vikor

The project management involves time management, cost, quality and risk of the project. Each project has time constraints, cost and quality. Since each of these constraints have a potential for risk, therefore, project risk management is essential. Increasing the cost and expanding the scale of projects on the one hand and increasing the uncertainty and risk of projects on the other hand has made risk management and assessment important. The purpose of risk management and assessment is to identify and evaluate accidental events that can have a positive or negative impact on project goals. In this study, a hybrid model for managing and evaluating the risks associated with tunneling operations using Multiple-criteria decision making methods is presented. After identifying the risks and performing the Delphi process, Risk Breakdown Structure (RBS) was used to categorize the risks , Analytical Hierarchy process (AHP) has been used for risk weighting, and VIKOR multiple-criteria decision making has been used to determine the risk ratings. The results showed that among the risks, the risk of manpower, Economic risk and management Risk were classified as critical risks.

Grouting operations as one of the main methods of ground improvement play a key role in tunneling quality. Grouting reduces the amount of surface subsidence, maximum loads on the support systems and on tunnel convergence by improving strength parameters of ground. On the other hand, grouting operation causes an increase in time and cost, and also reduces the continuity of tunneling operations. According to positive and negative effects of grouting operations in tunneling projects, selecting the optimum grouting radius is very important. Vertical displacement of the crown and the roof of the tunnel, the horizontal displacement of walls, subsidence at the surface, axial forces, shear forces and bending moment on support systems and also time and costs were selected as main parameters in determining an optimum grouting radius. It was primarily aimed to calculate parameters of the Qazvin-Rasht railway tunnels using Finite Difference Method FLAC2D. In the next step, the values of selected parameters in various radiuses of grouting were calculated; then, the degrees of importance of each parameter were determined using Analytical Hierarchy Process. Finally, optimum grouting radius was selected among different alternatives by using VIKOR technique. In this study, 100 cm was selected as an optimal grouting radius for improving geomechanical and design parameters in KOUHIN tunnel.