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Ojha B.K.,Energy Infratech Pvt. Ltd
Water and Energy International | Year: 2015

The backfill concrete behind steel liner in 650 m deep pressure shaft at Teesta-III was quite challenging as provision of stiffeners hardly left a gap of 300 mm from the excavated rock surface. In view of time constraint the concreting activity was planned by pumping concrete from bottom so as to continue steel liner erection independently. The ease of placement and better flow ability/ filling ability of self-compacting concrete (SCC) without vibration prompted the decision of using SCC as backfill concrete though it is little costlier than conventional concrete. The fly ash was used in concrete mix to have better durability and shrinkage characteristics and to avoid thermal problems. Extensive laboratory trials were done to optimize the cement and fly ash content for the SCC mix and achieve the required properties for the hardened concrete and cost competitive at the same time. The SCC was done successfully and its placement and performance was monitored through testing of flow ability characteristics and testing of cubes. This paper summarizes the various mix design and itsfield performanceat pressure shaft of Teesta-III project.This study could provide better understanding and utilization of SCC in upcoming projects in a more economical way. © 2015, Central Board of Irrigation and Power. All rights reserved. Source


Ojha B.K.,Energy Infratech Pvt. Ltd
Water and Energy International | Year: 2015

Concrete is among the principal dam construction material and with changing times there has been huge demands for the enhanced properties of concrete especially in high strength and high performance, low heat of hydration, cracking resistance, and abrasion and cavitation resistance etc. The hydraulic structures like spillway, stilling basin, tunnels etc are subjected to high velocities leading to heavy abrasion and cavitation erosion due to silt laden water. Damages have been found to occur in spill ways, invert of diversion tunnel, flushing tunnel and outlet structures etc. ranging from few centimeters to meters. Such damage has been observed in most of the dams in India and even in advanced countries and has been an area of concern for engineering fraternity. In order to improve the performance of concrete to resist abrasion and erosion, a high strength and high abrasion and erosion resistant concrete containing super plasticizer and silica fume are developed and are in use in most of Dam projects. Teesta III hydroelectric project (6×200 MW) is a run of the river scheme and is located on Teesta River just 400 m downstream of confluence of Lachen chu and Lachung chu, the two limbs of Teesta. The chute spillway glacis, diversion tunnel and flushing tunnel shall be negotiating very high velocity and therefore high performance concrete (HPC) has been used in these works. The high performance concrete was designed at the project and the laboratory program was undertaken for mix design trials and evaluation of the abrasion resistance of concrete mixes. Since the aggregates were potentially alkali reactive, PPC cement (fly ash based) was used for the job. This paper summarizes the details of trial concrete mixes and evaluation of their erosion resistant characteristics. © 2015, Central Board of Irrigation and Power. All rights reserved. Source


Aggarwal S.K.,Teesta Urja Ltd | Ojha B.K.,Energy Infratech Pvt. Ltd
Water and Energy International | Year: 2014

The Teesta Concrete Face Rockfill dam is under construction in the State of Sikkim. The project construction started in 2008 and is presently in advanced stage of completion (likely completion March 2015) in spite of stoppage of work for about 18 months due to earthquake and cloud burst in the project area and the other contract issues with the owners and contractors. The 60 m depth of the overburden in the riverbed with boulders present ruled out excavation upto fresh rock and hence CFRD with upstream plastic concrete cut-off wall (60 m Deep) was adopted. This paper focuses on design and construction characteristics of CFRD in such respect as general layout, cross section design, facing design, design of joints and water stops, foundation treatment etc. The purpose of this paper is to highlight the constructional advantage compared to other types of dam especially in respect of easy availability of embankment materials as well as shorter construction period independent of seasonal change. Also the possible division of foundation treatment and embankment work, high resistance against earthquake and stability against water leakage is the additional advantage. Largely the design and construction of this CFRD has been based on principles and experiences as applied internationally and gained from the Dhauliganga CFRD of NHPC with regard to zoning, fill materials, foundation excavation, grouting plinth and face slab etc. The constructional features of CFRD have been enumerated in the paper for future reference as well. © 2015, Central Board of Irrigation and Power. All rights reserved. Source


Lodhi M.S.,Gb Pant Institute Of Himalayan Environment And Development | Agrawal D.K.,Energy Infratech Pvt. Ltd
Journal of Mountain Science | Year: 2012

The precision modeling of dam break floods can lead to formulation of proper emergency action plan to minimize flood impacts within the economic lifetime of the assets. Application of GIS techniques in integration with hydrological modeling for mapping of the flood inundated areas can play a momentous role in further minimizing the risk and likely damages. In the present study, dam break analysis using DAMBRK model was performed under various likely scenarios. Probable Maximum Flood (PMF) calculated for a return period of 1000 years using deterministic approach was adopted for dam break analysis of the proposed dam under various combinations of breach dimensions. The available downstream river cross-sections data sets were used as input in the model to generate the downstream flood profile. Dam break flow depths generated by the DAMBRK model under various combinations of structural failure are subsequently plotted on Digital Elevation Model (DEM) of the downstream of dam site to map the likely affected area. The simulation results reveals that in one particular case the flood without dam may be more intense if a rainfall of significant intensity takes place. © 2012 Science Press, Institute of Mountain Hazards and Environment, CAS and Springer-Verlag Berlin Heidelberg. Source


Chandra U.,Uttarakhand Technical University | Bhardwaj C.K.,Uttarakhand Technical University | Bhardwaj C.K.,Dehradun Institute of Technology | Kumar P.,Uttarakhand Technical University | And 3 more authors.
Indian Journal of Environmental Protection | Year: 2013

Water is used by industry in many ways for cleaning, heating and cooling and generating steam, as a solvent and for transporting dissolved substances and as a constituent part of the industrial product itself. Withdrawal of water for industry is usually much greater than the amount actually consumed. Following major growth between 1960 and the 1980s, water withdrawal for industry worldwide has more or less stabilised; falling in Europe and rising steadily, but not as rapidly as previously, in Asia. In areas where surface water resources are scarce groundwater is used to meet industrial demand. While it is often difficult to obtain specific data concerning groundwater withdrawal for industry, it clearly remains a fraction of that used for agriculture. Increasingly, industrial wastewater management must be coordinated with and integrated into, overall water management of the region. While almost all liquid fresh water of the planet occurs underground, its long term suitability as a source of water is threatened by point source of pollution from industrial and by aquifer depletion due to groundwater withdrawals in excess of groundwater recharge. Hence, industrial wastewater can be an important water resources but its use must be carefully planned and regulated to prevent adverse health effects and undue contamination of ground water. Because of local ground water can be used for purposes with higher social or economic returns or saved for the future. © 2013 - Kalpana Corporation. Source

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