Abstract
Earthquakes happen with frictional sliding, by releasing all the stresses accumulated in the prestressed surrounding medium. The geological fault gouge, coming from the wear of previous slips, acts on friction stability and plays a key role in this sudden energy release. A large part of slip mechanisms are influenced, if not controlled, by the characteristics and environment of this tribological “third body”. A 2D granular fault (mm scale) is implemented with Discrete Element Modelling (DEM). A displacement-driven model with dry contact is studied to observe kinematics and properties of the slipping zone. Increasing the length of the granular media increases the slip needed to weaken the friction from friction peak to steadystate. Low-angle Riedel shear bands are mostly observed. Their number increases with the inter-particle friction coefficient, which also influences shear bands formation in their orientation angle (higher friction leads to higher angle with the main slip direction).
Highlights
During earthquakes, frictional sliding releases all stresses accumulated in the pre-stressed surrounding medium
This work is seen as the first step towards simulations considering a mixture between angular grains surrounded by polygonal cells representing a matrix of fines
This paper only focuses on this matrix and aims to present the shearing and slip behaviour of a granular medium composed only by conforming polygonal cells
Summary
Frictional sliding releases all stresses accumulated in the pre-stressed surrounding medium. Analogies with the concept of tribological triplet [1] are straightforward: between the two first bodies (i.e. rock walls constituting the fracture), the geological third body is composed by the granular material coming from the wear of previous slips. The DEM code MELODY 2D [5] is used to simulate a mature fault with cemented material between rock particles To simulate this cement, we first realized a study with angular and faceted grains with cohesion law between particles [6]. We first realized a study with angular and faceted grains with cohesion law between particles [6] Another approach is used here to model this cement with a matrix created by an assembly of small polygonal cells. This paper only focuses on this matrix and aims to present the shearing and slip behaviour of a granular medium composed only by conforming polygonal cells
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