Correlation between shear wave velocity and standard penetration test for Nowshahr and Chalus, Iran

Estimation of ground response during earthquake is gaining much attention in recent years. One of the most important parameters needed to achieve this goal is the shear wave velocity and its related parameters in the surface layers obtained by seismic geophysical tests in place or by laboratory measurements on intact soil samples. Field measurement of such parameter is accurate, but expensive as well as time consuming. Therefore, the need to estimate shear wave velocity using other soil parameters is justified. For example, the numbers of blows (N) from standard penetration test (SPT) are readily available for many sites where geotechnical investigations are carried out. This paper presents a development of reliable correlation between Vs measured by using other soil parameters such as density and shear modulus of soil and N measured using SPT at various sites in Chalus and Nowshahr regions in Mazandaran Province. For this purpose, the results of standard penetration tests conducted in 31 different sites in Chalus and Nowshahr areas were used. Correlation relations were obtained separately for all soils, cohesive and non-cohesive soils. The relationships obtained are within the range of those obtained worldwide for other sites and are comparable to them. Moreover, present correlations, having regression coefficients (R2) almost 0.92, indicated good prediction capability. The proposed relations obtained are useful for assessment of seismic microzoning of the region.