Numerical investigation of the particle skeleton of widely graded soils prone to suffusion

Winkler, P. and Jentsch, H. and Salehi Sadaghiani, M. and Witt, K. (2016) Numerical investigation of the particle skeleton of widely graded soils prone to suffusion. In: ICSE 2016 (8th International Conference on Scour and Erosion), 12-15 September 2016, Oxford, UK.

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Abstract

The soil structure affects directly the capability of distributing and transmitting forces between its particles. Thus, the particle arrangement dictates the performance of soil under hydraulic and dynamic loads. This paper describes an analysis method in which the skeletal force chains of the particle assembly (packing) can be identified based on Discrete-Element-Method (DEM) modelling. For the simulations the software LIGGGHTS is used. A widely graded particle size distribution (PSD) is investigated to find correlations between PSD and the micromechanical properties of the particle assemblies. These PSD is based on common internal stability criteria prone to suffusion. The different roles of fractions of the PSD in packings and the force chains under specified load are analysed. Therefor a packing is generated with the Modified-Force-Biased-Algorithm (MFBA). A method based on the bimodality of widely graded PSDs is proposed to differentiate the soil skeleton and the fill of packings of such a PSD. Particle contact number and contact forces are evaluated to identify the amount of loose particles, which are potentially mobile particles. The influence of the packing homogeneity on its skeleton is also addressed. The described method provides a better understanding of the soil structure as well as of internally stability of widely graded soil.

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