In the present work, dynamic stress-strain response of Himalayan quartzite is tested under high loading rates using split Hopkinson pressure bar (SHPB) device for the first time in the literature. The physical and static mechanical properties of quartzite e.g. dry and saturated density, specific gravity, static compressive strength and elastic modulus values are also determined. Petrological studies of quartzite 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 whereas the elastic modulus does not show any clear trend 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.

1. Introduction

Design, development and building of civil infrastructure in the mountainous regions involve many complexities in terms of diverse geological and geomorphological features of the region - the Chenab river bridge in the Himalayas, the Gotthard Base tunnel in the Alps are to name a few. The young mountain ranges of the Himalayas and the Alps contain joint planes, shear seams, active fold, and fault zones. Moreover high in-situ stresses and high level of seismicity in these regions pose severe challenges to the construction of infrastructure. In addition to this, unanticipated loads caused by natural hazards, e.g. landslide, earthquake and manmade hazards, e.g. blast and projectile penetration add to the difficulties already existing therein. It may be noted that the loads caused by hazardous events like earthquake and blast are highly transient in nature generating high strain rates in rock and strain rate caused by blast may reach up to 104?s−1 [1, 2] which in turn affects both the stiffness and the strength properties of the rocks. Thus, in order to ensure sustainable design of civil infrastructure in the mountains, it becomes necessary to characterize the rocks under static and dynamic loading conditions.

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