Application of Impact Imaging Method on Nondestructive Detection of Void Defects in Sandwich-Structured Immersed Tunnel

Table 6

Analysis of errors between the calculated and the measured void heights at position No.1.

No.	Impact response intensity	Calculation void height (mm)	Measured void height (mm)	Error (mm)
1	1.19	0	0	0
2	1.54	0	0	0
3	1.04	0	0	0
4	4.02	5.07	5.5	−0.42
5	5.12	6.63	6	0.63
6	5.57	7.23	7	0.23
7	5.86	7.61	7	0.61
8	6.27	8.12	7	1.12
9	8.42	10.57	11	−0.43
10	10.73	12.77	16	−3.22
11	14.51	15.60	13	2.60