Predication of Displacement of Tunnel Rock Mass Based on the Back-Analysis Method-BP Neural Network

Back-analysis can be regarded as the reverse process of forwarding analysis. The forward analysis in geotechnical engineering is to utilize the geometric dimensions, constitutive relations, material parameters, and boundary load conditions determined by the rock mass medium to solve the physical quantity information (strain, stress, Displacement) process. In this paper, a novel back analysis program based on BP neural network is proposed, which can realize automatic correction and adjustment of parameters and adapt to most tunnel projects. Subsequently, the analysis program is applied to the front and back joint modeling of the Nagasaki tunnel project. The mechanical parameters and initial stresses of the back analysis are utilized to conduct finite element calculations, and the displacements of all monitoring points of the multi-point displacement measurement are calculated. The results are in good agreement with the measured values. The proposed back-analysis method in this paper can also be applied to the determination of other tunnel rock mass parameters.