Acta Montanistica Slovaca Volume 20 (2015), number 2, 98-109 98 Selection of tunneling machines in soft ground by fuzzy analytic hierarchy process M. Kemal Ozfirat 1 In tunneling, it is very important to select the correct tunneling machines. Choosing a wrong method may be very costly to the company. There are many parameters affecting the decision stage of selection of the tunneling machine. Geology (C1), ground conditions (C2), tunnel properties (C3), geo-environmental hazard (C4), technical properties of machines (C5), and project properties (C6) are the main selection criteria. Using these topics and the sub-criteria belonging to each topic, the fuzzy analytic hierarchy method is employed to select the most suitable tunneling machine. Tunnel boring machines are mainly divided into two as hard and soft ground machines. The number of tunnels under cities constitute a large amount due to subways, underground roads, etc. These tunnels are mostly shallow tunnels. Therefore, the variety of soft ground tunneling machines increase. In this research, soft ground type machines and their parameters are evaluated. After evaluation with the fuzzy analytic hierarchy process, geology (C1) turned out to be the factor most influencing the selection of machine type, and M3 (EPBM) is found to be the most suitable machine for soft ground conditions. In addition, the research method and the study results are thought to be helpful in selecting the machine type for other tunnels which will soon be started in Turkey. Key words: Tunneling, Soft ground, Fuzzy logic, Machine selection, Excavation. 1. Introduction Subway tunneling evolved in recent years in order to ease city traffic and, therefore, progress has been made on the soft ground machine types and diversity. Subway tunnels are generally shallow tunnels. That is why ground conditions should be taken into consideration carefully. Langmaack and Seven (2007) and Köse et al. (2007) mentioned that the three most important factors for soft ground tunneling, apart from the hard rock geology, are the soil permeability, ground water pressure, risk of clogging and adhesion. There are many parameters affecting the decision stage of selection of the tunneling machine. Geology (C1), ground conditions (C2), tunnel properties (C3), geo-environmental hazard (C4), technical properties of machines (C5), and project properties (C6) are the main selection criteria. In this study, soft ground is studied and the corresponding machine types are investigated. Selection criteria are determined with the help of many different references from the literature. This section will be explained in Chapter 2. Alternative machines are selected according to the ITA (2000). These machines are the shield type (M1), the mechanical excavation type (M2), the earth pressure balance type (M3), slurry type (M4), hand excavation (M5), semi-mechanical excavation (M6), blind type (M7), roadheader (M8), and hydraulic hammer (M9), respectively. These criteria are evaluated by a fuzzy analytic hierarchy process (FAHP) and an application is made on an example case. The objective of this fuzzy analytic hierarchy process problem is to select the most suitable machine for the tunnel under study. The study aims to determine the best machine for Izmir (Turkey) subway tunnel as given in Figure 1. Fig. 1. Hierarchy of the selection process. 1 M. Kemal Ozfirat, Dokuz Eylul University, Engineering Faculty, Mining Eng. Dept., Tinaztepe Campus, Buca-Đzmir-TURKEY, Tel/Fax: +902323017539/+902324530868, kemal.ozfirat@deu.edu.tr