Contribution of AHP method in prioritizing risk factors regarding tunnel project phases

المجلة: Periodicals of Engineering and Natural Sciences

سنة النشر: 2020

تاريخ النشر: 2020-12-15

Tunnel projects are consistently regarded to be mostly a complex and risky engineering projects, owing to the features of the projects, since they increasingly achieve high risk and complexity during the execution of the project. this led to the fact that the necessity of risk management understanding and implementing is a crucial quest with the intention to obtain tunnel project objectives considering (time, cost, quality & safety) to avoid time and cost overruns and any other obstacles. it was observed the most affecting objective was Safety (47.3%) by AHP method in which it is actually reasonable as such project of tunnel need a great concern regarding that matter for many reasons for instance the closed construction area, ventilation considerations, blasting, and so on. the second major objective is quality (31.1%) in which as experts always say it has to be maintained as a high quality as possible.

Extent of Risk Management Implementation in Some of Rock Laboratory Tests for Tunnel Projects by Means of AHP Method

المجلة: Periodicals of Engineering and Natural Sciences

سنة النشر: 2020

تاريخ النشر: 2020-10-15

In any project, especially infrastructure ones such as tunnels, tests play a major role in predicting and showing the properties of the ground built on. For such construction through a rock mountain terrain, it is quite not easy to predict the engineering property of such materials. Since working with rock is a quite challenge because of the nature of rock materials, it needs a lot of care and persuasion when dealing with such. For such rock materials, it needs both of field and laboratory tests to ensure the process of obtaining the final engineering property of the materials. This paper concentrate on some of the laboratory tests required for tunnel project held in rock profile sites. Emphasizing on safety, accuracy that enquired during such tests and try to run those under risk management process by means of AHP to get the responded weights for those factors such as test procedure with average of weight (49.43%) indicates the caution to be taken during test beside major parameters such as sample size and mass in accurate manner to avoid risk in test and results obtained.

Investigating The Status of Risk Management System in Tunnel Construction Projects

المجلة: Journal of Global Scientific Research

سنة النشر: 2020

تاريخ النشر: 2020-10-04

Tunnel projects considered as one of the complex and dangerous infrastructure projects due to the attribute of such projects as it progressively achieves highly risk and uncertainties during project implementation. Such kind of projects is highly expected that a real and dependable system of risk management to be implemented throughout the project phases to ensure the completion in a best way possible. Unfortunately, in reality, it is away far from expectation for the projects of tunnel implemented here in Iraq because no reasonable system of risk implemented just only a construction management system that depends only on the experience of the project staff and some expert senior engineers with no availability of a dependent system of risk control and management. The paper will provide investigation regarding reality of risk system in tunnel projects with the aid of questionnaires and provide such fact that there is a low limited knowledge of risk management concept. Using principle of like hood and impact concepts risk matrix conducted. Forty-four risk factors presented through the study and prioritize depending on their risk degree, accordingly top ten risk factors presented. Throughout the results by means of data collected during the survey, it was clear that the results were heading to such a fact that risk management is not implemented; and applied in such projects. Results regarding risk management concepts were in range (66.67 up to 100%) were with negative answers. this led to the fact that the need for risk management understanding and implementing is a crucial quest with the intention to obtain tunnel project objectives considering (time, cost, quality & safety) to avoid time and cost overruns and any other obstacles.

Degradation Mechanisms and Residual Mechanical Properties of Reinforcing Steel Bars Exposed to Natural and Artificial Corrosion – Review & Analysis

المجلة: Polytechnic Journal

سنة النشر: 2023

تاريخ النشر: 2023-02-12

Reinforcement corrosion is the most problematic phenomenon and one of the main sources for the degradation of structures and infrastructures all across the world, that leads to their premature deterioration before design life has been attained. Therefore, the structural effects of rebar corrosion are crucial in determining the structural performance and residual strength of impaired structures. In the present work, the corrosion initiation mechanisms, corrosion products, corrosion types, corrosion consequences on structural performance and detrimental factors related to corrosion were presented in brief. Moreover, the propagation period and the main consequences on mechanical properties of steel and concrete are analyzed. Analyses of the available statisticaldata collected from literature were performed for 443 specimens. The findings are further interpreted from structural point of view, and deterioration equations for the mechanical properties of the corroded reinforcements are developed. The relations are well analyzed, leading to the definition of decay equation for yielding and ultimate stresses, and ultimate strain. It was found that the mass loss of 1% due to the rebar corrosion can cause the strength loss of 1.34%, 1.30%, and 3.54% respectively for yield strength, ultimate strength, and elongation. The suggested formulas can be applied in analytical and numerical structural applications.