Fast driving of heading no. 10 of the power tunnel for the Ingursk hydroelectric plant

Abstract

1. In the excavation of tunnels having large cross sections, the utilization of drill carriages equipped with BU-1 drifters is a progressive measure, which brings about increased rates of driving, and improvement of all the economic indexes. The drill carriage permits achieving considerable accuracy in the blast-hole drilling, which along with other measures, results in reduction of rock fracturing and excess concrete placement. It permits also combining the blast-hole drilling operations and the installation of the rock bolts and makes substantially easier the rock scaling and loading of the blast holes. In the design of drill carriages, allowance should be made for space under them, for passage of dump trucks having the largest possible loading capacity. 2. The selection of the optimum schedule for the drilling-blasting work is a basic requirement for obtaining a large advance per round, a smooth excavation, and a reduction in the fracturing. Deeper blast holes contribute to sharp reductions in the time for the accessory operations in tunnelling. 3. Rock bolts, as compared with steel rib supports, proved to be a progressive and economical method of support, which requires less time for its installation, and makes possible combining the operations of supporting the rock and drilling the holes. Rock bolts are a dependable type of support, which should be recommended in the pertinent geological specifications.