Study of Deformation Behaviors and Mechanical Properties of Central Diaphragm in a Large-Span Loess Tunnel by the Upper Bench CD Method

Table 2

The observation frequency in Wangcun tunnel.

Serial number	Item	Instrument	Observation frequency
1	Horizontal convergence	Total station	1–15 days	1-2 times/day
			16 days—1 month	1 time/day
			After 1 month	1-2 times/week
2	Crown settlement	Total station	1–15 days	1-2 times/day
			16 days—1 month	1 time/day
			After 1 month	1-2 times/week