I put implementation not at the bottom of the page with adehsive models (http://woodem.eu/doc/theory/contact/adhesive.html
). The current adhesive model has some implementation limitations (most notably, that surface energy and the alpha parameter are not per-particle, but the same in the whole simulation) which could be overcome easily. This type of adhesive models is suitable for powder-like materials, however, not really for rocks.
For rock, you might check out the concrete model http://woodem.eu/doc/theory/contact/concrete.html
(which is a type of fragile model with many features like rate-dependence, calibration procedures and strong connection to continuum mechanics), but it was ported from Yade only recently, and altohugh the model itself is very well tested, the port has not been yet (again, something which could be done if you need it).
Finally, a brand new cohesive model (designed for ice, but it will work for rock as well, once calibrated) is in the works: http://woodem.eu/doc/theory/contact/ice.html
(should be ready within a few weeks).
Let me know if you want to try out the concrete model, I would test the implementation. If you want the ice model, wait two or three weeks before it is ready for its prime time.