Pore Water Pressure Response of Fully Saturated Soil Beds during Earthquake–Tsunami Multi‐Hazards

2019 ◽  
Vol 109 (5) ◽  
pp. 1785-1796 ◽  
Author(s):  
Yingqing Qiu ◽  
Henry Benjamin Mason
Keyword(s):  
Numerical Model ◽  
Pore Water ◽  
Numerical Experiments ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Coastal Areas ◽  
Soil Liquefaction ◽  
Beach Sand ◽  
Liquefaction Potential ◽  
Quiescent Period

Abstract Soil liquefaction causes significant damage to coastal infrastructure and buildings worldwide. Strong earthquake shaking can cause soil liquefaction in fully saturated sand deposits. Also, tsunamis can induce liquefaction, as well as enhanced sediment transport and scour, in coastal areas. To understand soil liquefaction potential during an earthquake–tsunami multi‐hazard, we develop a numerical model to predict the multi‐hazard induced excess pore water pressures. We calibrate and verify the numerical model by comparing results with laboratory experiments. Then, we perform numerical experiments using a recorded earthquake motion and hypothetical tsunami wave heights. The numerical experiments show that beach sand liquefies during earthquake loading. The sand then resediments during the quiescent period and the tsunami runup stage. Finally, during rapid tsunami drawdown, liquefaction can occur again, and liquefaction potential during tsunami drawdown primarily depends on the soil’s hydraulic conductivity, as well as the duration of the quiescent period. The results emphasize the need for predictions of earthquake–tsunami loading, as well as measurements of soil properties in coastal areas.

Prediction of liquefaction potential and pore water pressure beneath machine foundations

2014 ◽  
Vol 4 (3) ◽  
Author(s):  
Mohammed Fattah ◽  
Mohammed Al-Neami ◽  
Nora Jajjawi
Keyword(s):  
Pore Water ◽  
Sandy Soil ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Soil Liquefaction ◽  
Elastic Model ◽  
Liquefaction Resistance ◽  
Overburden Pressure ◽  
Liquefaction Potential ◽  
Frequency Changes

AbstractThe present research is concerned with predicting liquefaction potential and pore water pressure under the dynamic loading on fully saturated sandy soil using the finite element method by QUAKE/W computer program. As a case study, machine foundations on fully saturated sandy soil in different cases of soil densification (loose, medium and dense sand) are analyzed. Harmonic loading is used in a parametric study to investigate the effect of several parameters including: the amplitude frequency of the dynamic load. The equivalent linear elastic model is adopted to model the soil behaviour and eight node isoparametric elements are used to model the soil. Emphasis was made on zones at which liquefaction takes place, the pore water pressure and vertical displacements develop during liquefaction. The results showed that liquefaction and deformation develop fast with the increase of loading amplitude and frequency. Liquefaction zones increase with the increase of load frequency and amplitude. Tracing the propagation of liquefaction zones, one can notice that, liquefaction occurs first near the loading end and then develops faraway. The soil overburden pressure affects the soil liquefaction resistance at large depths. The liquefaction resistance and time for initial liquefaction increase with increasing depths. When the frequency changes from 5 to 10 rad/sec. (approximately from static to dynamic), the response in displacement and pore water pressure is very pronounced. This can be attributed to inertia effects. Further increase of frequency leads to smaller effect on displacement and pore water pressure. When the frequency is low; 5, 10 and 25 rad/sec., the oscillation of the displacement ends within the period of load application 60 sec., while when ω = 50 rad/sec., oscillation continues after this period.

scholarly journals Soil liquefaction as an identification test

2019 ◽  
Vol 92 ◽  
pp. 08008
Author(s):  
Bozana Bacic ◽  
Ivo Herle
Keyword(s):  
Pore Water ◽  
Laboratory Testing ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Initial Density ◽  
Soil Liquefaction ◽  
Triaxial Tests ◽  
Cyclic Triaxial ◽  
Cyclic Triaxial Tests ◽  
Identification Test

Time-consuming and complicated investigations of soil liquefaction in cyclic triaxial tests are the most common way of laboratory analysis of this phenomenon. Moreover, the necessary equipment for the performance of cyclic triaxial tests is very expensive. Much simpler method for laboratory testing of the soil liquefaction has been developed at the Institute of Geotechnical Engineering at the TU Dresden. This method takes into account the pore water pressure build-up during cyclic shearing within a short time period. During the test, the soil sample is subjected to horizontal cyclic loading and the generated pore water pressure is measured. In the first series of these experiments, a dependence of the pore water pressure buildup on the initial density of soil could be observed, as expected. When comparing different soils, it is shown that the tendency to liquefaction depends also on the granulometric properties (e.g. grain size distribution) of the soil. The aim of the further development is to establish a simple identification test for laboratory testing of the soil liquefaction.

