Liquefaction Occurrence Risk Analysis Considering
Graduate Student, Mazandaran University, Babol, Iran
Associate Professor, Mazandaran University, Babol, Iran
Assistant Professor, Tarbiat Moallem (Kharazmi) University, Tehran, Iran
In liquefaction potential studies, Seed "simplified" method is widely used to estimate CSR. The site conditions and earthquake specifications are ignored in this method. So it is necessary to evaluate the earthquake induced stresses using soil response analysis or the new relations developed to calculate the stress reduction coefficient (rd) must be used. In this study we investigate Tehran South-East that is prone to liquefaction according to the basic surveys. The shear stresses resulted from earthquake are estimated through soil response analysis, using EERA software. EERA evaluates the soil dynamic response by resolving the differential equation of wave motion in alluvium with horizontal layers through equivalent linear method. Soil strength stress is calculated using SPT results through various methods. With comparison of these two stresses, the liquefaction reliable coefficient in soil different layers is evaluated and high-risk regions of liquefaction are identified. The results show the regions prone to liquefaction occurrence. In these specified boreholes the liquefaction risk is analyzed and seismic risk curve is estimated for different seismograph, return cycles and epicentral distance. Finally, with eliminating the acceleration between the seismic risk curve and the liquefaction occurrence on surface curve, the probability of increase of any amount of liquefaction is identified. A high probability of liquefaction occurrence on surface is obtained for many cases.
Keywords: Liquefaction, Soil Response Analysis, Equal Linear Method, Risk Analysis, Tehran S-E.
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