[SSS17-P19] Frictional Properties and Microstructures of Main Fault Gouge of Mont Terri Rock Laboratory, Switzerland
Keywords:friction experiment, Mont Terri Rock Laboratory, friction coefficient, back scattered electron image
Main experimental results are summarized as follows.
1) Mud rocks in Mont Terri drill holes (BFS-1, BFS-2) have the following ranges of steady-state or nearly steady-state friction coefficient μss: μss (wet): mostly 0.1~0.3, μss (dry): mostly 0.5~0.7
Dry gouges have about twice as large friction coefficients than wet gouges.
2) However, fault rock (37.3 m, BFS-1) with scary fabric has: μss (wet): 0.50~0.77, μss (dry): 0.45~0.78 (no difference between the two) This is probably because the clay contents of this rock is less (~ 33 %) than those in other rocks (67~73 %).
3) Initial peak friction coefficient μp is more or less on the same order of magnitudes as μss although μp can increase with increasing contact time and cementation in natural environments.
4) Deformed gouges are characterized by well-developed slip zones adjacent to the rotary and stationary pistons, accompanied by slickenside surfaces with clear striations. Those slickenside surfaces are similar to those developed in the drill core samples used in our experiments.
5) Slip zones are unclear in deformed fault rock from 37.3 m (BFS-1), and probably slickenside surfaces form easily in clayey mudrocks.