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shear-waves
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The Effect of Fines Content and its Type on Shear Wave Velocity and Liquefaction Resistance of Sandy Soils
, Ph.D. Dissertation Sharif University of Technology ; Ahmadi, Mohammad Mehdi (Supervisor)
Abstract
Liquefaction is one of the most destructive geotechnical phenomena, and so the determination of soil liquefaction is very important. Shear wave velocity measurement is one of the methods of the soil liquefaction potential evaluation. The use of this method has increased substantially in recent years, due to its advantages compared to other methods, especially for microzonation of liquefaction potential. However, proposed curves for liquefaction evaluation which are based on the shear wave velocity measurement are more conservative than curves based on SPT and CPT, especially for sands containing fines. Local information from sites that have been liquefied previously and the shear wave...
Influence of fines content and type on the small-strain shear modulus of sand
, Article Scientia Iranica ; Vol. 21, issue. 4 , 2014 , p. 1281-1296 ; Ahmadi, M. M ; Sharif University of Technology
Abstract
The small-strain shear modulus, Go, is an important fundamental soil property. Although many studies have been conducted on this property for clean sands and pure clays, small-strain behavior for mixtures of sand and fines has been less addressed. This paper presents the results of a comprehensive laboratory study on G0 value of sand containing various amounts of different fines. To this aim, bender elements were integrated into a conventional triaxial apparatus, and shear wave velocity was measured on samples of sand with different amounts of highly-plastic, medium-plastic, low-plastic, or non-plastic fines at different void ratios. Measuring the shear wave velocity and thus...
Scattering of an anti-plane shear wave by an embedded cylindrical micro-/nano-fiber within couple stress theory with micro inertia
, Article International Journal of Solids and Structures ; Volume 58 , April , 2015 , Pages 73-90 ; 00207683 (ISSN) ; Goodarzi, A ; Delfani, M. R ; Haftbaradaran, H ; Sharif University of Technology
Elsevier Ltd
2015
Abstract
The inadequacy of traditional theory of elasticity in describing such a phenomenon as dispersion associated to a propagating wave with wavelength comparable to the intrinsic length of the medium of interest is well-known. Moreover, under certain circumstances it is incapable of capturing all the propagating waves. A remedy to such dilemmas is the employment of the more accurate higher order continuum theories which give rise to the appearance of at least one new characteristic length in the formulation. The experimental evidences as well as lattice dynamic analysis suggest that, although higher order continuum theories result in some improvements, but cannot fully overcome the...
Correlation of shear wave velocity with liquefaction resistance for silty sand based on laboratory study
, Article 15th Asian Regional Conference on Soil Mechanics and Geotechnical Engineering, ARC 2015: New Innovations and Sustainability, 9 November 2015 through 13 November 2015 ; 2015 , Pages 794-799 ; Ahmadi, M. M ; Sharif University of Technology
Asian Regional Conference on Soil Mechanics and Geotechnical Engineering
2015
Abstract
Several methods have been used for the evaluation of liquefaction potential, among which the simplified method is mostly used. In this method, which is mainly based on standard penetration test (SPT), cone penetration test (CPT) and shear wave velocity (Vs) measurement, a boundary curve is provided to separate the liquefiable and non-liquefiable soil zones. Vs measurement is a good alternative method of penetration-based methods (SPT and CPT). This is especially true in micro-zonation of liquefaction potential. Although relatively large studies have been carried out to establish the correlation between Vs and liquefaction resistance for sands; there are uncertainties about the effects of...
Effect of fines type and content of sand on correlation between shear wave velocity and liquefaction resistance
, Article Geotechnical and Geological Engineering ; 2016 , Pages 1-20 ; 09603182 (ISSN) ; Ahmadi, M. M ; Sharif University of Technology
Springer International Publishing
Abstract
The use of shear wave velocity (Vs) measurements as an in situ test for evaluation of liquefaction potential has increased substantially due to its advantages. Relatively large numbers of studies have been performed to establish the correlation between Vs and liquefaction resistance (CRR) of clean sands. Usually, natural sands contain silt and/or clay, and previous studies have shown that both the amount of fines and their nature influence the values of CRR as well as Vs. Therefore, the CRR–Vs correlations may also be affected by fines content and type of sandy soils. However, effect of fines content and especially fines type of sandy soils on the correlation between Vs and CRR is...
