Efficacy of Geopile–Anchors in Controlling Heave of Expansive Clay Beds

Abstract

This paper presents the efficacy of a new technique in the form of geopile–anchors in arresting heave of expansive soils. Heave behaviour of a remoulded expansive clay reinforced with vertical cylindrical cells made of geogrid and filled with geomaterials (geopiles) with a central anchor inside is presented. A geogrid cylinder installed vertically in an expansive soil (forming a geopile), with an anchor inside is a geopile–anchor. In a geopile–anchor, foundation is anchored to an anchor plate at the bottom of the geopile with the help of an anchor rod. The upward movement of foundation due to swelling of clay is resisted by anchorage and by friction mobilized at the interface formed by the fill material (expansive soil)–geogrid–expansive soil. Filling the geopile with granular material can augment uplift resistance. Tests were conducted on expansive clay beds reinforced with geopile–anchors varying geopile diameter and type of geopile-fill material. In the case of group of geopile–anchors, spacing was varied and its effect on heave studied. The experimental results indicated that geopile–anchors reduced heave of expansive clay beds. With expansive clay fill, a maximum reduction in heave of 78.50% was obtained. When gravel fill was used, a percentage reduction of 92.50% was obtained. At a radial distance of 60-mm the reduction in heave obtained was 50%, 58%, 67% and 73% for single geopile–anchor, and 69%, 73%, 81% and 88% for two group geopile–anchors installed at a spacing of 2d when the fill materials were clay, fine sand, coarse sand and gravel respectively.