• Gholam Reza Lashkaripour

      Articles written in Journal of Earth System Science

    • Dynamic soil properties of some deep trenches in Mashhad city, NE Iran

      Azam Ghazi Naser Hafezi Moghadas Hossein Sadeghi Mohammad Ghafoori Gholam Reza Lashkaripour

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      Microtremor survey is achieved in order to evaluate the dynamical characteristics of surface layers. For this purpose, 13 trenches were selected and microtremor measurements were performed at the top and bottom of each trench. Floor spectral ratio (FRS) analysis was accomplished to obtain frequency and amplification of the trenches. The results of microtremor were compared with 1D equivalent linear analysis. Most of the fundamental frequencies obtained by 1D analysis are in good agreement with those calculated by microtremor technique. Irregularities in surface and subsurface geomorphic conditions tend to have differences in results obtained by both mentioned methods. Damping ratios were derived from the half power bandwidth method. The damping ratio varied between 2.1 in fine grain soils and 6.6 in sand soils.

    • Estimating shear wave velocity of soil using standard penetration test (SPT) blow counts in Mashhad city

      Omolbanin Ataee Naser Hafezi Moghaddas Gholam Reza Lashkaripour

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      This study investigates the correlation between shear wave velocity (V$_{S}$) and standard penetration test blow counts (SPT-N value) in all soil types, gravelly soil, sandy soil and clayey soil for Mashhad city in the north eastern region of Iran. The V$_{S}$ data used were measured through downhole method in 84 construction projects (in 88 boreholes). From among collected data, 424 pairs of V$_{S}$-SPT recorded in one depth were used for regression analysis. The obtained results showed that the N-value had a critical role in estimating V$_{S}$ and soil type was less effective in this regard. These findings are in line with the findings of the previous studies. Regression equations obtained in this study were compared with correlations from previous studies. There was a relative similarity between the previously published and the new regression equations for Iranian soils. Although almost all correlations follow a similar trend, there are significant differences between new equations and correlations reported for other countries. The regression coefficients of the new equations show the acceptable capability of the suggested correlations in estimating V$_{S}$ through SPT-N value. Therefore, these equations can be used to estimate V$_{S}$ for the soils of the current study area and for other similar areas. Moreover, V$_{S30}$ was used for site classification of the study area as per National Earthquake Hazard Reduction Program (NEHRP) guidelines and it was shown that a major portion of the city comes under site class C and other locations are categorised as site class D.

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