Experimental Study on the Transition between Static and Kinetic Frictions of Steel/Shale Pairs

Table 1

Values of the surface morphology parameters of the shale specimen.

Roughness parameter ()	Shale 1#	Shale 2#	Shale 3#
(arithmetic surface roughness value)	0.491	0.740	0.421
(root-mean-square roughness)	0.693	0.944	0.622
(core roughness depth)	1.011	1.667	0.970
(reduced peak height)	0.200	0.399	0.238
(reduced valley depth)	1.307	1.673	1.266