimensional (2D) poro-elasto-plastic model can simulate the phenomenon of the pore pressure buildup and dissipation process in a sandy seabed. The proposed model overall agreed well with the previous wave experiments and geo-centrifuge tests. Based on the parametric study, first, we examined the effects of soil and wave characteristics on the pore pressure accumulations and residual liquefaction. Then, a set of analysis on liquefaction potential was presented to show the development of liquefaction zone. Numerical example shows that the pattern of progressive waves-induced liquefaction gradually changes from 2D to one-dimensional (1D), while the standing wave-induced liquefaction stays in a 2D pattern in the whole process.

Analysis of flexible drains in Changi reclamation

1989 ◽  
Vol 26 (3) ◽  
pp. 401-417 ◽  
Author(s):  
G. P. Karunaratne ◽  
S. A. Tan ◽  
S. L. Lee ◽  
V. Choa
Keyword(s):  
Hydraulic Conductivity ◽  
Pore Pressure ◽  
Soft Clay ◽  
Test Site ◽  
Soil Parameters ◽  
Vertical Drains ◽  
The Real ◽  
Pore Pressures ◽  
Vertical Hydraulic Conductivity ◽  
Layered Clay

Vertical drains and surcharge were used to accelerate the consolidation of soft marine clay under the second runway at the Changi Airport site. To study this problem further, the consolidation of a strip of layered clay deposit under a large reclamation is analysed as a two-dimensional problem in accordance with Biot's theory using the finite difference method. The soil with vertical drains is replaced with an equivalent soil having an enhanced vertical hydraulic conductivity obtained by equating the surface settlement of the real soil with that of the equivalent soil. The soil modulus and the hydraulic conductivity of the real soil are varied with the prevailing effective stress in the soil. The operating soil parameters determined by back analysing the field observations in a pilot test were then utilized to predict the behaviour of the main works. Soil displacement at any point in the plane of strain could be determined within a reasonable accuracy. As the equivalent soil is obtained by equating the average degree of consolidation, pore pressures cannot be predicted accurately within the drain area. However, the trend of pore pressure variation across the test site is implied by the analysis. The trend showed that pore pressures outside the drain area are found to influence the settlement and pore pressure inside the drain area, causing retardation in the consolidation of the drain area. Key words: Biot's analysis, consolidation, flexible drains, numerical analysis, soft clay.

scholarly journals Experimental Study for Wave-Induced Pore-Water Pressures in a Porous Seabed around a Mono-Pile

2019 ◽  
Vol 7 (7) ◽  
pp. 237 ◽  
Author(s):  
Shaohua Wang ◽  
Pandi Wang ◽  
Hualing Zhai ◽  
Qibo Zhang ◽  
Linya Chen ◽  
...  
Keyword(s):  
Experimental Study ◽  
Spatial Distribution ◽  
Pore Pressure ◽  
Pore Water ◽  
Wave Height ◽  
Experimental Results ◽  
Period Increase ◽  
Pore Water Pressures ◽  
Series Of Experiments ◽  
Wave Induced

In this paper, the results of a series of experiments on wave-induced pore-water pressures around a mono-pile are presented. Unlike the previous study, in which the mono-pile was fully buried, the mono-pile in this study was installed at 0.6 m below the seabed surface. In this study, we focus on the pore-water pressures around the mono-pile and beneath the pile. The experimental results lead to the following conclusions: (1) the seabed response is more pronounced near the surface (in the region above 30 cm deep), and the rate of pore pressure attenuation gradually slows down. For the region below 0.3 m, the response is much smaller; (2) in general, along the surface of the pile, pore pressures increase as the wave height and wave period increase; (3) the spatial distribution of pore pressure near the pile will vary with different wave periods, while the wave height only has a significant effect on the amplitude; and (4) At z = −0.15 m, the pore pressure in front of the pile is the largest, while at the point 0.1 m below the bottom of the pile, the largest pore pressure occurs behind the pile.

scholarly journals Breaking-Wave Induced Transient Pore Pressure in a Sandy Seabed: Flume Modeling and Observations

