Therefore, a large-scale collapse is sometimes treated by consolidation grouting of the loose collapse body above the tunnel within a certain thickness range .
However, after a loose collapse body of a certain thickness above the tunnel is subjected to consolidation grouting, there is a cavity above the consolidation layer formed in the process.
Based on the actual conditions of the large-scale collapse, a support system was employed consisting of the pipe umbrella arch and steel grid arch, combined with a consolidation grouting treatment of the loose collapse body in the collapse cavity.
In the spring, when the lake was full, the water pressure revealed leaks in two discrete sections of the tunnel so consolidation grouting was specified using microfine cement.
This installation will allow for future consolidation grouting at the conclusion of the civil works.