It is seen that there are two variables, e0 and PI, which control the CSR for initial liquefaction. Therefore, in
order to study the effect of one variable, PI, it was decided to normalize the CSR for all samples for a common
void ratio of 0.644. It was assumed that the CSR for initial liquefaction is inversely proportional to the void ratio
(Guo, 1999; Guo and Prakash 1999).