scholarly journals The Use of Ground Motion Parameters to identify the Liquefaction during a Strong Earthquake in Northern Thailand

2021 ◽  
Vol 27 (1) ◽  
pp. 1-8
Author(s):  
Lindung Zalbuin Mase
Keyword(s):  
Pore Pressure ◽  
Amplification Factor ◽  
Pressure Ratio ◽  
Excess Pore Pressure ◽  
Response Analysis ◽  
Ground Response ◽  
Ground Response Analysis ◽  
Northern Thailand ◽  
Motion Parameters ◽  
Excess Pore

This paper presents a ground response analysis to simulate the liquefaction phenomenon during the 2011 Tarlay Earthquake in northern Thailand. The site investigation data and geophysical measurements on 7 sites in northern Thailand were collected. The multi-springs element model was implemented in finite element ground response analysis. Several parameters, such as peak ground acceleration, peak ground velocity, amplification factor, excess pore pressure ratio, were observed. Furthermore, the correlation from the ground motion parameters was generated to estimate liquefaction potential, which was represented by excess pore pressure ratio. The result showed that the excess pore pressure ratio was relatively well correlated with several ground parameters, such as amplification factor, velocity-acceleration ratio, and factor of safety against liquefaction. The results could be also used for the engineering practice in predicting liquefaction potential in Northern Thailand.

Investigation of the Performance of Simplified Constitutive Models in Nonlinear 1D Effective Stress Ground Response Analysis

2021 ◽  
Author(s):  
Caroline Bessette ◽  
Samuel Yniesta
Keyword(s):  
Pore Pressure ◽  
Ground Motion ◽  
Effective Stress ◽  
Spectral Response ◽  
Constitutive Models ◽  
Excess Pore Pressure ◽  
Response Analysis ◽  
Total Stress ◽  
Ground Response ◽  
Ground Response Analysis

ABSTRACT Several building codes, such as the National Building Code of Canada, recommend that an effective stress ground response analysis be performed if a liquefiable stratum is identified within a soil profile. Although, constitutive models for total stress ground response analysis have been well verified against earthquake recordings, existing models for effective stress ground response analysis have yet to be thoroughly validated. This article investigates the predictions of five pore pressure models derived for effective stress ground response analysis. First, a dataset of five downhole arrays and two centrifuge experiments in which a potential of liquefaction was identified is presented. The profiles and ground-motion recordings are selected to represent a broad range of soil properties, ground-motion intensities, and excess-pore pressure generation levels. The differences between predictions of the effective stress models against commonly used 1D ground response total stress equivalent-linear and nonlinear analyses are evaluated. The predicted and measured motions are compared in terms of spectral response and amplification factor. The pore pressure response of all models is evaluated as a function of shear strain and found to agree well with published correlations representing the expected behavior of liquefiable soils. Although, the models show the ability to capture liquefaction triggering, the results indicate that for the selected dataset, total stress simulations were found to be, at least, as precise and accurate as the effective stress simulations. Therefore, simplified models for effective stress ground analysis should be used with caution by practicing engineers to predict surface spectra but can be used confidently to assess the potential for liquefaction triggering.

scholarly journals A semi-empirical model to predict excess pore pressure generation in partially saturated sand

2020 ◽  
Vol 195 ◽  
pp. 02026
Author(s):  
Mousavi Sayedmasoud ◽  
Majid Ghayoomi
Keyword(s):  
Pore Pressure ◽  
Empirical Model ◽  
Pressure Ratio ◽  
Pore Fluid ◽  
Excess Pore Pressure ◽  
Saturated Soils ◽  
Partial Saturation ◽  
Liquefaction Resistance ◽  
Semi Empirical ◽  
Excess Pore

Past studies revealed that excess pore pressure generation due to cyclic loading is highly governed by induced strains, volumetric deformation potential of soil, number of cycles, and bulk stiffness of pore fluid. It is well established that partial saturation can significantly reduce bulk stiffness of pore fluid and consequently excess pore pressure generation during seismic loading. On the basis of that, a number of researchers have investigated induced partial saturation as an effective soil improvement technique to increase the liquefaction resistance of fully saturated soils. This paper focuses on development of a semi- empirical model to interpret the effects of partial saturation on the excess pore pressure generation in sands. In this regard, an existing strain based excess pore pressure ratio (ru) prediction model originally developed for fully saturated soils was modified to incorporate the effect of partial saturation on the excess pore pressure generation. The literature data as well as data from a series of strain-controlled direct simple shear test were used to evaluate the reliability of the proposed equation in predicting the excess pore pressure ratio in partial saturation condition.

