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Underwater drilling and blasting techniques have been developed to overcome the challenges posed by various subaquatic operations, including marine construction, oil and gas exploration, and underwater mining, demolition, dredging and excavation, seismic surveys and marine research. The drilling operation is followed by underwater blasting, which involves the creation of boreholes in submerged surfaces, such as sea beds or riverbeds. Specialized drilling equipment is utilized, which can operate in aquatic environments. To ensure efficient and reliable performance, the drilling equipment is designed to withstand the pressures and corrosive nature of seawater. Once the desired depth is reached, underwater blasting is utilized to break the rock or seabed. The primary objective of blasting is to loosen the substrate and create a cavity for subsequent operations. Safety is a crucial factor in underwater drilling and blasting operations. To safeguard personnel involved and prevent accidents during drilling and blasting activities, strict safety measures are implemented. In addition to human safety, precautions are taken to minimize the environmental impacts of underwater drilling and blasting, including measures to prevent pollution, protect marine life, and preserve the underwater ecosystem. In this article, the core elements of underwater drilling and blasting operations are outlined. Despite notable progress in this domain, the paper highlights the enduring constraints and obstacles, underscoring the need for continued investigation and understanding. [ABSTRACT FROM AUTHOR]

Burden is one of the major influencing blast design parameters which should be optimised for the extraction of narrow vein ore bodies. Numerical simulation-based approach has been used for the optimisation of burden in this paper. Different models were prepared under varying parametric conditions including width of the vein, blasthole diameter and burden. The RHT concrete constitutive model was used for the analysis of damage contour. The volume of the excavated rock along the free face (EV) was quantified from the model output in all the scenario. The study showed that EV initially increases with the increase in burden for a particular width of vein. Furthermore, EV starts decreasing after a point termed as pivot point. The value of burden at this pivot point was considered as optimal in this study. The best fit curve between EV and burden for three blasthole diameter and seven different width of vein were plotted. In all instances, the outputs of the model followed the second-degree polynomial equation. The study also suggests that the optimum burden reduces with the increase in the width of the vein. It has also been found that the optimum burden follows power trend with the increase in width of the ore body irrespective of blasthole diameter. Based on the optimum burden obtained from the output of simulation along with different blasthole diameter and width of the ore body, an empirical relationship has been established. The developed empirical relationship has a good agreement with the experimental trial data. Highlights: Numerical simulation technique has been used in this paper for the optimisation of burden while extraction of narrow vein stopes. The study suggest that the relation of volume of the excavated rock along the free face and burden is second-degree polynomial in nature. It has been found that the optimum burden for narrow vein is higher as compared to wider width ore body. Study also suggest that optimum burden follows power trend with the increase in width of ore body. The influence of width of the ore body in the selection of burden vanishes after certain width of ore body as per the observation of model output. [ABSTRACT FROM AUTHOR]

Burden is one of the most important parameter which plays an immense role in rock breakage using explosive energy. It is very difficult to select the optimum burden under different geotechnical and geomining condition. The selection becomes more critical when the excavation method is underground as very few researches or studies have been carried out in such cases. Therefore, in this paper, numerical simulation-based approach has been employed to estimate the optimum burden for ring blasting. The numerical models were created under different scenario including blasthole diameter and strength of the rock. The RHT concrete constitutive model has been used in this paper to study the damage contour under different circumstances. The model output has been used to calculate the volume of rock damage along the free face. This damage volume is further correlated with various parameters. This correlation shows that the damage volume along the free face initially rises with the increase in burden and then starts decreasing after a certain value. The burden value which recorded the maximum volume of rock excavated along the free face has been considered as the optimum burden in this paper. The trial blast has been also carried out at the experimental site for twenty-four rings. The optimum burden achieved from the experimental trial for 102 mm blasthole diameter and rock having uniaxial compressive strength as 92 MPa lies between 2.4 and 2.65 m. However, the optimum burden predicted through developed empirical equation from the numerical model is 2.6 m. The study shows that the simulation-based prediction exhibits a minor deviation within 15% with the experimental result. Hence, to assess the optimum burden under various geotechnical and geomining circumstances, numerical simulation-based approach may be carried out using the proposed methodology. [ABSTRACT FROM AUTHOR]

India is the leading producer of sheet mica and a major part of this is exported. Nellore mica belt is the largest mica-producing area covering part of Nellore district in Andhra Pradesh, India. As most of the mines are old and privately operated, they are developed and operated purely based on local experiences. In this article, we highlight the problems associated with the present mica-mining practices in the Nellore mica belt, and scientific approaches that have been adopted for fixing different parameters associated with mica extraction. Based on detailed field study, geo-mechanical data and tested rock properties, extensive numerical modelling is done to suggest the best possible method of mining for safe and sustainable mica extraction from the area. [ABSTRACT FROM AUTHOR]