Experimental Research and Numerical Simulation on Grouting Quality of Shield Tunnel Based on Impact Echo Method

Table 5

Comparison of peak frequency between finite element simulation and theoretical calculation.

Model number	(Hz)	(Hz)	(Hz)
SG-A-DE	6104 (6271) −2.7%	5127 (4908) 4.5%	Not obvious (3256)
SG-A-ND	6104 (6271) −2.7%	—	2930 (3256) −10.0%
SG-B-DE	6104 (6271) −2.7%	4639 (5311) −12.7%	3418 (3413) 0.1%
SG-B-ND	6348 (6271) 2.1%	—	3662 (3413) 7.3%
SG-C-DE	6348 (6271) 2.1%	4883 (5489) −11.0%	3662 (4253) −13.9%
SG-C-ND	6104 (6271) −2.7%	—	4639 (4253) −13.9%

Note: content in ( ) is theoretical results; content in bold is percentage difference between finite element simulated results and theoretical results.