Study the geomechanical properties of material from the waste disposal center

Abstract

The mechanical behaviour of porous media (clay, rocks,...) is related to the ability of interstitial fluid (liquid and gas) to flow. Indeed, in order to preserve the environment in general and water resources in particular, awareness is developing in Algeria to improve the dumps, especially the transfer of toxic fluids (leachates). The water transfer in porous media affects several areas of application related to geotechnical environmental (waste storage, infiltration of pollutants, contamination of groundwater,...), hence the need for experimental characterization on solicitations paths.

Throughout the work, we focused on the characterization of material designed as an impenetrable barrier of waste disposal center and its behavior on different solicitations paths. We chose a fine material to characterize in laboratory in order to study its behaviour. This necessitates carrying out tests to identify which state that the material is a little plastic clay (trend toward a sandy loam). Other mechanical tests were performed on oedometer path and shear strength in contact with water and with leachates. Through these oedometric tests we have defined the intrinsic material parameters namely the coefficients of compressibility and swelling, and studied the influence of leachates on these parameters. The results show that the toxic fluid affects the compressibility of the material used.

On the same paths, using a permeameter dependent variable, we determined the permeability of the material. In the presence of leachate, the permeability coefficient measured increases, and conversely it decreases as the stress increases. The shear strength tests have allowed us to determine the parameters of plasticity, such as cohesion and angle of friction and to examine the influence of leachate on these parameters. Experimental results show that the cohesion increases in the presence of toxic fluid. However, the friction angle decreases as the leachate enters the soil.