Abstract
In the present work, dynamic stress-strain response of compact basalt is tested under high loading rates using 38 mm split Hopkinson pressure bar (SHPB) device. The physical and static mechanical properties of compact basalt, e.g., density, specific gravity, static compressive strength and elastic modulus values are also determined. Petrological studies of compact basalt are carried out through X-ray diffraction (XRD) test and scanning electron microscope (SEM) test. In the SHPB tests, it is observed from the stress-strain response that the dynamic peak stress increases with increasing strain rate however the elastic modulus is nearly constant with increase in strain rate. Dynamic force equilibrium at the incident and transmission bar ends of the rock samples is attained in all tests till the failure of the rock samples. Dynamic increase factor (DIF) for the rock is determined at a particular strain rate by comparing the dynamic to static peak compressive stress. Correlation equation for dynamic strength increase factor with respect to strain rate has been proposed herein.
Highlights
The Deccan trap region formed due to the lava flow in the Mesozoic era covers nearly 20% land area of India
The X-ray diffraction (XRD) graphs of compact basalt is compared with the available data from the literature and observed to be well in agreement [20]
The following conclusions are drawn from the high strain rate characterization of an igneous rocks e.g., compact basalt using uniaxial compressive split Hopkinson pressure bar (SHPB) device
Summary
The Deccan trap region formed due to the lava flow in the Mesozoic era covers nearly 20% land area of India. Many major underground tunneling projects are currently underway in this region for southern Indian railways where drilling and blasting activities take place on a regular basis. The region houses major hydropower projects and underground mining industries. Any natural or manmade hazard in this region may prove to be disastrous causing significant losses to Indian economy and mankind. The loads caused by hazardous events like earthquake and blast are highly transient in nature generating high strain rates in rock. The strain rate caused by blast may reach up to 104/s [1,2] which in turn affects both the stiffness and the strength properties of the rocks. For sustainable design of infrastructure in the Deccan trap region, it becomes necessary to characterize the rocks under static and dynamic loading conditions
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