An isoparametric element permutation method for railway tunnel–soil interaction modeling in train–track–tunnel–soil dynamic analysis

For evaluating the ground vibration involving metro tunnel operation, it is of necessity to extend the train-track-tunnel near-filed vibration to the train-track-tunnel-soil far-filed vibration in viewpoint of numerical analysis. It therefore becomes a key technology to achieve the tunnel-soil coupling simulation. In this work, a isoparametric element permutation method is proposed, where the 6-node triangular prismatic elements and 8-node spatial isoperimetric elements have been effectively integrated to achieve the finite elemental modelling of the soil system with the tunnel penetrating. The tunnel and soil subsystems are coupled by the spring-dashpot elements. Once the tunnel satisfies symmetrical property in geometry, the proposed method can be applied to build the tunnel-soil interaction by parametric finite element modelling. Through a combination of this proposed tunnel-soil interaction model and the train-track-tunnel dynamic model, a unified model for characterizing the train–track–tunnel–soil dynamic interaction analysis is constructed within the finite element framework. By comparing the simulation results to the measurements in site, the effectiveness of this model is validated, through which track, tunnel, and ground vibrations can be assessed in an entirely coupled way. Through the numerical studies, it is known that both the number of tunnel lines and the number of trains in operation and their running modes hold significant influence and show different vibration attenuation law on ground vibrations, and quantitative analysis can be achieved through this present work.