Variation of Rock Mass Pressure during Tunnel Construction in Phyllite Stratum

Table 2

Monitoring results of rock mass pressure in YK214 + 011 section/MPa.

Monitoring positions	Before upper bench excavation		Before lower bench excavation		Before the construction of invert		Before the construction of the secondary lining		Final monitoring value
	Rock mass pressure	Ratio (%)	Rock mass pressure	Ratio (%)	Rock mass pressure	Ratio (%)	Rock mass pressure	Ratio (%)
Y0	0.034	17	0.080	39	0.174	84	0.196	95	0.206
Y1	0.063	54	0.066	57	0.060	52	0.100	86	0.116
Y2	—	—	—	—	—	—	—	—	—
Y3	0.013	25	0.015	29	0.019	37	0.052	100	0.052
Y4	0.003	3	0.033	37	0.078	88	0.089	100	0.089
Y5	—	—	0.037	40	0.012	13	0.064	69	0.093
Y6	—	—	0.046	21	0.170	76	0.223	100	0.223
Y7	—	—	—	—	—	—	0.065	155	0.042
Y8	—	—	—	—	—	—	—	—	—