2021 ◽  
Vol 9 (2) ◽  
pp. 160
Author(s):  
Changfei Li ◽  
Fuping Gao ◽  
Lijing Yang
Keyword(s):  
Pore Pressure ◽  
Wave Height ◽  
Wave Breaking ◽  
Breaking Waves ◽  
Breaking Wave ◽  
Regular Waves ◽  
Large Wave ◽  
Pore Pressures ◽  
Linear Waves ◽  
Wave Induced

Previous studies on wave-induced pore pressure in a porous seabed mainly focused on non-breaking regular waves, e.g., Airy linear waves or Stokes non-linear waves. In this study, breaking-wave induced pore pressure response in a sandy seabed was physically simulated with a large wave flume. The breaking-wave was generated by superimposing a series of longer waves onto the foregoing shorter waves at a specified location. Water surface elevations and the corresponding pore pressure in the process of wave breaking were measured simultaneously at three typical locations, i.e., at the rear, just at, and in front of the wave breaking location. Based on test results, characterization parameters are proposed for the wave surface elevations and the corresponding pore-pressures. Flume observations indicate that the wave height was greatly diminished during wave breaking, which further affected the pore-pressure responses. Moreover, the measured values of the characteristic time parameters for the breaking-wave induced pore-pressure are larger than those for the free surface elevation of breaking-waves. Under the action of incipient-breaking or broken waves, the measured values of the amplitude of transient pore-pressures are generally smaller than the predicted results with the analytical solution by Yamamoto et al. (1978) for non-breaking regular waves with equivalent values of characteristic wave height and wave period.

THE PORE PRESSURE – STRAIN RELATIONSHIP OF NORMALLY CONSOLIDATED UNDISTURBED CLAYS: PART I. THEORETICAL CONSIDERATIONS

1969 ◽  
Vol 6 (4) ◽  
pp. 383-394 ◽  
Author(s):  
K. Y. Lo
Keyword(s):  
Pore Pressure ◽  
Critical Review ◽  
Principal Strain ◽  
Pore Pressures ◽  
Strain Relationship ◽  
Set Up ◽  
Relationship Of ◽  
Theoretical Considerations

This paper presents a critical review of the current theories of predicting pore pressures in saturated clays. These theories are generalized and examined and their limitations discussed. It is shown mathematically that the pore pressure induced by shear may be expressed as a sole function of major principal strain, and this approach eliminates the anomalies inherent in the "stress theories" for pore pressure. A hypothesis is also developed to provide a possible mechanism of pore pressure set up in undisturbed normally-consolidated clays.

scholarly journals Effective stresses in a porous seabed of finite thickness: inertia effects

2000 ◽  
Vol 37 (6) ◽  
pp. 1383-1392 ◽  
Author(s):  
D S Jeng ◽  
M S Rahman
Keyword(s):  
Pore Pressure ◽  
Finite Thickness ◽  
Relative Difference ◽  
Inertia Force ◽  
Soil Conditions ◽  
Inertia Effects ◽  
Effective Stresses ◽  
Present Solution ◽  
Wave Induced ◽  
Inertia Forces

The evaluation of wave-induced pore pressure and effective stresses is an important factor in the design of offshore installations. However, to simplify a complicated problem, most previous investigations have ignored the effects of inertia forces. This paper presents a new semi-analytical solution to the equations governing the wave-induced seabed response, including inertia terms for the whole problem. The numerical results show that the inertia forces cannot always be ignored. The relative difference between the present solution (with inertia items) and the previous solution (without inertia items) may reach 17% of po under certain combinations of wave and soil conditions. Key words: inertia force, pore pressure, effective stresses.

Experimental study of the effect of wind above irregular waves on the wave-induced load statistics

2021 ◽  
pp. 103940
Author(s):  
Julie Caroee Kristoffersen ◽  
Henrik Bredmose ◽  
Christos Thomas Georgakis ◽  
Hubert Branger ◽  
Christopher Luneau
Keyword(s):  
Experimental Study ◽  
Irregular Waves ◽  
Wave Induced
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