Effect of Tension on Stability of Embankments

An expression is derived by which the line of thrust for effective stress through an embankment can be obtained from the line of thrust for total stress. The effect of tension in the soil at the top of an embankment is considered and an expression is proposed for determining the depth of tension cracks. A method of analysis for the stability of embankments is described which takes into account the effect of water pressure in the tension crack; it is assumed in this method that the interslice forces for total stress are parallel. It is shown that, over a wide range of embankment stability problems, this method leads to a reasonable position for the line of thrust for effective stress. Charts are given relating the ratio of the depth of the tension crack to the total height of the embankment in terms of three parameters: slope, pore-pressure co-efficient and factor γ Ht tan φ'/c'. It is also shown that the position of the thrust line is also determined by these same parameters.