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.

Poro-Elasto-Plastic Model for Wave-Induced Liquefaction

2014 ◽  
Author(s):  
Chengcong Liao ◽  
Hongyi Zhao ◽  
Dong-Sheng Jeng
Keyword(s):  
Two Dimensional ◽  
Plastic Model ◽  
Centrifuge Tests ◽  
Pore Pressures ◽  
Proposed Model ◽  
Progressive Waves ◽  
Plastic Components ◽  
Excess Pore Pressures ◽  
Wave Induced ◽  
Pore Pressure Build Up

In this study, a two-dimensional poro-elasto-plastic model for the wave-induced liquefaction in a porous seabed was presented. 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 in marine sediments. The proposed 2D poro-elasto-plastic model allows for the pore pressure build-up process in a sandy seabed. The proposed model overall agreed well with the previous wave experiments and centrifuge tests. Numerical example shows that the pattern of progressive waves -induced liquefaction gradually changed from 2D to 1D.

Inclined Perimeter Drains Performance as Liquefaction Countermeasure Techniques Below Existing Buildings

2020 ◽  
Vol 14 (03) ◽  
pp. 2050015
Author(s):  
Samy Garcıáa-Torres ◽  
Gopal Santana Phani Madabhushi
Keyword(s):  
Pore Pressure ◽  
Structural Damage ◽  
Excess Pore Pressure ◽  
Existing Buildings ◽  
Ground Shaking ◽  
Vertical Drains ◽  
Centrifuge Tests ◽  
Pore Pressures ◽  
Excess Pore Pressures ◽  
Excess Pore

Reducing the risk of structural damage due to earthquake-induced liquefaction in new and existing buildings is a challenging problem in geotechnical engineering. Drainage countermeasure techniques against liquefaction have been studied over the last decades with an emphasis on the use of vertical drains. This technique aims to allow a rapid dissipation of excess pore pressures generated in the soil during the earthquake thereby limiting the peak excess pore pressures and consequently improve the structural response. Rapid drainage in the post-earthquake period in the presence of these drains helps quick recovery of the soil strength. Recent studies propose different variations in the vertical drains arrangement to improve the excess pore pressure redistribution in the soil around structures. However, conventional arrangements for existing buildings do not achieve an adequate proximity from the drains to the soil below the foundation. To address this, the performance of inclined and vertical perimeter drain arrangements are studied in this paper. Dynamic centrifuge tests were carried out for the different arrangements in order to evaluate the excess pore pressure generation due to ground shaking and the following dissipation together with the foundation settlement and dynamic response.

Two-Dimensional Model for Wave-Induced Pore Pressure Accumulation in Marine Sediments

2013 ◽  
Author(s):  
Hongyi Zhao ◽  
Dong-Sheng Jeng ◽  
Huijie Zhang ◽  
Jisheng Zhang
Keyword(s):  
Pore Pressure ◽  
Marine Sediments ◽  
Wave Motion ◽  
Present Model ◽  
Two Dimensional ◽  
New Model ◽  
One Dimensional ◽  
Wave Cycle ◽  
Previous Solution ◽  
Wave Induced

In this paper, a two-dimensional (2D) porous model is established to investigate the predication of the wave-induced pore pressure accumulations in marine sediments. In the new model, the VARANS equation is used as the governing equation for the wave motion, while the Biot’s consolidation theory is used for porous seabed. The present model is verified with the previous experimental data [1] and provides a better prediction of pore pressure accumulation than the previous solution [2]. With the new model, a 2D liquefied zone is formed at the beginning of the process, and then gradually move down. After a certain wave cycle (for example, 30 wave cycles in the numerical example), the liquefaction zone will become one-dimensional (1D) and continuously move down and eventually approaches to a constant. Numerical results also conclude the maximum liquefaction depth increases as wave height increases and in shallow water.

