Special page

Shear bands

Under high pressure rocks deform according to Mohr Coulomb plasticity and so the deformations generally localize into shear bands (if the angle of friction is different from the angle of dilatancy which is usually the case).


The figure shows a 2d system under horizontal compression and vertical extension simulated with Alex Poliakov. The colors show the local shear rate (red = high rate). For more details see our paper published in Geophys. Res. Lett. 21, 2143-2146 (1994)


The network is fractal and its dimension agrees well with that of that of shear bands on granite which Alex and myself photographed in the Pyrenees as has been shown in our paper in Fractals 2 , 567-581 (1994)


One of the big questions about shear bands is to understand their finite width. With Bertrand Francois and Frederic Lacombe we proposed a model that can give an estimate on the width in units of grain diameters based on the combinatorics of stress paths. We also did a simple two dimensional experiment to verify the predicted probability functions. All this is published in a paper published in Phys. Rev. E, Vol. 65, 031311 (2002)