This paper presents static and dynamic experimental characterization of quartzite rock subjected to static unconfined compressive strength test and dynamic split Hopkinson pressure bar (SHPB) tests. The dynamic compression tests on rock samples are performed at strain rates from 10−1/sec to 103/sec. It is observed from the results that the rocks exhibit significant strain rate sensitive behavior and the peak stress increases with increasing strain rate. In the present work, the force equilibrium at the incident and transmission bar ends of the rock samples have been studied and reported. Dynamic increase factor (DIF), i.e. the ratio of the dynamic to static peak stress has been calculated at different strain rates. Based on the calculated DIF values, an empirical correlation equation has been proposed for the DIF of the rock with the strain rate induced.
Hydropower projects in the mountains are the backbone for electricity generation and irrigation project which plays a crucial role in the socio economic development of a nation. Natural hazards like near fault earthquake, tectonic activities or manmade hazards like bomb blast, projectile attack, may cause significant damage to the hydroelectric structures and the underlain rock mass thus leading to enormous loss for the nation. Hence, the rock mass supporting the structures should be characterized so that it can resist any unanticipated load in addition to the usual structural load and load from the surrounding rock mass. The unanticipated loads often lead to high rate of loading in the surrounding rock with a strain rate in the range of 102/sec~104/sec (Ngo et al. 2007, Dusenberry 2010). Both the strength and the stiffness of rocks are affected when subjected to such high rate of loading. Hence, it is necessary to characterize the response of rocks at such high strain rate for adequate design of the infrastructure through experimental and numerical investigations.
