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Showing 6 results for Wave Propagation

Shahram Feizee Masouleh, Kazem Fakharian,
Volume 6, Issue 3 (9-2008)
Abstract

A finite-difference based continuum numerical model is developed for the pile-soil dynamic response during pile driving. The model is capable of simulating the wave propagation analysis along the pile shaft and through the soil media. The pile-soil media, loading and boundary conditions are such that axisymmetric assumption seems to be an optimized choice to substantially reduce the analysis time and effort. The hydrostatic effect of water is also considered on the effective stresses throughout the soil media and at the pilesoil interface. The developed model is used for signal matching analysis of a well-documented driven pile. The results showed very good agreement with field measurements. It is found that the effect of radiation damping significantly changes the pile-soil stiffness due to the hammer blow. The pile tip response shows substantial increase in soil stiffness below and around the pile tip due to driving efforts.
F. Jafarzadeh, H. Farahi Jahromi, E. Abazari Torghabeh,
Volume 8, Issue 2 (6-2010)
Abstract

Investigating the parameters influencing the behavior of buried pipelines under dynamic loading is of great

importance. In this study the soil structure interaction of the pipelines with the surrounding soil was addressed using

shaking table tests. Wave propagation along the soil layers was also included in the study. The semi infinite nature of

the field was simulated using a laminar shear box. The soil used in the experiments was Babolsar coastal sand (Iran).

PVC pipes were used due to their analogy with the field. Eight models were constructed with the first four models

having uniform base. In the next models, the non-uniformities of real ground were simulated using a concrete pedestal

installed at the very bottom of the shear box. Pipe deformations under dynamic loading, acceleration distribution in

height, soil settlement and horizontal displacements were measured by strain gauges, acceleratometers and

displacement meters. Analyzing the obtained data, influence of different parameters of dynamic loading such as

acceleration, frequency, soil density, base conditions and shaking direction to pipe axis on the acceleration

amplification ratio and pipe deformation were investigated. Also in order to study the effect of dynamic loading on two

different materials, soil and pipe, the horizontal strains were compared


M. Afzalirad, M. Kamalian, M. K. Jafari, A. Sohrabi-Bidar,
Volume 12, Issue 1 (1-2014)
Abstract

In this paper, an advanced formulation of time-domain, two-dimensional Boundary Element Method (BEM) with material damping is presented. Full space two-dimensional visco-elastodynamic time-convoluted kernels are proposed in order to incorporate proportional damping. This approach is applied to carry out site response analysis of viscoelastic topographic structures subjected to SV and P incident waves. Seismic responses of horizontally layered site, semi-circular canyons, slope topography and ridge sections subjected to these incident waves are analyzed in order to demonstrate the accuracy of the kernels and the applicability of the presented viscoelastic boundary element algorithm. The results show an excellent agreement with recent published results obtained in frequency domain. Also, the effects of different material damping ratios on site response are investigated.
I. Ashayeri, M. Kamalian, M. K Jafari, M. Biglari, Ma. Mirmohammad Sadeghi,
Volume 12, Issue 2 (4-2014)
Abstract

This paper presents time domain fundamental solutions for the extended Biot's dynamic formulations of two-dimensional (2D) unsaturated poroelasticity. Unsaturated porous media is considered as a porous media in which the voids are saturated with two immiscible fluids, i.e. liquid and gas. At first, the corresponding explicit Laplace transform domain fundamental solution is obtained in terms of skeleton displacements, as well as liquid and gas pressures. Subsequently, the closed-form time domain fundamental solutions are derived by analytical inversion of the Laplace transform domain solutions. Finally, a set of numerical results are presented which verifies the accuracy of the analytically inversed transient fundamental solution and demonstrates some salient features of the elastic waves in unsaturated media..
Jafar Najafizadeh, Mohsen Kamalian, Mohammad Kazem Jafari, Naser Khaji,
Volume 12, Issue 3 (7-2014)
Abstract

In this paper, an advanced formulation of the spectral finite element method (SFEM) is presented and applied in order to carry out site response analysis of 2D topographic structures subjected to vertically propagating incident in-plane waves in time-domain. The accuracy, efficiency and applicability of the formulation are demonstrated by solving some wave scattering examples. A numerical parametric study has been carried out to study the seismic response of rectangular alluvial valleys subjected to vertically propagating incident SV waves. It is shown that the amplification pattern of the valley and its frequency characteristics depend strongly on its shape ratio. The natural frequency of the rectangular alluvial valley decreases as the shape ratio of the valley decreases. The maximum amplification ratio along the ground surface occurs at the center of the valley. A simple formula has been proposed for making initial estimation of the natural period of the valley in site effect microzonation studies.
R. Tarinejad, S. Pirboudaghi,
Volume 13, Issue 2 (6-2015)
Abstract

It is well-known that dam-reservoir interaction has significant effects on the response of dams to the earthquakes. This phenomenon should be considered more exactly in the seismic design of dams with a rational and reliable dynamic analysis method. In this research, seismic analysis of the dam-reservoir is studied as a wave propagation problem by using Legendre Spectral element method (SEM). The special FEM and SEM codes are developed to carry out the seismic analysis of the dam-reservoir interaction system. The results of both SEM and FEM models are compared considering the accuracy and the time consumption of the analysis. Attractive spectral convergence of SEM is obtained either by increasing the degree of the polynomials in the reservoir or by the number of elements of dam. It is shown that all boundary conditions of the reservoir domain in the SEM are evaluated by the exact diagonal matrices. The SEM leads to the diagonal mass matrix for both dam and reservoir domains. The stiffness matrices obtained from the SEM are more sparse than the corresponding stiffness matrices in the FEM consequently the SEM needs a significant less time consumption of the analysis.



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