Test on the Influence of Geometric Parameters of an Annular Trench on the Vibration Isolation Area

Table 2

Particle composition and related indices of the back-filled sand.

Soil particle group name	Particle size range (mm)	Content (%)	Particle composition index
Pebble	>60	—	d60	0.368
Gravel	60∼20	—
	20∼5	0.7	d30	0.289
	5∼2	2.6
Sand	2∼0.5	11.1	d10	0.127
	0.5∼0.25	63.7
	0.25∼0.075	16.0	Cu	2.9
Silt	0.075∼0.05	0.5
	0.05∼0.01	0.8	Cc	1.9
	0.01∼0.005	0.4
Clay	0.005∼0.002	>0.0