Evaluation of Heave Behavior by Numerical Modeling of Granular Pile Anchor in Expansive Soil

Abstract

Expansive soil considered as extremely problematic soil which causes distress of structural elements. This is due to the swelling and shrinkage characteristics on water absorption and reduction, respectively. In view of construction in an expansive clay bed requires creative and innovatory methods for improving the ground, one among such solutions is granular pile anchor (GPA) and further modified as granular pile anchor foundation (GPAF). GPAF system resembles type of pile foundation which is capable to arrest the detrimental effects of expansive soil. In GPA system, anchorage is achieved through the anchor rod provided at the center of the pile, which connects the footing steel plate with anchor steel plate provided at bottom. Granular pile anchor controls the swelling/heave behavior of expansive soil due to the friction mobilized along the pile–soil interface and reduces the upliftment of footing. This paper attempts to study the heave behavior of GPA in expansive soil by numerical modeling with and without geogrid encasement using PLAXIS 2D. Heave phenomena of expansive clay bed reinforced with plain GPA and geogrid-encased GPA for three different pile lengths were analyzed. Effect of roughness coefficient (Rinter) on geogrid-encased GPA was also analyzed. Results of this study revealed that the heave behavior of GPA in expansive soil is reduced by increasing the length of pile, and further reduction in heave is achieved around 64% by providing the geogrid encasement around the pile length. It was also found that heave reduces significantly with increase in roughness coefficient (Rinter). Maximum percentage reduction in heave was achieved up to 35% by varying Rinter values.KeywordsExpansive soilGranular pile anchorGeogrid encasementHeave behavior