Experience in operating the yalta hydraulic tunnel

Conclusions

• 1. The long-term continuous operation of the tunnel shows that the main technical and economic decisions and organizational measures made during its design and construction were well-founded. The 7.3-km-long tunnel was constructed from two portal faces within 4 short years under complex geological and hydrogeological conditions with a considerable savings of the then scarce construction materials — reinforcement steel and cement.

• 2. Damages in the tunnel occurred and increased gradually. Cracking in the concrete lining that formed in stretches isolated from one another reached during operation 9% of the length of the entire tunnel. Noncorrespondence of the work of the lining to the calculated scheme caused by rock pressure that developed on stretches of the tunnel driven in argillites and siltstones of the Taurian series disturbed by tectonic processes should be considered the main cause of cracking.

  Damages that formed as a result of technological origin also occurred: poor quality of the concrete, poor placement and care of the concrete mix [1], insufficient cleaning of the rock surface before applying the shotcrete, etc.

• 3. The extent of the damages and labor expenditures on their elimination could have been reduced to a considerable degree by timely and systematic engineering intervention during operation of the tunnel. The absence of standards regulating the equipping of hydraulic tunnels with monitoring and measuring apparatus and procedure of observations of the condition of the structures is a significant cause of the unsatisfactory operation of the tunnel.