Artículo de publicación ISIPermeameter tests were performed on four widely graded cohesionless soils, to study their susceptibility to internal erosion. Test specimens were reconstituted as a saturated slurry, consolidated, and then subjected to multi-stage seepage flow under increasing hydraulic gradient. The occurrence of internal instability is described qualitatively, from visual observations through the wall of the permeameter during a test and from post-test observations; it is also described quantitatively, from change of hydraulic gradient within the specimen and from axial displacement during a test. The results provide a novel insight into the spatial and temporal progression of seepage-induced internal instability. This insight yields an improved characterization of suffusion and suffosion in cohesionless soils, the progression of which appears governed by a critical combination of hydraulic gradient and effective stress.British Columbia Hydroelectric Power Authorit

Artículo de publicación ISIResults are presented from permeameter tests involving unidirectional seepage flow through reconstituted specimens of four widely graded cohesionless soils. The onset of instability is defined by a significant decrease in local hydraulic gradient over a relatively short period of time. The novel concept of a hydromechanical path in stress (sigma'(vm)) - gradient (i(jk)) space is proposed, which describes the response to seepage flow during testing and terminates at the value of critical hydraulic gradient. The path terminus establishes a hydromechanical boundary governing the onset of seepage-induced internal instability in one-dimensional flow. The boundary represents a failure envelope, which is different for each of the four soils tested. A ranking of seepage-induced instability for each soil, from most unstable to least unstable, is found similar, but not identical to, the susceptibility to internal instability determined from empirical analysis of the gradation shape.British Columbia Hydroelectric Power Authorit