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Showing 3 results for Reliability

Masoud Zare Naghadehi, Seyed Davood Mohammadi, Mostafa Karimi,
Volume 12, Issue 2 (10-2018)
Abstract

Introduction
The selection of the best subsurface exploration methods corresponding to geotechnical, topographical and economic circumstances of the project is one of the most effective factors in the success of a tunneling project. On the other hand, the development of a decision model and consequently choosing the most suitable alternatives are complex tasks. Therefore, prioritizing and selecting the best subsurface exploration methods, as the main aim of this study, can reduce the economic and social costs associated with the execution of a tunneling project. For this purpose, ten experts from tunneling community have been asked to weigh the chosen criteria of the problem in this research. A methodology utilized in this study is the Analytical Hierarchy Process (AHP) which proved useful in engineering decision-making problems. The other method is TOPSIS, one that has continuously been used in decision making in the recent decades. These two techniques have been combined and utilized in this work to rank the aforementioned exploration methods.
 
 
Material and methods
The study area is located about 109 km far from Shahrekord city amid the Zagros mountains. The Sabzkooh tunnel development plan has been under evaluation in the time that this research was being done. The geology of the area majorly encompasses sedimentary rocks which have been outcropped as folds, faults, and fractured and altered zones. However, the variety of the lithological units in the tunnel route is high, and units of limestone and shales also exist over the path.
In the first step, geological and topographic maps were produced for the study area, and general information from the tunnel path was collected and examined. Suitable exploration methods were evaluated, and six main methods were chosen to be considered as the alternatives of the study including (a) discontinuities study, (b) Lugeon tests, (c) RQD, (d) Geo-electric, (e) Gravimetry, and (f) Seismic methods. Moreover, nine criteria ranging from “volume of the available information” and “environmental impact” to “cost” and “accuracy” of the employed methods were taken into account. A pairwise comparison matrix was then developed, and the experts were asked to fill it out. The importance of each criterion was then simply calculated through this matrix. Alternatives pairwise comparison matrices were also filled out and, in this manner, the alternatives could be ranked using the AHP technique. Next, the TOPSIS technique was employed for the same purpose using a rather different process.
Results and discussion
Both AHP and TOPSIS techniques show very close results for ranking of the alternatives in this study. They rank the three Seismic, Geo-electric and Discontinuities studies methods as the best ones for the considered tunneling project. The only difference between these two techniques is how they determine the worst method. The AHP ranks the Lugeon as the last rank among the six methods whereas the TOPSIS determines the RQD as the least reliable method of exploration for the Sabzkooh tunnel project.
 
 
Conclusion
The prioritization and the subsequent selection of the most reliable exploration methods for an underground excavation project is a crucial task amid technical decisions. In this research, two major multi-criteria decision-making methods including AHP and TOPSIS were considered and applied for the Sabzkooh tunnel in Iran. The results indicate a high agreement between the two methodologies even though these two approaches decide differently on the least reliable methods to be applied.
Mr. Mohammad Alizadeh Mansouri, Dr. Rouzbeh Dabiri,
Volume 16, Issue 1 (5-2022)
Abstract

In this study, it is attempted to analyze sensitivity and reliability in order to evaluate the liquefaction potential in soil layers in Tabriz. 62 boreholes that had possible conditions for liquefaction were selected. Seismic mapping was simulated using finite fault method and then the effect of soil layers on PGA was estimated. In continue, the liquefaction potential index was estimated and the zoning map of liquefaction risk was presented. In final, through sensitivity and reliability analysis of the Monte Carlo method, the rate of density function against safety factor of the soil layers versus to liquefaction was determined.
Dr Sayed Ali Asghari Pari,
Volume 18, Issue 1 (5-2024)
Abstract

Pile design is subject to a number of uncertainties that must be addressed to ensure the reliability and safety of the foundation. A common approach to reduce uncertainties in pile design is to calibrate the resistance factor in the Load and Resistance Factor Design (LRFD) method through reliability analysis. However, it is important to recognize that the LRFD method may not fully account for uncertainties associated with soil and pile resistances. The results of this study show that the separate consideration of base and wave resistance can lead to a more accurate and reliable design of piles. The proposed method can help engineers make more informed decisions and reduce uncertainties in pile design. In addition, the study highlights the importance of considering different factors such as the ratio of dead to live load and the ratio of base to shaft resistance when calculating the resistance factor.


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