Critical Coulomb Extensional Wedge. Particles within the deforming mass have a coefficient of interparticle friction of 0.81; the friction coefficient between internal particles and the rigid row of balls at the base is 0.51, defining a weak detachment surface. As the wedge extends, the layered mass fails along discrete faults, and by distributed flow of particles near the toe. The wedge forms a "critical taper" at the toe; subsequent extension is accommodated by stable sliding of the mass down the detachment with little internal deformation. (Ignore those balls at the bottom of the picture; because I use periodic boundaries, they belong at the top of the failing mass.)
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