Change in the state of rocks under the effect of a large-scale explosion

Conclusions

• 1. When conducting large-scale explosions, zones of different explosion effects form in the rock mass beyond the limits of the demolition contour (explosion crater). Two zones are distinguished in the mass according to the degree of effect: strong and weak. The thickness of these zones depends on the power of the charge and composition and state of the rocks before the explosion. For a 100-ton charge the thickness of the zone of strong explosion effect is about 30 m, and for a 500-ton charge 45 m. The zone of weak explosion effect has a slightly greater thickness. At the site of the Kambaraty hydrodevelopment the thickness of the zone of strong effect will apparently be close to 100 m.

• 2. Within the zone of strong effect the change in the state of the rocks is due to the formation of new fractures with a width up to 1 m (on the surface) and expansion of the existing fractures. Within the zone of weak effect the change in the state of the rocks is due to expansion of the existing large and small fractures.

• 3. The stability of underground structures depends on their distance from the charge, section, and type of support. The underground structure for the hydrodevelopment should be placed outside the zone of strong explosion effect.

• 4. Potentially unstable masses with a volume up to 30,000 m³ formed on the slopes within the demolition contour (explosion crater) following the explosion. The formation of potentially unstable masses will occur following the explosion at the site of the Kambaraty hydrodevelopment within the explosion crater and higher up the slope. This is related to the great elevation of the watershed above the crest of the future dam.