IMPROVED FILTER CRITERION FOR COHESIONLESS SOILS

The behavior of filters for cohesionless base soil has been studied by 2 means: physical modeling of soil particle transport, and statistical analysis of overall filter behavior. The two methods are used interactively, in the sense that the understanding obtained from physical modeling is used to guide the statistical analysis and interpret its results. The practical outcome of the study is an improved filter design criterion for cohesionless base soil. Conclusions drawn on the basis of the results of a physical soil transport model, and on statistical anaysis of existing laboratory data, are presented. It was found that DF15/DB85, which is used in Terzaghi' filter criterion, is the grain size parameter with the highest explanatory power on filter performance.