Micromechanical investigation of grouting in soils

Grouting and jet grouting are geotechnical consolidation techniques commonly employed to improve the mechanical behaviour of soils. Although these techniques are common, the micromechanical processes taking place at the local level are not yet totally understood and modelled. In this work, such a problem has been approached from a micromechanical perspective via the discrete element method by considering the local interaction among soil grains and pseudo-fluid particles. Homogeneous representative elementary volumes of a virtual analogue of silica sand have been first generated and tiny rigid frictionless particles have been subsequently injected through them, to simulate the grouting in granular materials. Various injection pressures, initial soil pressures and initial soil densities have been considered. The different diffusion patterns, the flow rate, the consequent increase in local stresses and the consequent reduction in local porosity have been discussed. To overcome the DEM computational restrictions and to speed up the injection simulations, a novel procedure based on the replication of pre-equilibrated cells has been adapted for both the initialization and injection phase. Finally, a qualitative laboratory-scale pressure grouting test has been reproduced to validate the results.