An experimental study on rock damage and its influence in rock stress memory in a metamorphic rock
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ORIGINAL PAPER
An experimental study on rock damage and its influence in rock stress memory in a metamorphic rock Vinoth Srinivasan 1
&
Tushar Gupta 2 & T. A. Ansari 2 & T. N. Singh 2
Received: 2 May 2019 / Accepted: 24 April 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Rock stress memory, often referred as Kaiser effect, in rocks can be an effective tool to estimate the in situ stress conditions, if the uncertainties in rock damage and its behavior during loading conditions are properly understood. In view of this, the present study is an attempt to investigate the variations in rock stress memory, i.e., the Kaiser effect in a metamorphic rock under multi-stage uniaxial compression. The khondalite rock samples from Eastern Ghats Mobile Belt (EGMB) belonging to southeastern part of Indian subcontinent having complex geological history are examined. The effects of multi-stage compression on the damage evolution and subsequent variations in rock stress memory are investigated. The samples were categorized into different levels of rock stress memory, depending on the stress the rock was able to withhold after loading stages. The damage evolution in the tested rocks was predominantly controlled either by initial loading or failure stress. Higher damage imparted by initial loading and intense fracturing could be the possible reason for poor stress memory function in the investigated rock. Felicity ratio, an indicative of rock damage with stages of loading, supported the observation that rock damage was dominant during initial loading stage. Rock heterogeneity has played a dominant role in decay of Kaiser effect, with intense fracturing during subsequent loading stages in the investigated rocks. To summarize, Kaiser effect can be used to infer rock damage and stress conditions, provided the geological history of the region is also taken into consideration. With rocks from complex geological conditions, Kaiser effect or rock stress memory should be supported by other tools to infer in situ stress, but the method can be effectively used to understand the stress changes and damage mechanism of multiple loading. Keywords Khondalite . Acoustic emission . Kaiser effect . Rock damage . Felicity effect
Introduction
* Vinoth Srinivasan [email protected] Tushar Gupta [email protected] T. A. Ansari [email protected] T. N. Singh [email protected] 1
Department of Civil Engineering, National Institute of Technology Karnataka, Surathkal, Mangaluru 575025, India
2
Rock Science and Rock Engineering Lab, Department of Earth Sciences, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
Rocks in deep engineering structures are often exposed to cyclic and tiered mechanical loads due to many external factors such as blasting, locomotives, and induced fracturing. Such dynamic loading conditions often lead to complications in understanding the failure mechanism of rocks surrounding the engineering structures. Moreover, they could impose severe irreversible deformation well before
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