Influences on Liquefaction-Induced Damage of Pore Water Seepage into an Unsaturated Surface Layer

2020 ◽  
Vol 15 (6) ◽  
pp. 754-764
Author(s):  
Yohsuke Kawamata ◽  
Hiroshi Nakazawa ◽  
◽  
Keyword(s):  
Surface Layer ◽  
Pore Water ◽  
Groundwater Level ◽  
Water Movement ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Lateral Spreading ◽  
Soil Liquefaction ◽  
Water Seepage ◽  
Long Duration

Various studies have examined soil liquefaction and the resultant structure damage. The 1995 Southern Hyogo Prefecture Earthquake, a near-field earthquake, caused significant damage when the ground was liquified due to the rapidly increased pore water pressure in several cycles of major motions. Therefore, the effect of pore water movement during earthquakes has been assumed to be limited, and liquefaction has mainly been evaluated in undrained conditions. Additionally, the ground and building settlement or inclination caused by liquefaction are deemed to result from pore water drainage after earthquakes. Meanwhile, in the 2011 Tohoku Earthquake, off the Pacific Coast, a subduction-zone earthquake, long-duration motions were observed for over 300 s with frequent aftershocks. Long-duration motions with frequent aftershocks are also anticipated in a future Nankai Trough Earthquake. The effect of pore water movement not only after but during an earthquake should be considered in cases where pore water pressure gradually increases in long-duration motion. The movement of pore water during and after an earthquake typically results in simultaneous dissipation and buildup of water pressure, as well as volumetric changes associated with settlement and lateral spreading. Such effects must reasonably be considered in liquefaction evaluation and building damage prediction. This research focuses on pore water seepage into the unsaturated surface layer caused by the movement of pore water. Seepage experiments were performed based on parameters such as height of test ground, ground surface permeability, and liquefaction duration. In the tests, water pressure when the saturated ground below the groundwater level is fully liquified was applied to the bottom of the specimen representing an unsaturated surface layer. Seepage behaviors into the unsaturated surface layer were then evaluated based on the experiment data. The results show that the water level rises due to pore water seepage from the liquefied ground into the unsaturated surface layer right above the liquefied ground. For this reason, a ground shallower than the original groundwater level can be liquified.

Earthquake-induced deformation analyses of the Upper San Fernando Dam under the 1971 San Fernando Earthquake

2001 ◽  
Vol 38 (1) ◽  
pp. 1-15 ◽  
Author(s):  
Guoxi Wu
Keyword(s):  
Finite Element ◽  
Pore Water ◽  
Effective Stress ◽  
Pore Water Pressure ◽  
Ground Deformation ◽  
Water Pressure ◽  
Soil Liquefaction ◽  
Shear Stresses ◽  
Cyclic Shear ◽  
San Fernando

A nonlinear effective stress finite element approach for dynamic analysis of soil structure is described in the paper. Major features of this approach include the use of a third parameter in the two-parameter hyperbolic stress-strain model, a modified expression for unloading–reloading modulus in the Martin–Finn–Seed pore-water pressure model, and an additional pore-water pressure model based on cyclic shear stress. The additional pore-water pressure model uses the equivalent number of uniform cyclic shear stresses for the assessment of pore-water pressure. Dynamic analyses were then conducted to simulate the seismically induced soil liquefaction and ground deformation of the Upper San Fernando Dam under the 1971 San Fernando Earthquake. The analyses were conducted using the finite element computer program VERSAT. The computed zones of liquefaction and deformation are compared with the measured response and with results obtained by others.Key words: effective stress method, finite element analysis, Upper San Fernando Dam, earthquake deformation, VERSAT.

Soil Liquefaction Assessment by Anisotropic Cyclic Triaxial Test

2018 ◽  
pp. 631-664
Author(s):  
Koray Ulamis
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Axial Strain ◽  
Water Pressure ◽  
Sandy Soils ◽  
Soil Liquefaction ◽  
Cyclic Triaxial ◽  
Loading Case ◽  
Anisotropic Consolidation ◽  
Assessment Standard

Liquefaction of saturated sandy soils is one of the most significant aspects of earthquake triggered natural hazards. The main mechanism deals with the loss of effective stress due to rapid pore water pressure generation during earthquake shaking. This chapter involves with the fundamental mechanism and impacts of liquefaction. Liquefaction susceptibility of geological environments are briefly represented for preliminary assessment. Standard procedures of liquefaction are summarized. The dynamic response of sands are also reviewed. A case of anisotropic loading is considered, using three different particle sized sands below a shallow footing. Such sandy soils are subjected to anisotropic consolidation before performing undrained cyclic triaxial testing along limited cycles. Variation of axial strain, pore water pressure and related parameters are investigated. Main outcome of this study is to review the initial liquefaction state of sands by anisotropic loading case.

