Corrosion Investigation of Rock Anchors Served over 10 Years in Underground Powerhouse of a Hydropower Station

Table 10

Corrosion ratings of anchor head structure.

Position	Quantity (pcs.)	Corrosion degree rating
		0	1	2	3	4
Upstream sidewall	27	5	1	11	0	10
Downstream sidewall	28	5	2	12	0	9
Left-end wall	8	3	0	5	0	0
Right-end wall	10	2	1	4	1	2
Arch crown	81	3	0	46	16	16
Total	154	18	4	78	17	37
Percent	100.00%	11.69%	2.60%	50.65%	11.04%	24.03%