基于改进XGBoost不平衡围岩超前分类方法的隧洞工程施工仿真研究

为了在围岩类别不平衡的条件下实现围岩类别有效判断，进而提高隧洞工程施工仿真准确性，基于改进极限梯度提升(XGBoost)不平衡围岩超前分类方法进行隧洞工程施工仿真研究。采用自动邻域确定合成过采样(AND-SMOTE)方法优化围岩类别不平衡性，并采用改进的XGBoost不平衡围岩超前分类模型进行围岩超前分类，进而优选仿真参数，提高仿真结果的准确性，其中，以模型交叉验证平均准确率为目标，采用哈里斯鹰优化(HHO)算法自动优化XGBoost超参数，以提高围岩分类精度。工程应用表明，相比未改进的XGBoost不平衡、KNN、SVC等6个模型，改进的XGBoost不平衡围岩超前分类模型分类精度更高；考虑围岩类别不平衡性后，改进的XGBoost不平衡围岩超前分类模型分类精度提高了8.6%;此外，基于围岩超前分类的隧洞工程施工仿真结果与实际进度的相对偏差相比传统仿真降低了11.3%,更符合工程实际。

Study on tunnel construction simulation based on advanced classification of imbalanced surrounding rock using improved XGBoost

In order to realize the effective judgment of surrounding rock classification under the condition of imbalanced surrounding rock classification and improve the simulation accuracy of tunnel construction, a study on the tunnel construction simulation is carried out based on the advanced classification of imbalanced surrounding rock with improved eXtreme Gradient Boosting (XGBoost). The Automatic Neighborhood size Determination-SMOTE (AND-SMOTE) method is used to optimize the class imbalance of surrounding rock, and the improved XGBoost model is used for advanced classification of surrounding rock, and then the simulation parameters are optimized, which improved the accuracy of tunnel construction simulation. In order to improve the accuracy of surrounding rock classification, the Harris Hawks Optimization (HHO) algorithm is used to automatically optimize the hyperparameters of XGBoost ensemble classifier. The engineering application shows that the improved XGBoost model has higher classification accuracy than the unimproved XGBoost, KNN, SVC and other 6 models. The classification accuracy of the improved XGBoost model is improved by 8.6% after considering the class imbalance of surrounding rock. In addition, the relative deviation between the results of tunnel construction simulation based on the advanced classification of surrounding rock and the actual progress is reduced by 11.3% compared with the traditional simulation, which is more in line with the engineering reality.