Liquefaction potential of silts from CPTu

2007 ◽  
Vol 44 (1) ◽  
pp. 1-19 ◽  
Author(s):  
Dawn A Shuttle ◽  
John Cunning
Keyword(s):  
Finite Element ◽  
Pore Pressure ◽  
Earthquake Engineering ◽  
Critical State ◽  
Pressure Ratio ◽  
Excess Pore Pressure ◽  
Liquefaction Potential ◽  
Triaxial Cell ◽  
Excess Pore

Silt tailings (slimes) are difficult materials to test in that, like sands, it is extremely difficult to obtain undisturbed samples and subsequently re-establish them in a triaxial cell for element testing in a laboratory in anything approaching their in situ condition. Evaluation of silt tailing behaviour has to depend on in situ tests, and the piezocone (CPTu) in particular. However, CPTs in silt generate substantial excess pore pressure and there is no established methodology to evaluate the measured responses in terms of soil properties, as drained sand-based CPT interpretation is inapplicable. A case history of particularly loose silt tailings is reported in which the National Center for Earthquake Engineering Research (NCEER) liquefaction assessment method would lead to uncertainty in the liquefaction potential. However, the extremely high CPTu excess pore pressure ratio, Bq, and low dimensionless CPT resistance, Qp, at this site indicates liquefaction is likely occurring during pushing of the CPT. Detailed finite element simulations of the CPT using a critical state model provided an effective stress framework to evaluate the in situ state parameter of the silt from the measured CPT data. This framework shows that the group of dimensionless CPT variables Q(1 – Bq) + 1 is fundamental for the evaluation of undrained response during CPT sounding. And, despite the high silt content, the interpretation indicates that the tailings are indeed liquefiable.Key words: liquefaction, CPT, silt, finite element, critical state.

Pore pressure response analysis for earthquakes

1985 ◽  
Vol 22 (4) ◽  
pp. 466-476 ◽  
Author(s):  
Ashok K. Chugh ◽  
J. Lawrence Von Thun
Keyword(s):  
Pore Pressure ◽  
Effective Stress ◽  
Computer Programs ◽  
Pressure Response ◽  
Response Analysis ◽  
Earthquake Loading ◽  
Ground Response ◽  
Ground Response Analysis ◽  
Soil Deposits ◽  
Pore Pressure Response

Modifications and extensions made to the computer programs APOLLO and GADFLEA for studying the generation and dissipation of pore water pressure in soil deposits under earthquake loading are presented. The revised versions of these computer programs permit a fuller use of the analytically estimated site-specific earthquake response of soil deposits. These changes do not, however, alter the basic formulation of the problem and the solution strategies implemented in the computer programs APOLLO and GADFLEA. It is argued that the dynamic pore pressure response results obtained through these programs when used iteratively with the total stress ground response analysis should yield results close to the true effective stress ground response analysis for earthquake loading. Key words: pore pressure, earthquakes, soil dynamics, analysis, effective stress, computer programs, liquefaction.

scholarly journals Effect of Deep Mixing Grid Spacing On The Settlement of Liquefied Soil, Using Numerical Approach

2022 ◽  
Author(s):  
Fereshteh Rahmani ◽  
Seyed Mahdi Hosseini
Keyword(s):  
Pore Pressure ◽  
Ground Improvement ◽  
Pressure Ratio ◽  
Soil Layer ◽  
Excess Pore Pressure ◽  
Analysis Model ◽  
Liquefaction Mitigation ◽  
Deep Mixing ◽  
Liquefiable Soil ◽  
Excess Pore

