Modeling the shear strength improvement at the interface of lime-stabilized soil and concrete

Abstract

Drilling operations remold the shaft soil, leading to significant shear strength losses. Lime stabilization has been proposed to increase the shaft resistance capacity of friction piles installed into clayey soils. For verifying this hypothesis lime slurries can be prepared in boreholes prior to subsequent concreting. The infiltration of lime is provided by this means through the cracks and fissures that are exposed during the augering process. The benefical effects of the enabled lime-clay interaction are likely to enhance the shear resistance of the remolded interface zone. Provided that the soil characteristics of the interface have been improved, the required load bearing capacity of piles can thus be obtained without increasing its dimensions. Besides its ease and convenience, the economical aspect of this method makes this proposal even more attractive for field applications. Using the finite element method, the numerical simulations have been performed in order to distinguish the effect of lime as well as the contribution of treatment duration. A simplified finite element model has been developed under the ANSYS 5.2 computer software in order to analyze the response behavior of lime treated and untreated natural soil with concrete under identical shearing conditions. The models have been primarily founded on the mechanical parameters (Young modulus, Poisson ratio and yield stresses) of the interface soil and its surrounding semi-finite soil domain. Supporting the corresponding laboratory test results obtained formerly by Metehan C. T. (1994), figures have revealed an approximately doubled shear strength at the interface consequent to lime treatment. However, the varied interface thickness accounting for the intensity of lime infiltration, which is in turn dependent upon the duration of treatment, revealed no significant impact onto the results obtained.|Keywords: Cast-in-situ concrete piles, skin friction, lime stabilization, diffusionadvection, finite element modeling, interface, thin-layer element.