A New Approach of Waveform Interpretation Applied in Nondestructive Testing of Defects in Rock Bolts Based on Mode Identification

Table 4

Comparison of the velocities calculated by theoretical, numerical, and experimental method.

Rock bolt	Main modes		Theoretical velocity,; (kg/m^3)	Numerical velocity,; (kg/m^3)	Experimental velocity,; (kg/m^3)	Error
						＆	＆
Full rock bolt	Mode	End echo	1.75	1.73	1.74	0.57%	0.57%
	Mode	End echo	2.40	2.36	2.33	3.00%	1.29%
Rock bolt; with grout loss	Mode	Defect echo	1.75	1.74	1.73	1.16%	0.58%
		End echo	1.75	1.72	1.76	0.57%	2.27%
	Mode	Defect echo	2.40	2.47	2.54	5.51%	2.76%
		End echo	2.40	2.29	2.35	2.13%	2.55%