Experimental study on the behavior of sandy soil reinforced by stone columns

This paper reports the results of a series of drained and undrained triaxial tests on Chlef soil reinforced with stone columns surrounded by geotextiles. The tests are carried out on reconstituted samples having an initial density index Id =0.50 and which are subjected to an initial confining pressure of 100 kPa. In order to create stone columns that can be realized in situ, sand grains with an average diameter of 2 mm are used to manufacture the tested specimens. In addition, we used 70 and 10 mm for the length and diameter of the stone column, respectively. The test results show that, in one hand the stone columns’ presence affects significantly the soil shear strength, that increases according to the stone columns number and reduces the soil contractiveness (vertical strain), and in the other hand, it decreases the interstitial pressure. Encasement improves the effectiveness of the stone column and raises the rigidity of the reinforced soil by reinforcing the stone column with geotextiles. Furthermore, the secant modulus increases versus of the stone columns number, which is due to the inverse proportionality of this modulus to the axial strains. In addition, the internal frictions increase following a linear evolution law with the increase in the number of inclusions of reinforcements stone columns.