scholarly journals Effectiveness of Post-injection Grouting in Controlling Leakage: A Case Study

2012 ◽  
Vol 8 ◽  
pp. 14-18
Author(s):  
Krishna Kanta Panthi

In many occasions severe water leakage problems are faced in shotcrete lined or unlined water tunnels that not only reduce stability of the rock mass but also result in loss of valuable water in conveying tunnel systems. Such leakage causes safety risks and increases the potential for huge economic loss to the hydropower projects. On the other hand, use of full concrete lining as final support increases the construction cost and time considerably. The best way to reduce leakage control and construction costs and time is the use of pre-injection grouting in the headrace tunnels. This paper discusses the role that post-injection grouting has played for controlling leakage through shotcrete lined/unlined low pressure headrace tunnel of the 60 MW Khimti I Hydropower Project in Nepal. DOI: http://dx.doi.org/10.3126/hn.v8i0.4903Hydro Nepal: Journal of Water, Energy and Environment Issue No. 8, 2011 JanuaryPage: 14-18Uploaded date: 16 June, 2011

2013 ◽  
Vol 12 ◽  
pp. 39-44 ◽  
Author(s):  
Kaspar Vereide ◽  
Leif Lia ◽  
Laras Ødegård

Investments in hydropower pumped storage projects (PSP) are subjected to a high degree of uncertainty. In addition to normal uncertainties in hydropower schemes, the profit of a pumped storage scheme is dependent on the margin between power prices for buying and selling, which is difficult to predict without a power purchase agreement (PPA). A PSP without a PPA and without known construction costs requires quantification of the uncertainties in order to make qualified decisions before investing in such projects. This article demonstrates the advantages of using Monte Carlo (MC) simulations as a tool in the economic analysis of PSPs. The method has been tested on a case study, namely the Tamakoshi-3 Hydropower Project (HPP) in Nepal. The MC method is used to calculate the probability distribution of the net present value of installing reversible units in the Tamakoshi-3 HPP. The calculations show that PSPs may be profitable in Nepal, given a beneficial development of the power market. The MC method is considered to be a useful tool for economic analysis of PSPs. In this case study of installing reversible units in the Tamakoshi-3 HPP, there are many uncertainties, which the MC simulation method is able to quantify. Hydro Nepal; Journal of Water, Energy and Environment Vol. 12, 2013, January Page: 39-44DOI: http://dx.doi.org/10.3126/hn.v12i0.9031 Uploaded Date : 10/29/2013


2019 ◽  
Vol 11 (8) ◽  
pp. 2195 ◽  
Author(s):  
Chen-Yi Sun ◽  
Yin-Guang Chen ◽  
Rong-Jing Wang ◽  
Shih-Chi Lo ◽  
Jyh-Tyng Yau ◽  
...  

The green building certification system of Taiwan, EEWH (Ecology, Energy Saving, Waste Reduction and Health), has been in operation for more than 20 years (since 1999). In order to understand the relationship between green building certification and the construction costs of residential buildings, this study obtained 37 green building-certified residential cases and 36 general residential cases available from public information and conducted a comparative analysis. The results of this study showed that the average construction cost of a green building certification residential building was only 1.58% higher than a general residential building, indicating that green building certification does not require a large increase in costs. However, for residential buildings, achieving a high-grade (gold-grade or diamond-grade) green building certification means an increase of 6.7% to 9.3% in construction costs. This shows that the pursuit of higher levels of green building certification does require higher construction costs. In addition, the results of this study can not only provide important references for the government in making green building policies, but also offer a practical strategy for developers for decision-making.


Buildings ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 170 ◽  
Author(s):  
Theodora Mavridou ◽  
Lambros Doulos

Used properly, daylight can provide visual comfort, reduce energy consumption and improve health and safety at work. This paper investigates the influence that different roof types, (i.e., sawtooth roof, skylight and monitor), have on daylight levels, along with the construction cost in an industrial environment in Athens, Greece. Construction costs and daylight adequacy/uniformity are antagonistic phenomena, since as the distance between the roof openings increases, the construction cost is minimised, while the daylight levels and the uniformity are reduced. Therefore, an optimisation method is proposed in order to find the optimum distance between the roof openings. The selected building is a representative unit of Greek industrial facilities, while the optimisation method is based upon a multiparametric approach. This consists of three (3) different roof opening arrangement types with different geometric characteristics. The daylight metrics used are the Daylight Area, the Daylight Factor, the Mean Daylight Autonomy, the Uniform Daylight Index and the Annual Sunlight Exposure. Overall, sawtooth roofs represent the best choice for daylight provision in industrial buildings at the examined geographic location. Using the aforementioned optimisation method, the optimum solution of distances between the roof openings ranges from 10 m to 13 m.


