Tomoyuki SAWA

Numerical Modeling of Fracture Behavior of Geomaterials Based on Peridynamics-DEM

Yutaka FUKUMOTO

In recent years, landslides (mudslides, landslides, and cliff collapses) caused by typhoons and earthquakes have become more frequent and severe, and have become a major social problem. Under these circumstances, effective prediction and countermeasures against landslides are urgent issues for land use in Japan. However, scientific elucidation of ground failure phenomena such as embankment failure, which is a progressive failure, is still insufficient. To predict ground failure phenomena, it is necessary to understand the onset and growth process of slip surfaces. Considering a slip surface as a surface where objects are physically separated, the initiation and growth of a slip surface can be regarded as the initiation and growth of a crack from the viewpoint of fracture mechanics. In this study, a numerical model is proposed to understand the process of crack initiation and growth in ground failure phenomena. First, uniaxial compression simulations of compacted clay were performed and compared with experimental results from Ishikawa National College of Technology. Third, a multi-particle crushing simulation was performed using the model studied above. The results show that the proposed coupled Peridynamics-DEM model can calculate the cycle of geomaterial deformation, crack initiation, and fracture. Replicated analyses of uniaxial compression and compression-tension tests on specimens with initial cracks were performed on compacted clay as a geomaterial, and the same parameters were used to obtain compressive and tensile strengths and crack propagation that corresponds to the experiments. Furthermore, by introducing a modified PMB model that softens the bond between the calculation points, the nonlinear stress-strain relationship seen in experimental results for compacted clay was obtained. Crushing simulations of multiple objects allowed analysis with line elements and arbitrarily shaped objects. In the future, we believe that the model can be improved by reducing the loading surface in the compression-rupture tensile test and by introducing image analysis to measure the strain distribution before crack initiation. In addition, it is necessary to examine the validity of the fracture simulation by conducting experiments with multiple specimens stacked on top of each other. With the above improvements, it is possible to eventually expand the analysis to the scale of soil structures such as road embankments and river embankments.