Prediction Analysis of Settlement of Existing Road Under Shield Tunneling Based on IPSO-SVR

At present, there are relatively few studies on the settlement prediction of shield tunnels crossing existing roads in parallel. To accurately predict the influence of different factors on the settlement of existing parallel roads in the shield process, this study proposed a support vector regression prediction model based on the improved particle swarm optimization (IPSO-SVR), which was applied to the surface road settlement prediction of actual subway tunnel engineering. Based on the Changchun Metro Line 6 under-crossing Feiyue Road section project, combined with the shield boring parameters, formation information and road settlement monitoring during the construction of the shield tunnel, this paper used the grid search method of libsvm to reduce the range of hyperparameters, and improved the change of inertia weight and acceleration factor in particle swarm optimization algorithm by combining the nonlinear decline strategy. Finally, IPSO-SVR prediction model was established to achieve the settlement prediction of subsequent sections in the interval. The results show that, comparing the changes of the objective function (mean square error) in the grid search method and in the conventional particle swarm optimization training, the convergence speed of the improved particle swarm optimization is greatly improved; the convergence effect of the objective function is better, and the minimum value is reduced by nearly 15%. The mean absolute error (MAE) of IPSO-SVR prediction of road settlement proposed in this paper is 0.287, the fitting coefficient R² is 0.884, and the average relative error is only 8.91%, which has better performance than back propagation (BP) neural network, support vector regression (SVR) and particle swarm optimization support vector regression (PSO-SVR) prediction models. It can be seen that IPSO-SVR has high precision for nonlinear prediction of multi-factor coupling under complex conditions, and its prediction method is feasible and generalizable. IPSO-SVR can provide a reliable basis for effective control of road settlement and is of great significance for ensuring the normal operation of roads and the safety of shield construction.