ABSTRACT
Soil gradation is used to establish the potential for internal erosion. However, many projects were built before methods to estimate unstable soils were available and may need to be evaluated concerning the hydro-mechanical conditions that may trigger erosion. Hydro-mechanical boundaries can be deduced by performing permeameter tests. For a given effective stress, the critical hydraulic gradient depends mainly on soil gradation. Similarly, load transfer to the finer fractions depends directly on the soil gradation. Therefore, it is believed that a link between soil gradation and hydro-mechanical boundary. Numerical models were performed to determine the load transferred to the finer fraction. Results are compared with previous research and show that the portion of stress carried by the finer fraction decreases rapidly with increasing the ratio D15´/d85 ´ proposed by Kezdi (1979). Based on this and previous research findings, an approximate procedure is proposed to estimate the hydromechanical boundary.
