scholarly journals Validation and Verification of Semi-Empirical Methods for Evaluating Liquefaction Using Finite Element Method

2018 ◽  
Vol 149 ◽  
pp. 02028 ◽  
Author(s):  
Soukaina Touijrate ◽  
Khadija Baba ◽  
Mohamed Ahatri ◽  
Lahcen Bahi
Keyword(s):  
Finite Element ◽  
High Speed ◽  
Water Pressure ◽  
Soil Liquefaction ◽  
Empirical Methods ◽  
Liquefaction Potential ◽  
North West ◽  
Cone Penetration Tests ◽  
The North ◽  
Semi Empirical

Liquefaction is a hazardous and temporary phenomenon by which a soil saturated with water loses some or all of its resistance. The undrained conditions and a cyclic load increase the pores water pressure inside the soil and therefore a reduction of the effective stress. Nowadays many semi-empirical methods are used to introduce a proposition to evaluate the liquefaction's potential using the in-situ test results. The objective of this paper is to study their ability to correctly predict the liquefaction potential by modelling our case using finite element methods. The study is based on the data of Cone Penetration Tests experimental results of the Casablanca-Tangier High-Speed Line exactly between PK 116 + 450 and PK 116 + 950 and near of Moulay-Bousselham city. It belongs to the Drader-Soueir basin region which is located in the North-West of Morocco. This region had a specific soil’s formation, the first 50 meters are characterised by the existence of sand layers alternating with layers of clay. These formations are very loose and saturated which suggests the possibility of soil liquefaction. We present and discuss the results of applying the Olsen method [1], the Juang method [2] and the Robertson method [3], in the evaluation of liquefaction susceptibility. Apart from the previous empirical analysis to evaluate the liquefaction potential, numerical modelling is performed in this study.

scholarly journals Semi-Empirical Method for evaluating Risk of Liquefaction during earthquakes a Study Case of Rhiss Dam

2020 ◽  
Vol 150 ◽  
pp. 01004
Author(s):  
Fatima Ezzahraa Latifi ◽  
Khadija Baba ◽  
Lahcen Bahi ◽  
Soukaina Touijrate ◽  
Choukri Cherradi
Keyword(s):  
Water Pressure ◽  
Empirical Method ◽  
Soil Liquefaction ◽  
The North ◽  
Fine Soil ◽  
Load Increase ◽  
Al Hoceima ◽  
Stability Of Structures ◽  
Water Saturated ◽  
Semi Empirical

Liquefaction is a hazardous and temporary phenomenon by which water saturated soil loses some or all of its resistance. The undrained conditions linked to the cyclic load increase the pores water pressure inside the soil and consequently reduce effective stress. As a result, the soil can no longer resist or hold the shear forces, and lead to enormous deformations that directly influence the stability of structures and infrastructures foundations. Since 1964, several semi-empirical methods have been invented to evaluate the liquefaction potential using the in-situ test results. This study is based on the correlation between experimental data results of Menard pressuremeter and SPT dynamic penetrometer tests. Samples used in this test come from the Rhiss dam located in the North of Morocco, 24 kilometers as the crow flies from the town of Al Hoceima and south of the foundations of a calcareous ridge. The studied area have high seismic activity and a high percentage of fine soil elements, which suggests the possibility of soil liquefaction. We present and discuss the results of applying Idriss and Boulanger, and Youd et al methods in the evaluation of liquefaction susceptibility.

scholarly journals A Numerical Study on Liquefaction Induced Settlements by Using PM4Sand Model

2021 ◽  
Vol 1203 (3) ◽  
pp. 032029
Author(s):  
Ozan Subasi ◽  
Serdar Koltuk ◽  
Merve Akbas ◽  
Recep Iyisan
Keyword(s):  
Finite Element ◽  
Ground Motion ◽  
Strong Ground Motion ◽  
Water Pressure ◽  
Free Field ◽  
Sudden Increase ◽  
Empirical Methods ◽  
Soil Layers ◽  
Semi Empirical ◽  
Strong Ground

