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Liquefaction Potential Index (LPI) calculation procedure <br />Calculation of the Liquefaction Potential Index (LPI) is used to interpret the liquefadion assessment calculations in terms of <br />severity over depth. The calculation procedure is based on the methology developed by Iwasaki (1982) and is adopted by AFPS. <br />To estimate the severity of liquefaction extent at a given site, LPI is calculated based on the following equation: <br />20 <br />LPI = f (10-0,5z) x FE xd, <br />where: <br />FL=1-F.S. when F.S. less than 1 <br />F, = O when F.S. greater than 1 <br />z depth of measurment in meters <br />Values of LPI range between zero (0) when no test point is charaderized as liquenable and 100 when all points are characterized <br />as susceptible to liquefaction. Iwasaki proposed four (4) discrete categories based on the numeric value of LPI: <br />• LPI = O :Liquefaction risk is very low <br />• 0 < LPI <= 5 : Liquefaction risk is low <br />• 5 < LPI < = 15 : Liquefaction risk is high <br />• LPI > 15 :Liquefaction risk is very high <br />FL <br />1.0 2.0 0 1( <br />0 <br />00 <br />0 <br />5-5- <br />10 -10Depth 2 (m) <br />7 <br />Graphical presentation of the LPI calculation procedure <br />CLiq v. 1.5.1.16 - CPT Uquefaction Assessment Software 54 <br />15 -15 - <br />20 <br />20