A surrogate model for the rapid prediction of rockburst risk based on numerical samples and random forest classifier
[Objective]This study aims to address the significant challenge of predicting rockburst risks during the excavation of deep tunnels using tunnel boring machine(TBM)tunnel boring machine and develop a rapid prediction model to provide the basis for rockburst prevention and control,enhancing the safety and efficiency of deep tunnel construction.The proposed model leverages numerical samples and random forest(RF)algorithms to overcome the limitations of existing methods,which often do not achieve real-time and rapid prediction or consider the underlying mechanisms and factors influencing rockbursts.[Methods]Considering the Xianglushan Tunnel within the Dianzhong Water Diversion Project,we introduced a model that utilizes geostress and rock constitutive parameters as inputs and the elastic strain energy density of the surrounding rock as output.Numerical simulations of tunneling using the TBM under various working conditions arewere conducted,and 611 numerical samples were crafted through an orthogonal experimental design.We employed RF as the underlying classifier,with hyperparameters optimized through 10-fold cross-validation to create an efficient prediction model.The accuracy and applicability of the model were confirmed by comparing several machine learning algorithms.[Results]We conducted a series of numerical simulations of excavation using the TBM,employing an elastoviscoplastic constitutive model with internal variables.These simulations disclosed the energy evolution within the rock mass throughout the excavation process.Energy concentration occurred during transient unloading and the time-dependent deformation of the surrounding rock,leading to two distinct peaks in strain energy density.The second peak indicative the final energy storage during the creep phase of the surrounding rock postexcavation and unloading.Notably,a higher value at the tunnel wall—under identical conditions—correlated with an elevated risk of strainburst.We verified the rationality of the input and output parameters by analyzing energy evolution and correlation.The predictive accuracy and computational efficiency of the model were enhanced following the optimization of the hyperparameters using a 10-fold cross-validation.The input parameters partially mirrored the factors influencing rockburst,while the output parameters measured the energy storage status of the surrounding rock before potential rockburst failure.The RF-based rockburst risk prediction proxy model exhibited commendable performance on the training and testing sets,achieving accuracies of 99.75%and 82.02%,respectively.The performance of the RF-based rockburst risk prediction proxy model was superior to that of four other machine learning models—decision tree,K-nearest neighbors,support vector machine,and logistic regression—achieving prediction accuracies of 82.02%,76.40%,79.77%,75.28%,and 76.40%for all samples,respectively.This result indicateds the robust predictive capability and generalization performance of the RF-based rockburst risk prediction proxy model in assessing rockburst risk levels.[Conclusions]We offer a novel approach and framework for the rapid prediction of rockburst risks during the excavation phase of deep tunnels.The RF-based rockburst risk prediction proxy model is reportedly an effective tool for rockburst risk prediction,marking a significant advancement in rockburst risk management.We provide a research path and framework for the rapid prediction of rockburst risk during the excavation period of deep tunnels.
deep tunnelrockburst risktunnel boring machinenumerical samplesrandom forestelastic strain energy