Maysam Salimzadehshooiili - Assistant Professor, Department of Civil Engineering, Faculty of Technology and Engineering, University ofGuilan, Iran
AmirHossein Jamaldar - MSc in Geotechnical Engineering, Faculty of Technology and Engineering, University of Guilan, Iran
Parsa Asadi - MSc in Geotechnical Engineering, Faculty of Technology and Engineering, University of Guilan, Iran
Hesam Sabounchi - MSc in Geotechnical Engineering, Faculty of Technology and Engineering, University of Guilan, Iran.

Standard Penetration Testing (SPT) is a widely used method for soil investigation and characterization, introduced by ASTM in the ۱۹۵۰s. SPT has been used extensively in geotechnical engineering and earthquake engineering, including to evaluate soil liquefaction potential. Liquefaction occurs when saturated soil loses its strength and stiffness due to the buildup of pore water pressure during an earthquake. The relationship between SPT and liquefaction was first proposed by Seed in the ۱۹۷۰s, who developed a relationship between the SPT blow count and the cyclic stress ratio. Since then, SPT has been used to design earthquake-resistant structures, but it has limitations, and it is important to use SPT results in conjunction with other soil investigation methods to obtain a more complete understanding of the soil properties and liquefaction potential.

Spt, Liquefaction