As shown above, the shotcrete thickness is determined point by point, and then the thickness is contoured; the density of the mesh used for thickness calculations may be chosen based on the client’s specifications.

A rolled-out view of the shotcrete intrados may also be obtained. In the figures, the red color indicates a thickness smaller than 2 cm (0.8 in), the white color indicates a thickness between 2 and 5 cm (0.8 and 2 in), and the green color indicates a thickness greater than 5 cm, 2 in (design thickness in this case). The thickness is highly variable, and smaller than 5 cm (2 in) over a large portion of the shotcreted area. This example indicates that the thickness determined by coring may be quite aleatory because the results may vary significantly by just moving the coring machine by a few centimeters (inches) to the left or to the right, or by just orienting the coring machine at a slightly different angle.

This figure illustrates the level of detail in the determination of the shotcrete thickness and of the irregular shotcrete surface. Also, notice that the bolt is green, which correctly indicates a distance of more than 5 cm (2 in) with respect to the rock surface.


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