Theoretical elastic solutions for foundations improved by geosynthetic-encased columns

ABSTRACT: Based on an axisymmetric elastic model, a theoretical solution is obtained for a foundation improved by geosynthetic-encased columns (GEC). The expressions for stress, displacement, and hoop force of the geosynthetic, as well as stress ratio and improvement factor of the GEC composite foundation, are derived in detail. To validate the current analysis, a comparison with the solution proposed by Balaam and Booker is carried out. It is shown that the solution developed by Balaam and Booker confirms the presented solution for the case of an unreinforced column. Using the proposed method, the radial displacement and hoop force of the geosynthetic, which are affected by its stiffness, area replacement ratio and oedometric modulus ratio, are discussed. The results indicate that the main function of the geosynthetic is to provide sufficient lateral support to the columns. Decreasing the area replacement ratio is advantageous in maximising the confining effect of the geosynthetic. The oedometric modulus ratio has little influence on the confining effect provided by the geosynthetic encasement.