Soil-Structure interaction effect on fragility curve of 3D models of concrete moment-resisting buildings
, Article Shock and Vibration ; Volume 2018 , 2018 ; 10709622 (ISSN) ; Rahimzadeh Rofooei, F ; Nekooei, M ; Sharif University of Technology
Hindawi Limited
2018
Abstract
This paper presents the probabilistic generation of collapse fragility curves for evaluating the performance of 3D, reinforced concrete (RC) moment-resisting building models, considering soil-structure interaction (SSI) by concentration on seismic uncertainties. It considers collapse as the loss of lateral load-resisting capacity of the building structures due to severe ground shaking and consequent large interstory drifts intensified by P-Δ effects as well as the strength and stiffness deterioration of their lateral load carrying systems. The estimation of the collapse performance of structures requires the relation between the intensity measure (IM) and the probability of collapse...
An embedded couple stress micro-/nano-obstacle with micro-inertia incident upon by SH-waves
, Article Acta Mechanica ; Volume 229, Issue 8 , 2018 , Pages 3333-3354 ; 00015970 (ISSN) ; Ghafarollahi, A ; Sharif University of Technology
Springer-Verlag Wien
2018
Abstract
An elliptic micro-/nano-obstacle bonded to an infinite body incident upon by SH-waves, where both domains are couple stress media with micro-inertia, is of major concern. The formulation of this problem in the mathematical framework of couple stress elasticity with micro-inertia leads to angular and radial Mathieu differential equations which are solved analytically. These equations carry two characteristic lengths which are peculiar to the discrete nature of each domain enabling the capture of size effect, dispersion phenomenon, as well as the enhancement of the accuracy of the results. For verification, the ratio of the semi-axis of the elliptic obstacle is set equal to 1, and the result...
Requirements for soil-specific correlation between shear wave velocity and liquefaction resistance of sands
, Article Soil Dynamics and Earthquake Engineering ; Vol. 57, issue , 2014 , pp. 152-163 ; ISSN: 02677261 ; Akbari Paydar, N ; Sharif University of Technology
Abstract
The application of the simplified method for evaluating the liquefaction potential based on shear wave velocity measurements has increased substantially due to its advantages, especially for microzonation of liquefaction potential. In the simplified method, a curve is proposed to correlate the cyclic resistance ratio (CRR) with overburden stress-corrected shear wave velocity (Vs1). However, the uniqueness of this curve for all types of soils is questionable. The objective of this research is to study whether the correlation between CRR and Vs1 is unique or not. Besides, the necessity of developing the soil-specific correlations is also investigated. Based on laboratory test data, a new...
Scattering of SH-waves by an elliptic cavity/crack beneath the interface between functionally graded and homogeneous half-spaces via multipole expansion method
, Article Journal of Sound and Vibration ; Volume 435 , 2018 , Pages 372-389 ; 0022460X (ISSN) ; Shodja, H. M ; Sharif University of Technology
Academic Press
2018
Abstract
In this study, based on multipole expansion method an analytical treatment is presented for the anti-plane scattering of SH-waves by an arbitrarily oriented elliptic cavity/crack which is embedded near the interface between exponentially graded and homogeneous half-spaces. The cavity is embedded within the inhomogeneous half-space. The boundary value problem of interest is solved by constructing an appropriate set of multipole functions which satisfy (i) the governing equation in each half-space, (ii) the continuity conditions across the interface between the two half-spaces, and (iii) the far-field radiation and regularity conditions. The analytical expressions for the scattered...
Scattering of SH-waves by a nano-fiber beneath the interface of two bonded half-spaces within surface/interface elasticity via multipole expansion
, Article International Journal of Solids and Structures ; Volume 130-131 , 2018 , Pages 258-279 ; 00207683 (ISSN) ; Shodja, H. M ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
The present work aims to study the anti-plane scattering of SH-waves by an elastic micro-/nano-fiber which is embedded near the interface between exponentially graded and homogeneous half-spaces incorporating interface effects. The fiber is perfectly bonded to the inhomogeneous medium. It is well-known that traditional elasticity theory is incapable of accounting accurately for the nanoscopic-interfaces and, likewise, inappropriate for the prediction of the behavior of nano-sized structures where the surface-to-volume ratio is remarkably large. In the present study, the interface effects are incorporated using the well-known (Gurtin and Murdoch, 1975) surface elasticity theory which permits...
