Soil Liquefaction Analysis Based on Geotechnical Exploration and In Situ Test Data in the Tabriz Metro Line 2

Liquefaction is one of the most important and complex topics in geotechnical earthquake engineering. During this phenomenon, pore water pressure increases as long as it will be equal to confining stresses. Hence, the effective confining stress becomes zero and the soil will not have any shear resistance. As a result the soil mass is unstable and causes much destruction. In this research, according to information from boreholes of Tabriz Urban Train Line 2 all required parameters including total stresses, pore water pressures and effective stresses, the results according to soil type and water depth for all 53 preliminary boreholes were collected and evaluation of the liquefaction potential assessment based on energy standard penetration resistance test (SPT) has been compared. The depth of standard penetration resistance test (Nspt) in which the results were not available, the interpolation method were used for all layers. For evaluation of liquefaction potential based on (SPT) method the latest techniques offered by Idriss - Boulangr (2008) were used. In this paper, calculations are presented for an earthquake of 7.5 in the scale of Richters. Then the safety factor against liquefaction is computed by these methods for several boreholes at different depths, and liquefaction risk evaluation has been done by Iwasaki method. At last by comparison of 3 sample boreholes and considering difference between them it can be concluded that some areas of Tabriz metro line 2 is located in perfect liquefaction conditions.