Issue 41

L. Zhang et alii, Frattura ed Integrità Strutturale, 41 (2017) 356-368; DOI: 10.3221/IGF-ESIS.41.47 365 Figure 7 : 12h traditional support plastic zone. Figure 8 : 12h new support plastic zone. Figure 9 : 1d traditional support plastic zone. Figure 10 : 1d new support plastic zone. Figure 11 : 3d traditional support plastic zone. Figure 12 : 3d new support plastic zone. E NGINEERING APPLICATION Project Overview he field test is conducted on the developed new liquid accelerator in Changgang tunnel of Fushou Highway. This tunnel is class IV surrounding rock; the strength grade of shotcrete is designed to C25 and the shotcrete layer depth to 25 cm. The field shotcrete adopts Hong Xing-1 powdered accelerator; the dry jet machine adopts 7 m 3 ; the actual amount of sprayed concrete per hour is about 5 m 3 . The dry powdered accelerator has the actual dosage reaching 10%, about 30% resilience, and large amount of dust during spraying. Fig. 13 shows the field dry-mix shotcrete. T