Comparison of Slopes' Pgds Derived From Newmark Rigid Block Theory With 1g Shaking Table Model Tests
, M.Sc. Thesis Sharif University of Technology ; Jafarzadeh, Fardin (Supervisor)
Abstract
Moderate to large magnitude earthquakes trigger hundreds to thousands of slope stability failures and landslides in coherent masses. In many earthquakes, landslides have been responsible for as much or more damage than all other seismic hazards combined. Earthquake-induced landslides have a detrimental impact on the serviceability of slopes by damaging nearby structures, roadways, utilities, power lines and communication networks. In this research large-scale shaking table model tests were conducted to study slope behavior under earthquake conditions on Sharif University shaking table. The model slopes were installed into a model box with a length of 3 m, width of 1 m, and height of 1.5 m. A...
The electro-elastic scattered fields of an SH-wave by an eccentric two-phase circular piezoelectric sensor in an unbounded piezoelectric medium
, Article Mechanics of Materials ; Vol. 75 , 2014 , pp. 1-12 ; ISSN: 01676636 ; Jarfi, H ; Rashidinejad, E ; Sharif University of Technology
Abstract
The dynamic equivalent inclusion method (DEIM) which was first proposed by Fu and Mura (1983), in its original context has some shortcomings, which were pointed out and remedied by Shodja and Delfani (2009) who introduced the new consistency conditions along with the related micromechanically substantiated notion of eigenstress and eigenbody-force fields. However, these theories are bound to elastic media with isotropic phases. The present work extends the idea of the above-mentioned new DEIM to the dynamic electro-mechanical equivalent inclusion method (DEMEIM) for the treatment of the scattering of SH-waves by a two-phase circular piezoelectric obstacle bonded to a third phase...
Comparison of liquefaction evaluation based on SPT and geophysical tests (case study: Mahabad dam, Iran)
, Article 5th International Conference on Geotechnical and Geophysical Site Characterisation, 5 September 2016 through 9 September 2016 ; Volume 1 , 2016 , Pages 657-661 ; 9780994626110 (ISBN) ; Jafarzadeh, F ; Akbari Garakani, A ; Eskandari, N ; Banikheir, M ; Jahromi, H. F ; Sharif University of Technology
Australian Geomechanics Society
Abstract
Standard Penetration Test (SPT) is the most commonly used insitu test for soil characterization, including the liquefaction resistance. Many studies have sought to correlate SPT number to cyclic resistance ratio (CRR) as a frequently-used approach for assessment of liquefaction potential. However, it has been shown that SPT has major deficiencies (e.g., inaccuracy in coarse sands and clays) which have given rise to development and utilization of new characterization methods such as geophysical tests (e.g., down-hole and cross-hole). In this paper, a comparison is made between the results of SPT and geophysical tests in three boreholes through the body and foundation of Mahabad Dam (located...
Determination of the scattered fields of an SH-wave by an eccentric coating-fiber ensemble using DEIM
, Article International Journal of Engineering Science ; Volume 46, Issue 11 , 2008 , Pages 1136-1146 ; 00207225 (ISSN) ; Mohammadi Shodja, H ; Delfani, M. R ; Sharif University of Technology
2008
Abstract
To date, the existing theories pertinent to the determination of the scattered fields of an inhomogeneity have been limited to certain topological symmetries for which the method of wave-function expansion is widely used. In the literature the wave-function expansion method has also been employed to the case involving concentric coated fiber. An alternative approach is the dynamic equivalent inclusion method (DEIM) proposed by Fu and Mura [L.S. Fu, T. Mura, The determination of elastodynamic fields of an ellipsoidal inhomogeneity. ASME J. Appl. Mech. 50 (1983) 390-396.] who found the scattered field of a single spheroidal inhomogeneity. The pioneering work of Eshelby [J.D. Eshelby, The...
Dynamic parameters of dry sand using one dimensional shaking table tests
, Article 6th International Conference on Physical Modelling in Geotechnics, ICPMG'06, Hong Kong, 4 August 2006 through 6 August 2006 ; Volume 1-2 , 2006 , Pages 279-283 ; 041541587X (ISBN); 9780415415873 (ISBN) ; Torghabeh, E. A ; Farahi Jahromi, H ; Sharif University of Technology
2006
Abstract
In this paper the dynamic properties of Babolsar dry sand was investigated through one dimensional shaking table tests. 8 models of Babolsar loose dry sand under low confining pressures, were subjected to different harmonic and irregular dynamic loadings. The container was a laminar shear box having 24 layers each moving on the lower one. The dynamic properties including shear wave velocity, maximum shear modulus and damping ratio of the samples were addressed in this project. © 2006 Taylor & Francis Group, London
Wave propagation in a three-dimensional half-space with semi-infinite irregularities
, Article Waves in Random and Complex Media ; 2021 ; 17455030 (ISSN) ; Sotoudeh, P ; Ghaemian, M ; Sharif University of Technology
Taylor and Francis Ltd
2021
Abstract
Dynamic analysis of problems with complex geometries requires utilization of numerical methods. To completely capture the effects of seismic wave propagation in a system, one must consider the structure or irregularity within its encompassing half-space. Correct consideration of half-space in a numerical model is important specially when it comes to cases where the half-space contains semi-infinite irregularities. In this study, a generalized numerical methodology is presented for dynamic analysis of a half-space with semi-infinite irregularities. The methodology is first verified through comparison with analytical solution of known problems. Then the method is employed to solve the dynamic...
