Verma, H.K. and Samadhiya, N.K. and Singh, M. and Goel, R.K.
(2015)
Extent of Rock mass Damage Induced by Blasting in Tunneling.
Jour of Engineering Geology, 66 (7).
pp. 946-958.
Abstract
Drilling and blasting is preferred method of rock excavation world-wide due to low initial investment cheap explosive energy, easy acceptability amongst the blasting engineers, possibility to deal with different shapes and sizes of openinings. Although drill andblast method has witnessed significant technological advancements, it has inherent disadvantage of deteriorating surrounding rock mass due to developemt of network of fine caracks in it leading to safety and stability problem. The damage in the peripheral rock mass culminates in the form of overbrak and damanged zone. Overbreak increases project cost by more than 15%. The damaged zone extends beyond overbreak. Although significant efforts have been made to assess damage to the surrounding rock mass using different methods, easier solution based on easily available site parameters is still lacking. Authors have carried out field investigations at five different tunnel construction project sites located in Himalaya, India to formulate an empirical correlation for prediction of blast induced damamge for wide range of Q values (0.04 – 17.8). The proposed correlation is based on specific charge, perimeter charge factor, maximum charge per delay, advancement and confinement factor and rock mass quality rating Q. All the parameters used in empirical correlations are readily available to the site engineers and does not require laboratory testing. Data sets of 113 experimental blasts are collected from te five tunnel sites. The proposed empirical correlation has been validated using ultrasonic tests on rock core samples obtained from one of the experimental location.
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