Experimental and analytical study on soilbag and encased sand columns in loose sand

Abstract

It has been shown that wrapping granular soil with geotextile significantly increases its bearing capacity. This finding, recently, has extended the use of soilbags to construct permanent structures. This paper investigates the compressive behavior of a new geo- column called the soilbag column. Several compression tests were performed for both end-bearing and floating columns with different diameters and lengths in a testing tank filled with loose sand. To compare the effectiveness of this method with other common techniques of soil improvement, the compressive behavior of encased sand columns was also studied. In both scenarios, induced additional confining pressure provided by the encasement is the most important factor in increasing the bearing capacity. The results indicated that the soilbag columns provide much stiffer compression behavior than the encased sand columns. Compared to an encased sand column, the superiority of using a soilbag column is more evident for the end-bearing type. The values of bearing capacity of the physically modeled encased sand columns agreed well with the values estimated by an analytical approach using cavity expansion theory. Besides, an analytical approach developed to predict the stress-strain response of the soilbags under the uniaxial compression test.