Page 51

2017SpringShotcreteEMag

LINING A SHAFT IN ONE DAY The upper 700 ft (210 m) was in questionable ground, so it was decided to raise a smaller 10 ft (3 m) diameter bore to shotcrete the shaft and then excavate from the top down. The day after the bore machine was removed, crews lowered a camera down and marked where the shotcrete was needed—a total of 240 ft (70 m) in various areas. “At 11 a.m. we started lining a flash coat, top to bottom,” says Kristian Loevlie, President, Shotcrete Technologies, Inc. “We then lined 3 in. (75 mm) of shotcrete where needed and by 6 p.m. the same day, we had completed the shaft lining.” A total of 38 yd3 (29 m3) was in place. The company made PAN AMERICAN SILVER its shaft lining concrete mixture on-site using local materials and the on-site batch plant. “We used 900 ft (270 m) of hose to keep everything flowing smoothly,” Loevlie adds. There was no noticeable rebound and this structural shotcrete reached 3000 psi (20 MPa) in 24 hours and 7000 psi (50 MPa) in 14 days. References Morgan, D.R.; Loevlie, K.; Kwong, N.; and Chan, A., 2010, “Centrifugal Sprayed Concrete for Lining Horizontal Pipes, Culverts, and Vertical Shafts,” 3rd International Conference on Engineering Developments in Shotcrete, New Zealand, Mar. 15-17, 7 pp. Fig. 3: Shaft lining with the spider Fig. 4: Crane over the shaft Norwegian-born Kristian Loevlie, Cofounder and Owner of Shotcrete Technologies, Inc. (STI), is one of the world’s leading experts in wet-mix shotcreting. His technical expertise, including specifications, mixture designs, logistics, equipment and system design, and training has provided STI a firm foundation in the shotcrete world with the cutting edge of new technology and techniques. Fig. 1: Hoses before lining Fig. 2: Lowering the egg into shaft www.shotcrete.org Spring 2017 | Shotcrete 49


2017SpringShotcreteEMag
To see the actual publication please follow the link above