Author(s):  
Mostafa Namian ◽  
Mohammad Khalid ◽  
George Wang ◽  
Yelda Turkan

Unmanned aerial vehicles (UAVs) have gained their prevalent recognition in construction because of their exceptional advantages. Despite the increasing use of UAVs in the industry and their remarkable benefits, there are serious potential safety risks associated that have been overlooked. Construction is one of the most hazardous industries in the United States. In addition to the ordinary hazards normally present in dynamic construction workplaces, UAVs can expose workers to a wider range of never-before-seen safety risks that must be recognized and controlled. The industry is not equipped with safety measures to prevent potential accidents, because of scarce research on drone-associated hazards and risks. The aim of this research was to (1) identify the UAV-associated hazards in construction that may expose personnel and property to potential harms, and (2) study the relative impact of each hazard and the associated safety risks. In Phase I, the researchers conducted an extensive literature review and consulted with a construction UAV expert. In Phase II, the researchers obtained data from 54 construction experts validating and evaluating the identified hazards and risks. The results revealed that adopting UAVs can expose construction projects to a variety of hazards that the industry is not familiar with. “Collision with properties,”“collision with humans,” and “distraction” were identified as the top three safety risks. Moreover, the study introduces effective strategies, such as having qualified crew members, proper drone model selection, and drone maintenance, to mitigate the safety risks. Finally, a post-hoc case study was investigated and presented in this article.


2021 ◽  
Author(s):  
Matthew Kelsey ◽  
Magnus Raaholt ◽  
Olav Einervoll ◽  
Rustem Nafikov ◽  
Stian Amble

Abstract Multilateral technology has for nearly three decades extended the production life of fields in the North Sea by delivering a higher recovery factor supported by the cumulative production of the multiple laterals. Additionally, operators continue to look at methods to reduce the environmental impact of drilling and intervention. Taking advantage of the latest multilateral technology can turn otherwise unviable reservoirs into economically sound targets by achieving a longer field life while minimizing construction costs, risk, and environmental impact. This paper will focus on mature fields in the region that have used multilateral applications for wells that were reaching the end of their life and have been extended to further economic production. This paper discusses challenges faced to provide a multilateral solution for drilling new lateral legs in existing wells where there is a lack of available slots to drill new wells. Additionally, discussion will cover completion designs that tie new laterals into existing production casing. The case study will include discussion of workover operations, isolation methods, and lateral creation systems. The paper focuses on the challenges, solutions, and successful case study of a retrofit multilateral well constructed in the North Sea which extended production life in a mature field by using innovative multilateral re-entry methods. The paper also provides insight as to methodology for continually improving reliability of multilateral installations to maximize efficiencies.


2012 ◽  
Vol 2 (2) ◽  
pp. 27-35
Author(s):  
Hong Xiao ◽  
David Proverbs

Construction cost is a major concern to both clients and contractors. Based on a hypotheticalconstruction project (a six-storey concrete framed office building), cost and otherrelated information was collected through a survey of contractors in Japan, the UK and theUS. Using multiple regression analysis it was found that lower overheads, less prefabricatedcomponents, and fewer design variations could reduce construction cost. Overheadslargely represent indirect costs to contractors and if reduced can lead to increased profitlevels and improved competitiveness. The use of prefabricated components may be problematicwhere there are delays in production, insufficient coordination between design andconstruction, and congested transportation on site. Design variations during constructionbring about uncertainties and are disruptive to the construction process. These factorshave paramount impact on construction cost and demand close attention and consideration.Contractors are advised to reduce the costs of their overheads and utilise prefabricationappropriately, while clients and designers should minimise the number of designvariations during construction if better cost performance is desired.


2010 ◽  
Vol 163-167 ◽  
pp. 2709-2714
Author(s):  
Feng Guo ◽  
Wei Ya Xu ◽  
Fei Xu

Evaluation of slope stability in the hydropower project construction is extremely important. This Cloud Model will be introduced to the matter-element extension, the extension assessment is proposed based on the sutra field division of the slope stability assessment model. This method combines the Cloud Model theory and the advantages of the extension assessment .On the one hand, the division of the sutra field by means of Cloud Model can overcome the "hard" division of the evils. On the other hand,with different values of Cloud Drops as a sutra field, the statistical results of Cloud Drops can be used as last stable assessment results. Project case study shows that compared with the conventional method, results of the method of extension are more accurate, which fully accorded with the actual state, proving optimized based on Cloud Model extension assessment of slope stability feasible and effective.


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