Experimental Study on Stiffness Softening of Soil-Rock Mixture Backfill under Metro Train Cyclic Load

Table 3

Impact of various factors on the softening index.

Rock content (%)	Consolidation stress (kPa)	Consolidation degree	Stability softening index
20	100	0.98	0.78
		0.90	0.71
		0.80	0.66
	200	0.98	0.70
		0.90	0.65
		0.80	0.54
	400	0.98	0.66
		0.90	0.60
		0.80	<0.40 (breaking)
10	200	0.98	0.47
40	200	0.98	2.20 (hardening)