Abstract
<p>Shear wave velocity, V<sub>s</sub>, is one of the important input parameters in seismic response analysis of the ground. Various methods have been examined to measure the soil V<sub>s</sub> directly. Direct measurement of V<sub>s</sub> is time consuming and costly, therefore many researchers have been trying to update empirical relationships between V<sub>s</sub> and other geotechnical properties of soils such as SPT Blow count, SPT-N. In this study the existence of a statistical relationship between V<sub>s</sub>, SPT-N<sub>60 </sub>and vertical effective stress, signa<sub>nu</sub>´, is investigated. Data set we used in this study was gathered from geotechnical and geophysical investigations reports. The data have been extracted from more than 130 numbers of geotechnical boreholes from different parts of Mashhad city. In each borehole the V<sub>s</sub> has been measured by downhole method at two meter intervals. The SPT test also has performed at the same depth. Finally relationships were developed by regression analysis for gravels, sands and fine grain soils. The proposed relationships indicate that V<sub>s</sub> is strongly dependent on signa<sub>nu</sub>´. In this paper the effect of fine percent also is considered on the V<sub>s</sub> estimation.</p>
Highlights
The first step in the dynamic response analysis of soil is recording the soil key properties such as density, stiffness, damping and maximum shear modulus
The purpose of the present study is to assess the correlations between Vs and soil properties using statistical methods for collected data throughout the Mashhad City in northeast of Iran (Figure 1)
Standardization of each variable is done by software before regression analysis
Summary
The first step in the dynamic response analysis of soil is recording the soil key properties such as density, stiffness, damping and maximum shear modulus. The maximum shear modulus of soil is function of the shear wave velocity, Vs, and soil density Gmax= tVs2. The Vs can be determined directly by testing undisturbed soil samples in laboratory or computed using in-situ measurements [Brandenberg et al 2010]. The Vs is used for the seismic soil classification in building codes. There are various in-situ methods for measuring Vs including seismic refraction survey, Down-hole, crosshole, seismic CPT, refraction microtremor and the spectral-analysis-of-surface-waves (SASW). It is notable that resolutions of these methods are different and depend on measurement depth, soil condition, interpretation methods and implementation details [Andrus and Stokoe 1997]
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