Abstract Abstract: The destructive effects of earthquakes negatively affect many people's lives and cause a large number of lives and property losses. One of the most crucial factors that increase the destructive effects and structural damages of earthquakes is the deformations in the soil layers during strong ground motion. Especially liquefaction due to sudden increase in pore water pressure during strong ground motion in saturated sandy soils causes large deformations in the soil layers; hence leads to severe damage to the structures. Therefore, it is necessary to determine the liquefaction-induced deformations and settlements in the soil layers with high liquefaction potential. Following this purpose, three different two-dimensional fully saturated soil profiles with 35, 55, 75 % relative densities were created and carried out by using different strong ground motions for estimation of liquefaction-induced free field settlements. The finite element code "Plaxis 2D" and constitutive model "PM4Sand" were used in the analysis. The results of finite element (FE) analyses were compared with semi-empirical methods in the literature. The liquefaction state observed with pore pressure ratio (Ru) and safety factor (FS) is similar in numerical and empirical methods. The FE analyses have shown that the evaluation of free-field, liquefaction-induced settlements obtained from PM4Sand-Model have considerably lower settlement values than the semi-empirical methods. However, the semi-empirical method suggested by Cetin et al. (2009) and numerical analyses gave quite similar settlement results to each other. Moreover, there is no direct relationship between the liquefaction-induced settlements and the earthquake source properties in the numerical method. However, this is different for semi-empirical methods, and there is a relationship between strong ground motion features and liquefaction-induced settlements.

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.

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.

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.

scholarly journals EVALUATING LIQUEFACTION POTENTIAL OF PUMICEOUS DEPOSITS THROUGH FIELD TESTING: CASE STUDY OF THE 1987 EDGECUMBE EARTHQUAKE

2020 ◽  
Vol 53 (2) ◽  
pp. 101-110
Author(s):  
Rolando Orense ◽  
Mohammad Asadi ◽  
Mark Stringer ◽  
Michael Pender
Keyword(s):  
Field Tests ◽  
Field Testing ◽  
Soil Liquefaction ◽  
Clear Understanding ◽  
Undisturbed Soil ◽  
Liquefaction Potential ◽  
Volcanic Origin ◽  
The North ◽  
Cyclic Resistance ◽  
Testing Case

Pumice materials, which are problematic from an engineering viewpoint, are widespread in the central part of the North Island. Considering the impacts of the 2010-2011 Christchurch earthquakes, a clear understanding of their properties under earthquake loading is necessary. For example, the 1987 Edgecumbe earthquake showed evidence of localised liquefaction of sands of volcanic origin. To elucidate on this, research was undertaken to investigate whether existing empirical field-based methods to evaluate the liquefaction potential of sands, which were originally developed for hard-grained soils, are applicable to crushable pumice-rich deposits. For this purpose, two sites, one in Whakatane and another in Edgecumbe, were selected where the occurrence of liquefaction was reported following the Edgecumbe earthquake. Manifestations of soil liquefaction, such as sand boils and ejected materials, have been reported at both sites. Field tests, including cone penetration tests (CPT), shear-wave velocity profiling, and screw driving sounding (SDS) tests were performed at the sites. Then, considering estimated peak ground accelerations (PGAs) at the sites based on recorded motions and possible range of ground water table locations, liquefaction analysis was conducted at the sites using available empirical approaches. To clarify the results of the analysis, undisturbed soil samples were obtained at both sites to investigate the laboratory-derived cyclic resistance ratios and to compare with the field-estimated values. Research results clearly showed that these pumice-rich soils do not fit existing liquefaction assessment frameworks and alternate methods are necessary to characterise them.

Cyclic Response and Instability Analysis of Seabed With Cohesionless Soils Due to Surging Waves

2021 ◽  
Author(s):  
Amin Rafiei ◽  
M. A. Gabr ◽  
M. S. Rahman ◽  
Majid Ghayoomi
Keyword(s):  
Finite Element ◽  
Pore Pressure ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Triaxial Compression ◽  
Soil Liquefaction ◽  
Cyclic Behavior ◽  
Cohesionless Soil ◽  
Compression Tests ◽  
Element Analysis

