Modify Geometrical Approaches to Assess Internal Instability by Statistically Analyses

Internal Instability is a form of erosion occurred in non-cohesive soils, frequently. Moving of soil particles through the soil structure is the main reason to occur this phenomenon. So, grain size distribution and porosity of soils are the most important factors that influence on this process. Up to now, many methods have been proposed to predict Internal Instability which the validation of them are less clear because most available criteria are based on tests on limited soils. In this research performance of some methods developed based on soil porosity have been investigated. To do this, some soil samples with different porosity and aggregation have been subjected to experimental test and their suffusion possibility is compared with selected criteria. Results show low accuracy to evaluate Internal Instability for selected criteria. Some samples are recognized stable, whereas they are experienced suffusion and vice versa. Finally, statistically analyses have been developed to modify these methods based on physical properties of soil. Keywords: Internal Instability, Suffusion, Soil Porosity, Aggregation, Statistically Analysis.