# Research on an Evaluation Method for the Adaptability of TBM Tunnelling
## 1 Introduction  
Due to the requirements of infrastructure construction and the implementation of the \"One Belt, One Road\" strategy, large-scale water diversion, railway, and highway tunnel projects are becoming more and more common in China. With the increase in buried depth, longer tunnelling distances, and more complex geological conditions, the larger section size, more-demanding construction period, and cost requirements are becoming the development direction of tunnel construction in China. For example, the open TBM used in hydraulic engineering in Xinjiang caused large fault fracture zones, rock bursts and water intrushes during tunnelling, resulting in equipment jamming and delaying the construction period for up to half a year. Another example is the Gaoligongshan tunnel project in Yunnan, China, which adopts the open-TBM construction method; due to poor geological conditions, there are a large number of fault fracture zones with different scales, and the problem of high geotemperature is prominent, resulting in extremely poor TBM construction conditions and slow excavation [1]. An open TBM was used in the construction of an S tunnel during hydraulic engineering in Japan. Due to insufficient geological surveying in the early stage and wrong judgments on the tunnelling adaptability of the TBM, the TBM was affected by the large deformations of the surrounding rock inthe tunnelling process, and machine jams occurred frequently. Finally, a TBM can only be removed and used for the shield tunnelling of the remaining projects [2]. The main reason for the serious construction consequences outlined above is the lack of systematic and quantifiable TBM tunnelling adaptability evaluation methods and theories. Therefore, the research on an evaluation method of TBM tunnelling adaptability under complex geological conditions has become a large problem that needs to be overcome in the construction of long tunnels in the fields of water conservancy, railways, and highways. TBM tunnelling involves massive amounts of data, such as on the surrounding rock deformations, electromechanical control, cutter rock breaking, geological disasters, and construction safety, from advanced exploration to design to tunnelling, which provide a stage for the application of fuzzy comprehensive evaluation. The fuzzy mathematics theory can describe and model a large number of fuzzy concepts and fuzzy phenomena in the real world with precise mathematical means, so as to achieve the purpose of proper processing [3]. In order to solve the uncertainties of geological and geotechnical parameters, [PERSON] et al. have adopted the method of fuzzy hierarchy analysis to pre-judge the selection adaptability of different TBMs under adverse geological conditions [4]. In order to predict the specific energy demand of a TBM, [PERSON] constructed a TBM-specific energy prediction method based on a fuzzy logic model [5]. [PERSON] built a new resource model based on the tunnel-assisted decision-making system DAT, which optimizes the allocation and planning of tunnel resources [6]. In addition, in order to identify the risks of TBM tunnelling and provide a clear roadmap for possible measures, [PERSON] et al. proposed a new risk analysis method, which is based on a generic bow-tie method and integrates fault tree and event tree analysis methods, which can be used to systematically assess and manage TBM-related risks under difficult ground conditions [7]. Therefore, the application of the fuzzy theory to TBM tunnelling adaptability evaluation is the current development trend. This can not only improve the construction level of TBM tunnel engineering but also avoid engineering accidents caused by unsuitable TBM tunnelling to a certain extent, as well as promote more efficient, scientific, and systematic decision-making evaluations of TBM tunnelling adaptability.