Analysis on Loose Circle of Surrounding Rock of Large Deformation Soft-Rock Tunnel

Table 1

Representative classification standards for large deformation of soft rocks in China.

Experts and scholars	Grade	Classification index
		(MPa)		(cm)	(%)
China railway erju construction [31]	I	5∼10	0.33∼0.2	—	4∼7
	II	10∼15	0.2∼0.125	—	7∼10
	III	>15	<0.125	—	>10
Xu Linsheng et al. [31]	I	—	—	15∼30	1.5∼3
	II	—	—	30∼50	3∼5
	III	—	—	>50	>5
Zhang Zhidao [31]	I	—	—	—	3∼6
	II	—	—	—	6∼10
	III	—	—	—	>10
Liu Zhichun et al. [31]	I	5∼10	0.5∼0.25	—	3∼5
	II	10∼15	0.25∼0.15	—	5∼8
	III	>15	<0.15	—	>8
Li Guoliang et al. [31]	I	—	0.25∼0.15	—	1.5∼3
	II	—	0.15∼0.1	—	3∼5
	III	—	<0.1	—	>5