Use of crack-resistant linings of hydraulic tunnels with consolidation grouting of the rock

Conclusions

• 1. The use in pressure tunnels of crack-resistant prestressed structures (lining—rock) made by the method of high-pressure grouting of the rock leads to a reduction of materials consumption of the linings, decrease of seepage leaks of water from the tunnel and, as a consequence, of production losses of the hydrostation.

• 2. It is most expedient to use the indicated structures in high-pressure tunnels with circular linings with a diameter of not more than 5–6 m located in rocks in which consolidation grouting is effective.

• 3. Strict observance of the prescribed technology is necessary with mandatory group grouting of all holes in the perimeter and, as far as possible, of the whole tunnel section under the maximum possible pressure, which is determined from the condition of stability of the lining and characteristics of the injection equipment being used.

• 4. The use of such structures requires the conduction of combined (laboratory and on-site) investigations for the purpose of selecting the optimal compositions of the injection grouts and injection parameters (pressure, number and depth of holes, number of injection cycles, etc.) and evaluating the effectiveness of grouting under the given conditions from the viewpoint of creating prestressing in the lining and enclosing rock mass.