Segregation Index—A New Soil Parameter for Internal Erosion Assessment

Abstract

Internal erosion is a major cause related to nearly half of dam dysfunctions and failures. This phenomenon occurs when loose soil particles are transported outwards the soil mass by seepage through a series of pores and pore constrictions. As loose particles are usually fine and embedded in the pores formed by the soil primary fabric, traditional methods often correlate the representative sizes of fine and coarse particles to indicate the susceptibility to internal erosion of an assessed soil. These methods are not very accurate because soil particle size distribution can vary widely with several identical key sizes. This paper presents a new indicator for internal erosion assessment using the probability to be transported of loose particles: the segregation index. This index is estimated experimentally and analytically for the correlation with internal erosion test results. The index also has a significant role in the estimation of real effective stress of soils.