Emerging explosives and initiation devices for increased safety, reliability and performance for excavation in weak rocks, mining and close to surface structures

摘要

Rock breaking, rock excavation, concrete breaking, foundation rock breaking, trenching, tunnel widening in sensitive environments such as close to high rise buildings, schools, hospitals, roads, electrical installations, existing and operative dam foundations, piers, pipeline laying below ground, indoors and secondary breaking of large rock boulders in quarries, are growing burning problem in most of the coal and other mines, big cities and metros. Uses of Drilling and Blasting with conventional explosives for rock breaking in such cases are either prohibitive because of the act, rules and regulations of the country's laws or not feasible due to local problems since even a controlled blasting technique causes vibrations, fly rock and noise beyond the permissible limits. In all such cases one of the big limitations is excavation output to meet the construction timetable. The rapidly growing civil excavation and infrastructure in India for sensitive rock breaking is estimated at about 5 million m~3 per annum. The NoneX rock breaking method, developed by NXCO Mining Technologies, has been extensively used in several applications in wide Varity of rock conditions. The NoneX technology allows a tailored rock breaking (TRB) approach whereby energy can be applied more efficiently to break and dislodge the rock in a controlled fashion, which can be optimally adapted to suit the rock breaking requirements of any particular situation in all types of rock conditions. NoneX cartridges with inbuilt detonators will not pose problems as the detonators contain explosives (similar to PETN powder) are also classified under Division 1.4S Chemicals by UN and classified as class-6/7 blasting caps explosive as per Indian explosive regulations, 1983/reaffirmed in 2005. The advantages of non-detonating Pyrotechnic system of rock breakage in open pit mining and civil construction sites greatly reduced the "danger Zone" to 30 m from 250 m with the conventional blasting because with this system the energy required to break a unit volume of rock mass was 1/10 of the energy required with the conventional blasting using high explosives. The lower use of energy resulted in significant reduction in fly rock, air blast and blast induced ground vibrations. In addition the over breaks were greatly reduced resulting in reduction of damage and supports to the rock mass. As a result of reduced evacuation distance of 20 to 30 m for personnel and equipment's the restrictions for continuous operation and excavation near the power lines, pipe lines and high rise buildings also significantly reduced thereby increasing the overall productivity. It is anticipated that the efficient use of non-explosive rock breaking techniques will make the concept of "Underground Space Technology" a more viable option in our cities where underground space will demand a premium in short term future. Underground space is an increasing popular option for car parks, and storage places in several highly urbanized areas and these non-explosive methods are one of the most applicable methods to use for excavation in most of the developing and developed countries where more and more stringent laws and regulations are being enforced with regards to disturbance.