Papers by Vinoth Srinivasan
Bulletin of Engineering Geology and the Environment, 2020
Rock stress memory, often referred as Kaiser effect, in rocks can be an effective tool to estimat... more Rock stress memory, often referred as Kaiser effect, in rocks can be an effective tool to estimate the in situ stress conditions, ifthe uncertainties in rock damage and its behavior during loading conditions are properly understood. In view ofthis, 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 ofrock damage with stages ofloading, supported the observation that rock damagewas dominant during initial loading stage. Rock heterogeneity has played a dominant role in decay ofKaiser 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 ofthe 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.
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Engineering Geology, 2022
Thermal damage is one of the fundamental mechanisms affecting the stability of rocks encountered ... more Thermal damage is one of the fundamental mechanisms affecting the stability of rocks encountered in many deep geo-engineering ventures such as nuclear waste isolation, geothermal extraction etc. In the present study, the findings on influence of heating and subsequent cooling conditions on the fracturing and mechanical behaviour of an Indian granite are discussed. The granite samples from Jalore region of India were heated from room temperature to 600 ◦C followed by slow cooling and water quenching treatments. It was observed that rapid cooling through quenching had a greater impact on strength, elastic properties than slow cooling rate. Moreover, a drastic shift in terms of fracturing thresholds was witnessed, as a function of both temperature and sudden thermal shock experienced by rock at higher cooling rate. The simultaneous AE monitoring results suggested an early crack damage at higher thermal regimes. With help of microscopic observations, it was observed that inter- granular crack boundaries widened with increasing thermal damage experienced by minerals under both cooling conditions. However, the fracturing process was intense under rapid cooling treatment due to the invasion of water due to quenching which accelerated severe intra-crack growths, especially at higher thermal stress because of the rapid cooling rate than the slow cooling. The increased intensity of thermal cracks with temperatures and with variation in cooling rate was inferred as the primary reason for decay of rock characteristics. This was very well supplemented by decay in strength properties and changes in fracturing attributes of the tested granite as inferred from acoustic monitoring.
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Rock Mechanics and Rock Engineering, 2020
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The application of microseismic monitoring in opencast coal mines provides an ideal method for th... more The application of microseismic monitoring in opencast coal mines provides an ideal method for the analysis of slope status. Since slope angles are critical to the economics of open pit mining, microseismic monitoring of fracturing within a slope can add significant knowledge to assess the status of slopes in terms of stability. An advanced high dynamic range microseismic instrumentation with latest computer methods/analysis will help to investigate strata behavior in real time. In the present study, an array of high frequency 15 Hz triaxial geophones were installed in boreholes in Opencast Coal Mine in highwall as well as dumps for monitoring the slope movements. The microseismic energy generated due to rock movements is continuously recorded by these geophones. The recorded events are stored in seismic recorder. The stored data will be transferred into a data acquisition and processing system via wireless repeater station. The data recorded are later processed for their origin of ...
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Groundwater regions in coastal aquifers are highly vulnerable with increase in urbanization, indu... more Groundwater regions in coastal aquifers are highly vulnerable with increase in urbanization, industrialization and sea water intrusion. The present study attempts to evaluate the vulnerability of groundwater in a coastal watershed of shrimp farming areas. The study area is categorized in the GIS-based AHP environment into three ranges (high, medium, and low vulnerability) using various groundwater parameters such as electrical conductivity (EC), total dissolved solids (TDS), sodium percentage (Na%), total hardness (TH), revelle coefficient , sodium adsorption ratio (SAR), permeability index (PI), and residual sodium carbonate (RSC) and their recommended limits. GIS-based AHP weighted index overlay analysis technique has been proven to be a powerful tool to evaluate the distribution of groundwater vulnerability in the study area. The high vulnerable areas were noted in downstream with a strong contamination of the seawater intrusion along the coastal zone and in proximity of the river. Multivariate statistical techniques are also applied to identify and assess the groundwater vulnerability of the study area. The factor analysis revealed that groundwater quality is strongly affected by rock–water interaction, saline water intrusion, and anthropo-genic activities. The spatial distribution map of factor-scores showed the gradual variation in groundwater geochemistry from the western part (upstream) to the eastern part (downstream) of the river. The results from the present study revealed that shrimp farming areas have very least or no impact on the groundwater of the region.
