An Improved Method for Seismic Site Characterization with Emphasis on Liquefaction Phenomena

Abstract

Iran is an active seismic region and frequent earthquakes and because of the active faults, often leads to severe casual-ties caused by structural destruction. Earthquake damage is commonly controlled by three interacting factors, source and path characteristics, local geological and geotechnical conditions and type of the structures. Obviously, all of this would require analysis and presentation of a large amount of geological, seismological and geotechnical data. In this paper, nonlinear geotechnical seismic hazard analysis considering the local site effects was executed and the soil lique-faction potential analysis has been evaluated for the Nemat Abad earth dam in Hamedan province of Iran because of its important socioeconomic interest and its location. Liquefaction susceptibility mapping is carried out using a decisional flow chart for evaluation of earthquake-induced effects, based on available data such as geological, groundwater depth, seismotectonic, sedimentary features, in situ, field and laboratory geotechnical parameters. A series model tests were conducted and then on base of the achieved data the idealized soil profile constructed. A C# GUI computer code “NLGSS_Shahri” was Generate, developed and then employed to evaluate the variation of shear modulus and damping ratio with shear strain amplitude to assess their effects on site response. To verify and validate the methodology, the obtained results of the generated code were compared to several known applicable procedures. It showed that computed output of this code has good and suitable agreement with other known applicable procedures.