We present an experimental study of identification and analysis of the collapse phenomenon in granular media, using a sample made of glass beads. The collapse potential of a soil depends on several parameters such as liquid limit, matric suction, dry apparent density, initial water content and the amount of small particles. In this study, we investigate the liquid effect during the wetting process, without external mechanical stress. Experimental tests at different initial water contents were made for different grain sizes. The equipment used is a triaxial device for unsaturated soils, instrumented with local axial and radial displacement sensors. The experimental results determined a critical water content of collapse, as well as the influence of initial water content, matric suction and grain size.