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The application of a routine high resolution microseismic monitoring system installed in an openc... more The application of a routine high resolution microseismic monitoring system installed in an opencast coal mine for monitoring highwall slope failures is discussed. A PC based microseismic network consisting of geophones, data loggers, GPS synchronization and Ethernet antennas for wireless communication is employed to study the impact of induced seismicity on the slope failures in real time. The study aimed to understand the rock mass response to mining induced seismicity from the behavior of seismic events within rock mass. The level of induced seismicity due to underground excavation is determined from the seismic source parameters such as locations, magnitude, and seismic energy. The status of the slope is assessed by the quantification of the microseismic events. The understanding of spatial and temporal distribution of the seismic events within the mining district correlated well with the existing geological structures and the excavation sequence. The application of microseismic system in the opencast mine has not only yielded confident results, but also marked as an effective tool for continuous monitoring of seismicity on the deep opencast slopes for mitigating the seismic risks and hazard management.
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Conference Presentations by Vinoth Srinivasan
INDOROCK2016
The excavation of rock mass alters the stress condition within the slope thereby making it suscep... more The excavation of rock mass alters the stress condition within the slope thereby making it susceptible to deform over a period of time. This may eventually lead to the failure of slope due to movements along the weak planes. Several monitoring techniques such as visual inspection, laser scanner, Lidar scanning, total stations, global positioning systems (GPS) to the state of art radar scanning and microseismic monitoring are currently being practiced in mine environments for predicting slope failure and deformation rate. The paper will present need of routine slope monitoring system, their classification and the status of various available slope monitoring technologies. The paper suggests that a regular long term slope monitoring technique based on ground realities is necessary in planning large and deep opencast mines for ensuring high safety and increased productivity
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articles by Vinoth Srinivasan
A thorough knowledge on pore size distribution (PSD) is one of the fundamental requirements for c... more A thorough knowledge on pore size distribution (PSD) is one of the fundamental requirements for characterization of shale gas reservoirs and for accurate estimation of their gas storage potential. However, being an important future source of energy need in India, the pore size distribution of Indian shale gas systems is not scientifically well understood. In the present study, the nanoscale pore size distributions of prospective Indian shale basins, viz., Cambay, Cauvery, Krishna-Godavari (K-G), and Damodar valley (DV), were investigated using mercury injection porosimetry (MIP) and low-pressure gas adsorption (LP-N2 and LP-CO2) techniques. The study focused on identifying the priority basins for shale gas production which can be substituted for sequestration of CO2 based on their PSDs. The samples exhibited higher thermal maturity with increasing organic content. The chemical composition of the shale samples was inferred from XRD data, which depicted higher clay content. The prominent clay minerals identified muscovite, illite, and kaolinite, which are generally flaky in nature. These minerals contributed significantly to the pore size complexity of the studied shale samples. The experimental result suggested that the samples exhibited diversified pore size characteristics. The shales are chiefly bimodal, consisting of mesopores (2-50 nm) and micropores (<2 nm). The micropores were efficiently accessed using CO2, while N2 was effective on characterizing the mesopore region. MIP analysis was used to infer the pore throat area. The average pore diameter of samples ranged from 3.38 nm in Damodar valley to 3.94 nm in thr K-G basin, while Cauvery and Cambay basin samples possessed 3.88 and 3.86 nm, respectively. Both N2 and CO2 adsorption (type II and type I, respectively) suggested the presence of micropore infilling in all of the basin samples. However, Cauvery basin samples were inferred with higher mesopore content as compared to other basins and possessed higher quartz percentage, making it more appropriate for hydraulic fracturing. The Cauvery basin showed enrichment of larger pore sizes. The results signified that the Damodar valley shales have a higher affinity toward CO2 adsorption. This suggested that the basin could be a better host for future carbon storage, compared to other basin pore structures.
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Papers by Vinoth Srinivasan
Conference Presentations by Vinoth Srinivasan
articles by Vinoth Srinivasan