Abstract
Rockburst is a hazardous phenomenon in deep tunnels influenced by geological structural planes like faults, joints, and shear planes. Small-scale shear-plane-like structures have damaging impact on the boundaries of the tunnel, which act as barrier and accumulate high stresses. A shear plane combined with high stress conditions is very dangerous in deep excavations. Such a shear plane exposed in the side wall of the right headrace tunnel in the Neelum-Jehlum Hydropower Project. This project is constructed in the tectonically active Himalayas under high stress conditions. The influence of a shear zone on rockburst occurrence near the tunnel is studied. The FLAC3D explicit code simulated the shear zone in the right tunnel, revealing that the stresses are concentrated near the shear zone, while no such stress concentration is present in the left tunnel. The Rock mass got displaced near this shear zone. Modeling results confirm that the presence of shear zone in side wall of the right tunnel has a major influence on rockburst occurrence. A shear slip along this plane released huge amounts of accumulated energy, causing human fatalities and property damage. A comparison of numerical simulation with empirical rockburst criteria validates the actual conditions and help us to understand the phenomenon of stress concentration near the shear zone and its impact during deep tunneling.
Highlights
Rockburst is one of the most hazardous phenomena which intensify during construction of deeper excavations
This study focuses only the geological factor, which includes geological studies of the area and the influence of geological structures i.e., shear zone on the occurrence of rockburst
The shear zone was successfully simulated with this software to study danger of rockburst
Summary
Rockburst is one of the most hazardous phenomena which intensify during construction of deeper excavations. It can be caused by either brittle failure or slippage along structural planes in deep hard rock [1]. A lot of research work has been done to find the mechanism of rockburst in deep mining [3,4,5,6,7]. This phenomenon is not much studied in civil tunneling for hydropower and road projects. These include the Jinping hydropower tunnels in China, the Neelum-Jhelum Hydropower
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