Digital image based numerical micromechanics of geocomposites with application to chemical grouting

The presented paper describes procedures of numerical upscaling and experience with X-ray CT based finite element (FEM) analysis of properties of geocomposites. The upscaling technique is used for obtaining the macro-level response of material by loading test (representative) volumes with described micro-level structure. The application is focused on geocomposites arising from chemical grouting of coal substances. The obtained (homogenized) macro-level properties serve for solving stability problems by numerical modeling in geotechnical engineering. The paper touches several interacting topics - numerical upscaling and understanding to its results; application of X-ray computed tomography (CT) for visualization of structure of geomaterials; processing the digital image data for constructing FEM models of test volumes; numerical testing of digitalized samples for obtaining homogenized properties and clearing up sensitivity to changes in local material properties, micro-level structure and FE mesh; validation of numerical results by comparison with laboratory testing of samples; use of identification technique for refining the local material properties and calibration of the upscaling procedure.