Hydraulic fracturing from induced pore pressures in clay soils

1983 ◽  
Vol 20 (3) ◽  
pp. 546-555
Author(s):  
H. B. Poorooshasb ◽  
Raymond N. Yong
Keyword(s):  
Hydraulic Fracturing ◽  
Pore Pressure ◽  
Clay Soil ◽  
Elastic Analysis ◽  
Load Step ◽  
Pressure Fields ◽  
Pore Pressures ◽  
Central Elements ◽  
Excess Pore Pressures ◽  
State Of Tension

The possibility of induced high excess pore pressures during consolidation of a clay soil with transverse drainage developing hydraulic fracturing in the soil is presented. The elastic analysis pursued herein examines the stress and pore pressure fields generated under vertical consolidation loading with drainage allowed only in the transverse direction. The results indicate that when the load step increments are too large, in comparison with previous loads, the transverse effective stress associated with the central elements of the soil being loaded can become negative. At that time, a state of tension will be created and a form of hydraulic fracturing will result. Key words: pore pressure, hydraulic fracture, elastic analysis, transverse drainage, consolidation.

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.

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.

Surpressions interstitielles développées par le fonçage dans les sols cohérents

1979 ◽  
Vol 16 (4) ◽  
pp. 814-827
Author(s):  
M. Peignaud
Keyword(s):  
Pore Pressure ◽  
Excess Pore Pressure ◽  
Overburden Pressure ◽  
Pore Pressures ◽  
Excess Pore Pressures ◽  
Plastic Clays ◽  
Excess Pore

The Laboratoire Régional des Ponts et Chaussées, Angers (France) has investigated the excess pore pressures developed during the driving of a piezometer probe at different rates on four sites. Attention is drawn to the important differences between the pore pressures measured during penetration and at rest.During driving, negative excess pore pressures are measured. When the piezometer is stopped the pore pressures become large and positive. For the soils tested, i.e., plastic to highly plastic clays, the maximum excess pore pressure at rest may be estimated from the total overburden pressure. [Journal translation]

A New Technique for Reduction of Excess Pore Pressures During Pile Driving

1974 ◽  
Vol 11 (3) ◽  
pp. 423-430 ◽  
Author(s):  
Robert D. Holtz ◽  
Per Boman
Keyword(s):  
Pore Pressure ◽  
Alternative Methods ◽  
New Technique ◽  
Excess Pore Pressure ◽  
Relative Reduction ◽  
Pile Driving ◽  
Pore Pressures ◽  
A New Technique ◽  
Excess Pore Pressures ◽  
Excess Pore

A new technique is described whereby excess pore pressures induced during pile driving in soft, varved silts and clays were economically reduced to a safe level. The technique was applied to piles at a bridge site south of Stockholm, Sweden, where a small slide had occurred during pile driving. A new paper–plastic drain was attached to the wood piles during driving, and two pulling tests indicated that the drain was undamaged under normal driving conditions. The excess pore pressure generated during the driving of some 13 test piles without drains and 48 piles with drains was measured. The data indicated at least a 50% relative reduction in excess pore pressure when the drain was used. In addition, the cost of the technique was considerably less than alternative methods for dealing with dangerous excess pore water pressures resulting from piling in similar soils. The technique has been successfully applied at two other piling sites in Sweden.

Analysis of the Pore Pressure Changes Following the Excavation of a Slope

1975 ◽  
Vol 12 (3) ◽  
pp. 429-440 ◽  
Author(s):  
Kurt D. Eigenbrod
Keyword(s):  
Pore Pressure ◽  
Field Data ◽  
Pressure Measurements ◽  
Pore Pressures ◽  
Field Evidence ◽  
Slope Excavation ◽  
Order Of Magnitude ◽  
Excess Pore Pressures ◽  
Pressure Changes ◽  
Excess Pore

In a numerical analysis the pore pressure changes due to excavation of a slope and the subsequent dissipation of excess pore pressures were calculated. The analytical results of the pore pressure changes due to unloading of a slope agree reasonably well with pore pressure measurements in comparable embankments. This suggests that pore pressures immediately after slope excavation can be predicted analytically in homogeneous materials.The results of an analysis dealing with the dissipation of excess pore pressures due to unloading can also be substantiated by field evidence; however, only few comparable field data are available. For many slopes it can be noted that the time for full dissipation is of the same order of magnitude as the time between excavation and failure. This suggests that many failures might be caused by the delayed equalization of pore pressures.

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