Abstract Surface waves may generate significant loadings on the seabed destabilizing sediments and the supporting marine structures. This threat is more pronounced in shallower water depths where the cyclic wave loading may induce residual pore water pressure in sediments triggering soil liquefaction. In this paper, a coupled numerical framework is presented to evaluate the interaction of waves and horizontal seabed considering nonlinear cyclic behavior of the cohesionless soil. A simple experimental model is employed for concurrent simulation of nonlinear buildup of pore pressure and deformation of saturated sand subjected to the cyclic loadings. The model (in elemental scale) is incorporated into a finite element code to solve the interaction of wave and seabed. Poro-elastoplastic response of the seabed is obtained by modifying the Biot’s coupled flow-and-deformation equations by adding equivalent nodal force terms associated with residual deformations of the soil. Potential flow theory is adopted for the fluid domain to model wave-induced pressure and flow fields. The governing equations and boundary conditions are solved using finite element analysis in time domain. The numerical framework is verified against results of cyclic triaxial compression tests and analytical solutions. Parametric studies are conducted to evaluate the effects of wave characteristics on triggering the residual liquefaction. The numerical results indicate good agreements with experimental measures. The results also show that for large waves, the progressive buildup of pore pressure in sediments may become high enough, leading to residual liquefaction. The details of the numerical model and the potential of residual liquefaction within the seabed soil are discussed.

Late Jurassic-Early Cretaceous sandstones of Algan formation: composition, genesis, sources (North-West of Koryak Highland)

2020 ◽  
pp. 48-58
Author(s):  
M. U. Gushchina ◽  
A. V. Moiseev ◽  
M. I. Tuchkova
Keyword(s):  
Early Cretaceous ◽  
High Speed ◽  
Late Jurassic ◽  
Small Distance ◽  
Marine Environments ◽  
North West ◽  
The North ◽  
Medium Speed ◽  
Mineralogical Compositions

The article presents the results of studying the petrographic and mineralogical compositions of the sandstones of the Algan formation. Sandstones represented by pelitic-fine-medium-grained quartz-feldspar lithic arenites. Two tectonically combined sandstones lithotypes found. Lithotypes were formed in two heterochronous basins by high-speed and medium-speed turbidity flows, in moderately deep marine environments, in a relatively small distance from the coast. Sedimentation was near the deltas and prodeltas. The sources of these basins were different, related to the heterochronous volcanic areas in the north of the researched region.

scholarly journals ATMOSPHERIC DISTURBANCES IN THE AIRFLOW AROUND MOUNTAINS AND THE PROBLEM OF FLIGHT SAFETY IN THE MOUNTAINS OF THE REPUBLIC OF ADYGEYA

2017 ◽  
Vol 14 ◽  
pp. 136-142
Author(s):  
Murat K. Bedanokov ◽  
Roza B. Berzegova ◽  
Saida K. Kuizheva
Keyword(s):  
High Speed ◽  
Windward Side ◽  
Maximum Height ◽  
Flight Safety ◽  
S Wave ◽  
North West ◽  
The North ◽  
Wave Disturbances ◽  
Calculation Results ◽  
The Republic

This article considers airflow around mountain systems as a meso-scale atmospheric phenomenon. It presents a non-linear stationary dimensional theoretical model of the airflow of the North-West Caucasus Mountains, taking into account characteristics of a real mountain terrain. The article further discusses the results of the calculations of the speed field of the airflow and general regularities of the origin and the scale of the rotary-wave deformation of the airflow over the mountains. The calculation results have shown that for the model scenario I at wind speed U=15 m/s the disturbances are the most intense over the ridge crests, where they are characterized by the zone with rotors. The total length of the rotor zone downwind is more than the length of its nucleus and is close enough in value to the extent of the lee part of the terrain (downwind from the main top). The area of maximum amplitudes is located in the windward side of the rotor zone. These amplitudes are several times higher than the maximum height of the mountains. For the model scenario II (U=19 m/s) wave disturbances slightly increased in length downwind, but minimally changed in amplitude. The rotary zone changed and moved downstream. The model scenario III (U=22 m/s) is accompanied by sharp transformation of the rotor zone. Closed vortices disappear; there is no purely vertical and backward motion. The flow over the mountain greatly smoothed, and the rotor area completely disappeared. Flight safety indicators over the mountains of the Republic of Adygeya for two types of aircrafts (light-engine and speed) were calculated on the basis of the obtained data. In certain conditions, flights for both high-speed and single-engine aircrafts can be considered dangerous

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