Experience in drilling and blasting operations to Loosen underwater rocks

Conclusions

1.With the large powder factor needed for good crushing of the rock the cost of drilling and blasting operations increased somewhat (by about 7–10%, i.e., by 0.7–1.0 ruble/m³). However, in this case the cost of removal of the loosened rock decreases markedly (by about 33%, from 6 to 4 rubles/m³), as a result of which the overall cost of underwater rock-removal works decreases. Therefore crushing of rock underwater is performed more economically with an increased powder factor. 2.The high indices obtained with respect to labor productivity and cost of drilling and blasting operations can be improved mainly by more productive drills (instead of type BMK), since drilling occupies about 60% in the total labor intensity of the operations. 3.The performance of drilling and blasting operations from the FDR has many advantages compared with the performance of operations from the usual floating means.

The technicoeconomic indices can be improved by the simultaneous use of not two but three and more drills (by increasing the area of the drilling platform). In this case the indices of performing operations from the FDR not only with respect to labor productivity but also with respect to cost will be better than when performing operations from the ice cover. Furthermore, blasting in the presence of an ice cover inflicts greater damage on fishery than in an open water area. Therefore, unless there are special circumstances, the maximum amount of drilling and blasting operations should be performed in the absence of an ice cover from the FDR.