Modeling the Pressuremeter Test by FEM × DEM Approach

In geotechnical engineering, site investigation and soil properties determination are important tasks. For this purpose, several approaches have been developed so far. Among them, the pressuremeter is one of the most essential testing processes. This test is useful and widely applied for the estimation of soil and weak rock characteristics. Besides in-situ and/or laboratory experiment works, numerical attempts have been also developed to correctly simulate and predict the behavior of pressuremeter test made of granular soil. This is usually done by using finite element method (FEM) with (non-)associated plastic constitutive law or pure discrete element method (DEM). However, both methods have some drawbacks. First, describing the discrete nature of granular soil is not simple even with advanced constitutive law. Second, it seems a great challenge for DEM when accounting for a large number of real-grain sizes in a single simulation. To overcome these limitations, in this paper, we use multi-scale modeling, intimately combining FEM and DEM to capture the mechanical behavior of granular soil during pressuremeter test. The simulation consists of macro-discretization by finite element method and a discrete element method (DEM)-based constitutive model. To define this new constitutive model, a volume element (VE) composed of 2D-circular particles is used. The VE is then compressed to isotropic stress condition before performing the pressuremeter. Thanks to the multi-scale results, macro–micro-behaviors have been analyzed, providing micromechanics insight into macroscopic behavior of the process. The obtained results revealed that several microscopic parameters controlled and are the origin of granular soil behavior.