RESEARCH PAPER Discrete element simulation of geogrid-stabilised soil Michael Stahl • Heinz Konietzky • Lothar te Kamp • Hein Jas Received: 2 November 2012 / Accepted: 5 July 2013 Ó Springer-Verlag Berlin Heidelberg 2013 Abstract A particle-based numerical simulation procedure is presented for the generation and calibration of geogrid- stabilised soil on the basis of experimental data. The paper describes how to simulate a biaxial geogrid depending on a specific particle and parallel bond model. Numerical and experimental pull-out tests have been performed to reproduce the pull-out force–strain behaviour of a biaxial geogrid specimen embedded in granular material under special con- sideration of the grain-size distribution, initial relative den- sity, normal stress state as well as sample installation. Model analysis of soil mobilisation and geogrid deformation is presented to understand the significance of the interlocking effect as key mechanism for soil stabilisation. The procedure can be used for further investigations of the influence and effects of soil stabilisation depending on the significant properties of the interacting components (soils and geogrids). Keywords Calibration procedure  Discrete element method (DEM)  Granular soil  Geogrid  Interlocking effect  Laboratory test  Pull-out test 1 Introduction In the fields of ground and road engineering, the use and acceptance of geosynthetics and geogrids increased over the past 30 years. Geogrids are a specific synthetic grid, primarily used to improve the mechanical characteristics of granular soils in terms of tensile properties. The stiff ribs and junctions allow the soil particles to penetrate into the apertures during the compaction process, whereby the grains are being confined within the boundaries of the apertures (interlocking effect). In practice, several design methods with geogrids are in use, but all of them are more or less empirical and none incorporates the interaction between soil and geogrid at the micro-level. The discrete element method-based Particle Flow Code PFC 3D , which simulates the mechanical behaviour of a system comprised of rigid spherical particles and wall elements, offers good chances to model the behaviour of the soil–geogrid interaction in a realistic manner. For this purpose, mainly a realistic soil model is necessary in which the simulated grains have the ability to penetrate into the apertures of a geogrid model in a proper manner. A par- ticle-based numerical simulation procedure in PFC 3D was presented by Stahl and Konietzky [16], which allows to generate stiff granular material (ballast or gravel) using the clump logic under special consideration of grain shape, grain size and relative density. This paper presents a procedure to simulate and ana- lyse the pull-out behaviour of a biaxial geogrid embed- ded in granular material using PFC 3D based on the specifications and results of adequate laboratory tests under special consideration of the grain-size distribution, initial relative density, normal stress state as well as sample installation. M. Stahl (&) Am Muehlenhaus 1, 47906 Kempen, Germany e-mail: m.stahl.geotechnik@gmx.de H. Konietzky Geotechnical Institute, TU Bergakademie Freiberg, Freiberg, Germany e-mail: heinz.konietzky@ifgt.tu-freiberg.de L. te Kamp ITASCA Consultants GmbH, Gelsenkirchen, Germany e-mail: Ltekamp@itasca.de H. Jas 7asConsult BV, Oostvoorne, The Netherlands e-mail: hein@7asconsult.nl 123 Acta Geotechnica DOI 10.1007/s11440-013-0265-0