Prediction of ground settlement and the corresponding risk induced by tunneling: An application of rock engineering system paradigm

Abstract

A new Ground Settlement Index (GSI) to evaluate the ground movements due to tunneling is proposed. Fifteen parameters that are effective on tunneling-induced settlements are employed for the GSI introduction. The corresponding weights and interactions between the parameters are also computed based on the context of the Rock Engineering Systems (RES) methodology. Results indicate that the selected parameters have great significance to ground settlement owing to tunneling. Advance rate, height to weight ratio and closure of tunnel lining, among other parameters, are found to be more influential in GSI. The risk levels associated with ground settlement were classified based on GSI values, showing no case history of highly hazardous settlement. The data for 42 monitoring points, located at ventilation tunnel of Air Exchange Station Project, Iran, were utilized to develop the RES based model for predicting vertical ground settlement. For comparison purpose, numerical analysis, as a key instrument for tunnel safety analysis, was also employed for estimating ground settlement. For validation purpose, the ground settlements of other nine points were measured and the obtained values were compared with those predicted by both RES and numerical models. The performances of the proposed predictive models were calculated by two performance indices, coefficient of determination (R2) and less root mean square error (RMSE). The obtained results of this study show that the RES predictive model with higher R2 and less RMSE performs better than the numerical analysis.