Risk Assessment Study on Mechanical Connecting Aisle Construction in the Bohai Mudstone Stratum with High Water Pressure

Table 2

Interval main strata.

The layer number	Geotechnical name	Basic mass grade of rock mass
⑪	Silty clay and medium-coarse sand	Grades II~III
⑫	Medium coarse sand and 1 silty clay	Grades II~III
⑯	8-2 tuff (sandy fissure rock), strongly weathered volcanic breccia, and 13 argillaceous siltstone	V. Class
⑰	11 moderately weathered volcanic breccia, 8-2 tuff (sandy fissure), 13 moderately weathered argillaceous siltstone, and 11-2 moderately weathered volcanic breccia (massive fissure)	V. Class
⑱	Mildly weathered tuff, 8-3 breezy tuff (joint development zone)	Level IV