Influence of Soil Saturation on the Free Field Response of Liquefiable Soils

2011 ◽  
Vol 378-379 ◽  
pp. 237-240
Author(s):  
Fu Sheng Liu ◽  
Han Bing Bian
Keyword(s):  
Cyclic Loading ◽  
Numerical Model ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Free Field ◽  
Soil Liquefaction ◽  
Finite Element Program ◽  
Partially Saturated ◽  
Field Response ◽  
Soil Saturation

Free field response of partially saturated sands to cyclic loading, with a particular attention to soil liquefaction has been studied. The study has been conducted using a numerical model elaborated for the liquefaction of partially saturated soils together with a cyclic elastoplastic constitutive relation implemented in a finite element program. The numerical model and the analysis of the influence of soil saturation on the free field response, for different positions of the water table have been investigated respectively. The result shows that the soil saturation degree largely affects the free field response to cyclic loading, with a decrease in soil saturation leading to a decrease in the rate of generation of excess pore-water pressure, and consequently to a reduction in the liquefaction risk.

scholarly journals Analysis of liquefaction risk of sterile material in the inner dump of North Pesteana quarry in the conditions of flooding of the remaining gap

2020 ◽  
Vol 305 ◽  
pp. 00005
Author(s):  
Izabela Maria Apostu ◽  
Maria Lazar ◽  
Florin Faur
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Significant Risk ◽  
Saturated Sand ◽  
Geological Process ◽  
Liquefaction Potential ◽  
The North ◽  
Liquefaction Process ◽  
Potential Area

In the conditions of the dump slopes formed by loose rocks, predominantly sandy rocks, which are at the first saturation, there is a significant risk of sliding due to liquefaction of the waste material. The liquefaction process may be triggered by hydrological, mechanical or seismic factors. In saturated sand, the space between the solid granules is completely filled with water, and the pore water pressure, which increases as the depth increases, causes the grains to move away from each other, so the material is flowing. Among the methods for assessing the liquefaction potential of rock masses/deposits can be summarized: historical phenomena observations, studying the liquefying potential area maps, analysis of geological process that led to the creation of rock deposits and the nature of rocks. The paper aims at assessing the risk of liquefaction of sterile material in the inner dump of the North Pesteana quarry during the flooding of the remaining gap, since the preliminary studies found that the sterile material consists of important fractions of sand, indicating that there is liquefaction potential. The risk of liquefaction was determined taking into account the liquefaction potential, the nature of the objectives in the area and the probability of liquefaction.

Pore-Water Pressure Changes during Soil Liquefaction

1976 ◽  
Vol 102 (4) ◽  
pp. 323-346 ◽  
Author(s):  
H. Bolton Seed ◽  
Philippe P. Martin ◽  
John Lysmer
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Soil Liquefaction ◽  
Pressure Changes

scholarly journals Performance Assessment of Composite Skirted Ground Reinforcement System in Liquefiable Ground Under Repeated Dynamic Loading Conditions

2021 ◽  
Author(s):  
Vijay Kumar S P ◽  
Ganesh Kumar Shanmugam ◽  
Saurabh Dutta Gupta
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Ground Motions ◽  
Water Pressure ◽  
Soil Liquefaction ◽  
Stone Columns ◽  
Loading Conditions ◽  
Reinforcement System ◽  
Soil Densification ◽  
Composite Reinforcement

Abstract Occurrence of earthquake generates both horizontal and vertical ground motions. In saturated sands, combination of generated ground motions and pore water pressures induces soil liquefaction. In this study, a composite skirted ground reinforcement system was developed to mitigate generation of pore water pressure in liquefiable soils and also to attenuate incoming ground motions to the foundation. The composite system contains Poly Urethane foam as an isolation barrier for ground motion attenuation with stone columns for improving both soil densification and drainage. The performance of this composite reinforcement system was evaluated under repeated acceleration loading conditions to estimate its efficiency. For testing, saturated ground model having 40% and 60% relative density was prepared and investigated with and without the composite reinforcement system. Test results showed that, the developed skirted ground reinforcement system effectively mitigates the interaction of incoming ground motions with the foundation and also improves the re-liquefaction resistance of soil compared to that of unreinforced ground.

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