Real-Time Updated Risk Assessment Model for the Large Deformation of the Soft Rock Tunnel

Large deformation of the surrounding rock is a common geological hazard when excavating a new tunnel to be driven through soft rock, and this occurrence can severely interrupt the construction schedule and affect the safety of tunnel engineering. Therefore, it is important to study the risk level prediction for large deformation of the soft rock tunnel. Thus, this paper developed and examined a real-time (immediately) updated model. The model can parameterize for use in predicting levels of risk of large deformation of soft rock tunnel projects based on fuzzy multiattribute decision-making (FMADM). Two real field-based deformation indicators and 3 first-level evaluation indicators, including the 14 second-level indicators, were collected for data. Each indicator was quantitatively graded into four levels of risk of large deformation based upon the expert evaluation system for classification. Furthermore, a real-time updated comprehensive weight of each assessment indicator was presented from results using the analytic hierarchy process (AHP) and the entropy weight method (EWM). After that, a real-time updated risk assessment model was established by the use of the development of fuzzy membership functions. This risk assessment model was applied to five soft rock tunnel projects, and the corresponding model-based evaluated results were consistent with the real deformation degree based upon field measurement. This model could be used as new and well-defined sets of guidelines for improving the understanding of risk-based assessments of the potential for large deformation of the soft rock tunnel.