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ROY, M. P.
- Yield Regulation in the Forests of West Bengal
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Indian Forester, Vol 87, No 12 (1961), Pagination: 751-757Abstract
The Forests of West Bengal have been divided into four geographical zones, viz., the Himalayan hills, the Duars, the Sunderbans and the Laterite zone. The floristics of each zone have been described. Shorea robusta is the only species which occurs gregariously in the Tista Valley, the Rangeet Valley, the Duars and the Laterite zone. Elsewhere the crop consists of an irregular mixture of a large number of species. Natural regeneration is inadequate except for some riverain species. The system of clear-felling followed by artificial regeneration with the help of taungya is applied in the Himalayan hills and the Duars to all such forests as are fit for conversion into a normal forest. Selection system is adopted for the riverain w forests and the Sunderbans. In the Laterite zone the long practised system of coppice with standards is followed. In the clear-felling system the yield is regulated by area alone. Only cultivable areas are taken into consideration during calculation. In the hills an allowance of 10% is made for retention of protection belts at necessary places. The age of the oldest plantation is tested with the conversion. Period to $atisfy the condition of exploitability of the oldest plantation at the end of conversion. In the riverain forests managed under the selection system, the yield of important species like khair, sissoo and semul is regulated by number of trees. Selection-felling of species in the riverain forests as well as the forests of the Sunderbans is regulated by area. In the coppice forests of the laterite zone, area forms the basis for yield regulation. Felling is so distributed over the felling series containing crops of various densities as to give roughly equal volume-yield each year.
- Damage to surface structures due to blasting – a new criteria
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Authors
M. P. ROY
1,
P. K. SINGH
1
Affiliations
1 CSIR–Central Institute of Mining and Fuel Research, Barwa Road, Dhanbad, India 826 015., IN
1 CSIR–Central Institute of Mining and Fuel Research, Barwa Road, Dhanbad, India 826 015., IN
Source
Journal of Mines, Metals and Fuels, Vol 64, No 9 (2016), Pagination: 9-19Abstract
This paper describes effect of blast produced ground vibration on damage potential to residential structures to determine safe levels of ground vibration for the residential structures and other buildings in mining areas. Impacts of 341 blasts detonated at two mines were monitored at the test structures and 1871 blast vibrations signatures were recorded on or near the test structures. Cosmetic cracks in a native brick-mud-cement house were detected at peak particle velocities (PPV) between 51.6 and 56.3 mm/s. The reinforced concrete and cement mortar (RCC) structure experienced cosmetic cracks at PPV's of 68.6 to 71.3 mm/s at the first floor, whereas at second floor it was detected at PPV levels of 71.2 to 72.2 mm/s. Minor damage in brickmud- cement house was recorded at PPV levels of 81.0 to 89.7 mm/s. The RCC structure at first and second floors experienced minor damage at PPV levels of 104 mm/s and 98.3-118 mm/s respectively. The brick-mud-cement house experienced major damage at PPV level of 99.6 to 113.0 mm/s, while major damage was recorded in RCC structure on first floor at PPV of 122 mm/s, the second floor at PPV levels of 128.9-161 mm/s. Recommended threshold limits of vibrations for the different type of structures is based on these measurements and observations.References
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