Using NDT for thickness measurement of shotcrete rock support systems in underground mines

Shotcrete is quickly becoming the economical material of choice for rock support systems in underground mines throughout Canada. Although shotcrete technology has gained acceptance in the mining industry, there are some problems which have emerged with respect to quality assessment and thickness measurement of the liner. This paper presents recent tests performed with a miniature seismic reflection device developed primarily for thickness measurement of this heterogeneous liner. Work was performed on site in an underground mine in Ontario, Canada. This paper also presents the results from laboratory tests performed on fiber reinforced an non reinforced shotcrete panels which were used to asses the P-wave velocity in both materials. The results of these tests were used in a second on site investigation. The NDT thickness measurements showed good agreement with the results obtained by mine personnel with conventional methods.