Abstract:

It has been realized that, the force chain is crucial to the fundamentals of granular materials. The photoelastic granular material of bi-disperse discs was employed to investigate the evolution of the packing and the force chain when subject to 2D direct shearing. Photoelastic experiments of granular materials were employed for the first time in the study of force chains of granular materials in China. Experimental techniques were dealt with including the development of a photoelastic direct shear apparatus as well as the manufacturing and annealing of Polycarbonate discs. The photoelastic direct shear experiments results as obtained were processed using the digital image processing methods, in which the average color gradient method was introduced to extract the force chain information developed. Anisotropy of the packing of the bi-disperse granular material was observed. The equally important was the localization of intermediate strong force chains based on the statistical analysis.

Key words: granular materials, photoelastic experiment, force chain, packing, anisotropy, digital image processing.