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

Table 5

Shear wave velocity test results.

Working condition	Test hole number	Test range (m)	Lithology	(m/s)	Equivalent shear wave velocity (m/s)
Before the metro train opened	SHXK14	0∼50	Plain fill	205∼231	213
		50∼52	Sandstone	623∼1244
	SHXK15	0∼60	Plain fill	201∼225
		60∼62	Sandstone	658∼1234
13 months after the metro train opened	138-7	0∼27	Plain fill	315∼337	322
	204-6	0∼27	Plain fill	330∼348