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Showing 4 results for Hosseini

H. Shahnazari, M. Esmaeili, H. Hosseini Ranjbar,
Volume 8, Issue 2 (6-2010)

Considerations on the explosion resistant design of special infrastructures have increased in the recent

years. Amongst the various types of infrastructures, road and railway tunnels have a unique importance due to their

vital role in connection routes in emergency conditions. In this study, the explosion effects of a projectile impacting on

a railway tunnel located in a jointed rock medium has been simulated using 2D DEM code. Primarily, a GP2000

projectile has been considered as a usual projectile and its penetration depth plus its crater diameter were calculated

in rock mass. The blast pressure was, then, calculated via empirical formula and applied on the boundary of crater as

input load. Finally, the wave pressure propagation through the jointed rock medium was investigated. In part of the

study a sensitivity analysis has been carried out on jointed rock parameters such as joint orientation, dynamic modulus

and damping ratio. Their effects on tunnel lining axial force as well as bending moment have also been investigated.

S.m. Mir Mohammad Hosseini, A.a. Hajimohammadi, A. R. Hajimohammadi,
Volume 8, Issue 2 (6-2010)

Seismic piezocone device (SCPTu) together with Resonant Column and Cyclic Triaxial test apparatus are

employed to measure small strain shear modulus (G0) of carbonate sandy and clayey soils of southern coasts of Iran.

A large area of southern regions of Iran is formed from clay, silt and sand. In this study, maximum shear modulus that

is derived from both field (by seismic piezocone) and laboratory (by Resonant Column and Cyclic Triaxial) tests on

soil samples from the southern region, indicated a meaningful effect of sample disturbance. Results show that in

laboratory tests, loose samples tend to become denser and therefore exhibit greater stiffness whereas dense samples

tend to become looser, showing a reduction in stiffness. According to the results of the present study, there are narrow

limits of soils shear moduli for which the laboratory tests and the field measurements yield approximately the same

amounts. This limit of shear moduli is about 30-50(MPa) for clay deposits and 70-100 (MPa) for sandy deposits. Since

the shear moduli of soils in small strains can also be computed from the shear wave velocity, also correlations based

on parameters derived from SCPTu test for shear wave velocity determination of sandy and clayey soils of the studied

area are presented. This study shows that shear wave velocity can be related to both corrected tip resistance and total

normal stress. The measurements of the damping ratio and shear module, because of a great disturbance of stiff

deposits during the sampling process and also due to considerable differences between the laboratory and field

results, by the laboratory approaches are not reliable and advised.

S.a.o. Hosseini, M. Nasiri, M. Akbarimehr,
Volume 13, Issue 3 (Transaction A: Civil Engineering, September 2015)

Harvesting of timber using ground based machinery is still a common practice around the world. Track and road building, and movement of machinery during harvesting operations cause soil disturbance. Therefore the aim of this study was to investigate the change in soil properties after logging operation on skid trails (2 years and 7 years after logging) and compare disturbed soil properties with control sampling (undisturbed soil). For this purpose, soil samples were collected from the skid trail and undisturbed area. Electrical conductivity, pH, organic carbon, moisture equivalent, moisture, total porosity and bulk density were determined on the skid trail and undisturbed area. Soil characteristics were examined in two ages (2 years and 7 years skid trail). There were crucial differences in the values of electrical conductivity, organic carbon, moisture, total porosity and bulk density from skid trail and undisturbed area in 2 years skid trail (p<0.05). But on 7 years skid trail, there were no significant differences in values of mentioned factors from skid trail and undisturbed area (p>0.05) except bulk density (p=0). It has been concluded that 7 years after logging, all soil properties except bulk density were completely recovered on skid trail. These findings have important implications for assessing the impact of skidders traffic and recovery time in skid trails.
Alireza Darvishpour, Ali Ghanbari, Seyyed Ali Asghar Hosseini, Masoud Nekooei,
Volume 15, Issue 3 (Transaction B: Geotechnical Engineering 2017)

Most of the proposed methods for obtaining the free vibration natural frequency of the retaining wall have been presented, assuming the behavior of the wall in two-dimensional domain, and they are not able to express the three-dimensional behavior of these structures in a satisfying manner. In this paper, the plate theory is employed to analyze the free vibration of wall-soil system in three-dimensional domain. So the retaining wall is modeled as a clamped-free plate and the stiffness of the soil existing behind the wall is modeled as a set of springs. Using the approximate Rayleigh method, new analytical expression for obtaining the free vibration natural frequencies for the three first modes of the wall is represented. The results of the proposed model are compared with both the results of the other researchers and the ones from finite element method (FEM). They are also compared with the results of a full-scale experiment and it shows a good agreement. The comparison shows that modeling the wall in two-dimensional form is not accurate enough to calculate all the natural frequencies of the wall. The results of this paper show that there is a considerable difference between two- and three-dimensional behavior of the walls. The proposed method also gives the free vibration natural frequencies of the wall extensional modes with an acceptable accuracy. Finally, the effect of tensile and compressive behavior of the soil on the fundamental frequency is studied. This research can be considered as a new field in three-dimensional calculation of the retaining walls.

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