| Abstrakt: |
The Mithi River is confluence of the tail water discharges of Powai and Virar Lakes, and flows through Sakinaka, Santacruz, Kalina, Vakola, BKC, Dharavai before meeting the Arabian sea at Mahim Creek, stretching over17.84 KM. As Mithi river was considered one of the reason for Mumbai flooding in year 2005 that paralysed the city. The Mumbai Metropolitan Regional Development Authority(MMRDA) has undertaken deepening the river bed, to increase discharge capacity as hard rock is encountered for stretch of 2 KM, where it meets Sea. This lead to bed rock blasting by specialized underwater blasting techniques near sensitive structures like flyover, Mahim Causeway, Dharavi Bridge, Railway Track and old Pipeline of water supply. Control of vibrations and fly rock were important objectives of the project along with desired fragmentation. Also, stop special attention has to be given on protecting Marine life. As we were approaching away from sea, tide head was not sufficient to conduct blasting under sufficient water head as chances of fly rock were to greater extent. Special Odex System of drilling was carried out in Overburden filling. Couplable Plastic Tube (CPT) Seismic Explosive used with Specific Charge ranging from 0.49 Kg/M³ to 0.59 kg/ M³ and specific drilling was0.88 to 1 M/M³ to restrict better fragmentation. The ground vibration limit was restricted below 10 MM/S, which was threshold limit given by CIMFR, considering nearby sensitive structures. The desired fragment size below 0.7 M? was achieved without compromising safety standards. OB Filling and blasted rock can be easily removed throughout high tide by deploying 1 M? bucket capacity excavator. [ABSTRACT FROM AUTHOR] |
