[DX-P-01] Rupture process of rock mass including weak zones using three-dimensional discrete element method (3D-DEM)
Experiments with three-dimensional (3D) analog and numerical rock mass models have been tested to clarify the geological evolution of active faults and the occurrence of earthquakes. The previous studies modelled a simple crustal structure. However, the active fault distributions are complex and possibly affect the occurrence of earthquakes. For example, a main shock of a large earthquake often occurred near the bend of the fault zone (e.g., the 1995 Hyogo-ken Nanbu Earthquake in Japan). The relationship between rupture formation and earthquake occurrence around the complex active faults has not been discussed in previous laboratory and numerical experiments.
In this study, we investigated how the rock mass including weak zones, which using numerical simulation. It has greater advantages than the laboratory experiments; the numerical simulation allows us to observe the internal deformations of rock mass. In this study, we simulated the strike-slip fault motion with a small-scale rock mass model using the 3D distinct element method (DEM). Various rock mass models were tested in this simulation. For example, we test whether the shape of the weak zone has a significant effect on the occurrence of an earthquake. The processes of ruptures propagations in two contrastive models are compared. Both models have a weak zone commonly; one model is characterized as a continuous bending weak zone, and another has a discontinuity (gap) of weak zone at the bending. As a result, it was found that the rupture process of the discontinuous model is similar to the main shock and aftershock sequence often observed such as at the 1995 Hyogo-ken Nanbu earthquake. Thus, the 3D-DEM simulation is effective to understand the rupture process along faults at earthquakes.
In this study, we investigated how the rock mass including weak zones, which using numerical simulation. It has greater advantages than the laboratory experiments; the numerical simulation allows us to observe the internal deformations of rock mass. In this study, we simulated the strike-slip fault motion with a small-scale rock mass model using the 3D distinct element method (DEM). Various rock mass models were tested in this simulation. For example, we test whether the shape of the weak zone has a significant effect on the occurrence of an earthquake. The processes of ruptures propagations in two contrastive models are compared. Both models have a weak zone commonly; one model is characterized as a continuous bending weak zone, and another has a discontinuity (gap) of weak zone at the bending. As a result, it was found that the rupture process of the discontinuous model is similar to the main shock and aftershock sequence often observed such as at the 1995 Hyogo-ken Nanbu earthquake. Thus, the 3D-DEM simulation is effective to understand the rupture process along faults at earthquakes.
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