Lateral Extension of Compacted-Fill Slopes in Expansive Soils

AbstractMany compacted embankments are composed of expansive soils. Water from landscape irrigation, precipitation, and subsurface seepage can gradually infiltrate throughout the fill and cause both vertical movement and lateral expansion of the fill-slope zone. Lateral stretching from expansion can cause distress to surface improvements and structures built near the crest of the slope. Slope inclinometers installed within the slope near the crest would register lateral movement that is the result of the fill’s lateral expansion. This paper describes the mechanism of lateral extension of expansive fill embankments and presents examples of resulting distress features. A test procedure is described for measuring wetting-induced vertical and lateral strains on compacted specimens using triaxial equipment. The paper also recommends a procedure, the lateral fill extension (LFE) method, for calculating the amounts of heave or settlement and lateral movement as a function of the slope’s geometry, the soil’s vert...