Abstract Liquefaction occurs in a loose and saturated sand layer, induces quite large damages to infrastructures, the importance of liquefaction mitigation has been emphasized to minimize earthquake disasters for many years. Many kinds of ground improvement techniques based on various improvement principles have been developed for liquefaction mitigation. Among them, deep mixing method with grid pattern was developed for liquefaction mitigation in the 1990s, where the grid of stabilized column walls functions to restrict the generation of excess pore pressure by confining the soil particle movement during earthquake. In this study, a parametric study of the grid-form deep mixing wall is performed using numerical modeling with GID+OpenSees interface V2.6.0. The finite element method with a three-dimensional analysis model can be used to estimate the foundation settlement over liquefiable soil layer. The validity of the developed model was evaluated by comparing the results obtained from the model with the results of numerical studies and the experimental centrifuge test to investigate the effect of deep mixing grid wall on the settlement and generation of excess pore pressure ratio of liquefiable soil. Based on the analysis, the settlement for improved soil was 69% smaller than the settlement for unimproved soil. The results also indicated that the grid wall space, relative density, and stiffness ratio between soil-cement columns and enclosed soil plays an important role in the occurrence of liquefaction and volumetric strains.

scholarly journals Seismic Ground Response Analysis of Input Earthquake Motion and Site Amplification Factor at KUET

2021 ◽  
pp. 45-54
Author(s):  
Sonia Akter
Keyword(s):  
Ground Motion ◽  
Shear Wave Velocity ◽  
Amplification Factor ◽  
Site Response ◽  
Site Amplification ◽  
Response Analysis ◽  
Ground Response ◽  
Ground Response Analysis ◽  
Kobe Earthquake ◽  
Earthquake Motion

Ground motion is the movement of the earth's surface due to explosions or the propagation of seismic waves. In the seismic design process, ground response analysis evaluates the impact of local soil conditions during earthquake shaking. However, it is difficult to determine the dynamic site response of soil deposits in earthquake hazard-prone areas. Structural damage has a great influence on the selection of input ground motion, and in this study, the importance of bedrock motion upon the response of soil is highlighted. The specific site response analysis is assessed through “DEEPSOIl" software with an equivalent linear analysis method. Furthermore, four input motions including Kobe, LomaGilroy, Northridge, and Chi-Chi were selected to obtain normalized response spectra. This study aims to obtain the site amplification of ground motion, peak spectral acceleration (PSA), and maximum peak ground acceleration (PGA) based on shear wave velocity from the detailed site-specific analysis of Bangabandhu Sheikh Mujibor Rahman hall at Khulna University of Engineering & Technology. The maximum shear wave velocity obtained was 205 m/s while the amplification factor varied from 4.01 (Kobe) to 1.8 (Northridge) for rigid bedrock properties. Furthermore, the Kobe earthquake produced the highest (4.3g) PSA and the Northridge earthquake produced the lowest (1.08g) PSA for bedrock, with Vs=205 m/s. The surface PGA values were acquired in the range of 0.254g (Northridge) to 0.722g (Kobe), and the maximum strain values for Kobe earthquakes were in the range of 0.016 to .303. Therefore, the surface acceleration values were very high (>0.12g) for the Kobe earthquake motion.

scholarly journals Comparative Study on Seismic Response of Pile Group Foundation in Coral Sand and Fujian Sand

2020 ◽  
Vol 8 (3) ◽  
pp. 189 ◽  
Author(s):  
Qi Wu ◽  
Xuanming Ding ◽  
Yanling Zhang ◽  
Zhixiong Chen
Keyword(s):  
Dynamic Response ◽  
Pore Pressure ◽  
Pressure Ratio ◽  
Physical And Mechanical Properties ◽  
Bending Moment ◽  
Horizontal Displacement ◽  
Shaking Table ◽  
Excess Pore Pressure ◽  
Coral Sand ◽  
Excess Pore

The physical and mechanical properties of coral sand are quite different from those of common terrestrial sands due to the special marine biogenesis. Shaking table tests of three-story structures with nine-pile foundation in coral sand and Fujian sand were carried out in order to study the dynamic response characteristics of pile-soil-structure system in coral sand under earthquake. The influence of shaking intensity on the dynamic response of the system was taken into consideration. The results indicated that the peak value of the excess pore pressure ratio of coral sand was smaller than that of Fujian sand under two kinds of shaking intensities; moreover, the development speed of excess pore pressure ratio of coral sand was smaller than that of Fujian sand. The liquefaction of coral sand was more difficult than Fujian sand under the same relative density and similar grain-size distribution. The horizontal displacement, settlement, column bending moment, and pile bending moment of coral sand were smaller than those of Fujian sand, respectively. The magnification effect of column bending moment of buildings in coral sand was less than that in Fujian sand with increasing shaking intensity. This study can provide some supports for the seismic design of coral reef projects.

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.

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