Safe Blast Design for Efficient and Sustainable Underwater Excavation: Art Meets Science!

Abstract Most of the dredging work associated with harbor, port, channel deepening, and other related operation requires underwater blasting due to the characteristics of material being dredged / moved. Underwater blasting is typically used to remove rocks for deepen harbours and channels, creating channels and levees, installing conduits, and other more specialised blasting operations that shall be completed below sea. Usually, such dredging work occurs in deep-water of varying between 16–20m in order to remove just few meters of rocks. Hence, this type of blasting activity needs high level of skill and familiarity than equivalent activities carried out above the surface of water because of aqueous layer over the its rock. Therefore, the factors such as selection of drilling parameters and drilling equipment, selection of appropriate explosives and accessories, usage of correct powder factor, determination of safe explosive charges per delay and selection of suitable personnel are studied carefully for accomplishing the successful underwater blasting operations. In addition to the above, the system shall also address the proper design for the underwater blasts to excavate the rock to the required depth keeping in view the permissible allowances of minimum and maximum depth and fragment size required. While adopting underwater blasts, adequate safety measures are also defined for safety of men, other vessels in the blasting zone and structures from blasting vibrations. Here, the authors broadly outline their approach with respect to underwater blasting using the existing blasting technology, with a case study.