Surface/interface effect on the scattered fields of an anti-plane shear wave in an infinite medium by a concentric multi-coated nanofiber/nanotube
, Article European Journal of Mechanics, A/Solids ; Volume 32 , 2012 , Pages 21-31 ; 09977538 (ISSN) ; Pahlevani, L ; Sharif University of Technology
Abstract
In this paper, the scattering of anti-plane shear waves in an infinite matrix containing a multi-coated nanofiber/nanotube is studied. Based on the fact that the surface to volume ratio for nano-size objects increases, the usual classical theories which generally neglect the surface/interface effects fail to provide reasonable results. Therefore, to analyze the problem the wave-function expansion method is coupled with the surface/interface elasticity theory. In order to provide some quantitative results through consideration of several examples, the knowledge of the relevant surface and/or interface properties of the corresponding constituent materials are required. For this reason, part of...
Introducing a method for calculating water saturation in a carbonate gas reservoir
, Article Journal of Natural Gas Science and Engineering ; Volume 70 , 2019 ; 18755100 (ISSN) ; Nabi Bidhendi, M ; Masihi, M ; Emamzadeh, A ; Sharif University of Technology
Elsevier B.V
2019
Abstract
Cementation factor greatly affects water saturation estimation. Factors such as depositional environment, diagenesis and depositional architecture make the estimation of water saturation a big challenge in carbonate reservoirs. The current study is introduced a method for calculating cementation factor in Archie formula. First, (MRGC) technique was applied on the (NMR) logging parameters along with (NDS) data to obtain the optimum number of clustering. After that, fuzzy logic method was applied on conventional log parameters obtained from the wells without any NMR log data. In the third part of the study, a novel crossplot introduced including compressional to shear-wave velocity ratio...
Characterizing the effect of fines content on the small strain shear modulus of sand-silt mixtures during hydraulic hysteresis
, Article 4th International Conference on Transportation Geotechnics, ICTG 2021, 23 May 2021 through 26 May 2021 ; Volume 165 , 2022 , Pages 837-849 ; 23662557 (ISSN); 9783030772338 (ISBN) ; Mohsen Haeri, S ; Khosravi, A ; Sharif University of Technology
Springer Science and Business Media Deutschland GmbH
2022
Abstract
Small strain shear modulus, Gmax, is one of the most important parameters for the characterization of the behavior of earth structures subjected to static or dynamic loading conditions. This research presents an experimental laboratory study on the effect of non-plastic fines content and hydraulic hysteresis on the Gmax of unsaturated sandy soils. In this regard, clean Firoozkuh No. 161 silica sand which is classified as poorly graded sand was mixed with different percentages of non-plastic Firoozkuh silt. A set of bender element tests were carried out using two modified triaxial devices. The modifications on these two apparatus were to add HAV ceramic discs for air–water control of...
A Carbonate Reservoir Characterization Using AVO Analysis on 3D Seismic Data
, Ph.D. Dissertation Sharif University of Technology ; Pishvaie, Mahmoud Reza (Supervisor) ; Javaherian, Abdolrahim (Supervisor) ; Nabi Bidhendi, Majid (Co-Advisor)
Abstract
In this project, some issues facing the application of AVO in carbonate reservoirs were studied,reviewed and discussed: physical relationships between elastic and reservoir rock properties to estimate compressional and shear wave velocities both on core measurements and well logging data, sensitivity analysis for Gassmann‐Biot and Kuster‐Toksoz rock physics models on the representative carbonate samples, lithology discrimination and reservoir characterization in carbonate intervals using AVO seismic attributes and specifically LambdaRho‐MuRho approach.The studied area (Azadegan Oil Field) is an area about 1174 km2 of 3D seismic data and was containing of six wells in the time of study. In...