Theoretical Model And Prediction Method For Environmental Vibration Induced By Train Moving On Underground Railway

Due to advantages of velocity and punctuality,safety and comfort,environmental protection,wide coverage and large transportation volume,the urban rail transit(URT)has developed rapidly in many countries.The URT has been put into operation in more than 40 cities in China,and both operating mileage and the scale of passenger flow have situated at first in the world,and even the long-term planned mileage is up to 35,000 kilometers.With the increasing density of line networks and improving requirements for travel convenience and efficiency,the URT is getting closer to buildings,and the traffic volume and train speed become higher.However,the induced negative effects also become more evident,such as environmental vibration,uneven settlement of the line foundation,deformation of the line structure and even structural damage of track and infrastructure.Especially in recent years,many cities have developed the URT in the mode of transit-oriented development(TOD),which further exacerbate these probelms.The moving train induced vibration is the key factor for these problems.Therefore,it is significant to carry out research on theoretical models and prediction methods about train-induced vibration for improving line planning and environmental impact prediction,perfecting infrastructure design theory and maintenance technology and further clarifying the selection basis of vibration reduction and isolation measures for track system.The moving train induced vibration is studied in this dissertation,according to the following thinking of research: regarding the vehicle dynamics,track dynamics,tunnel-soil system dynamics as the foundation,regarding wheel/rail interactions and track-tunnel interactions as the relation,and regarding the train,tracks,tunnel and soil as a whole system,a train-track-tunnel-soil coupled dynamics model is proposed.On this basis,moving train induced vibrations of the large-scale building constructed on the subway are studied,using a more detailed three-dimensional finite element model of the tunnel-soil-building system with well considering the influences of the structure,geometrical dimensions and dynamic parameters of the building.The validity and perfection degree of the train-track-tunnel-soil coupled dynamics model play a decisive role in the reliability and accuracy of the simulation results.At first,a relative complete vehicle dynamics model is established in this dissertation.In the model,the vehicle is simplified as a multi-rigid-body system with primary and secondary suspension systems.All kinds of movements of the car body,boige frames,wheelsets and axle boxes and nonlinear factors in suspension systems are fully considered.Secondly,the spatical dynamics models for track systems with monolithic and slab track bed are established.In the model,the rails are regarded as Euler beams supported by discrete fasterners,and two dynamics models of slab are established,respectively based on the Kirchohhff elastic thin plate theory and the general theory of medium-thick plate vibration.Then,considering the influence of the track foundation and the tunnel grouting area,a composite multilayer cylindrical shell model and a semi-analytical/semi-numerical cylindrical layer element are developed,and on this basis,two dynamics models of tunnel-soil system are established.Finally,the wheel/rail interactions and the track-tunnel interactions are used to couple the vibrations of the train,track,tunnel and soil,forming the train-track-tunnel-soil coupled dynamics model.The track irregularities are taken as the excitations,and a multi-step explicit and implicit hybrid time integration method is used to solve the vibrations of the entire system.According to the established model,a dynamics simulation program named TTTSSIM is developed.The accuracy and reliability of the established model and the developed program TTTSSIM are verified,through a comprehensive comparison with commercial software SIMPACK,indoor full-scale floating slab track test,field hammering test and field measurement results from line operation.Using numerical experiments,some key modelling parameters of the tunnel-soil system are determined.Then,the influences of line status and train speed on the vibrations of tunnelsoil system and dynamic soil stresses induce by moving train are studied using TTTSSIM.Based on the train-track-tunnel-soil coupled dynamics model,the moving train induced building vibrations are predicted in an actual engineering project of a large-scale building constructed on the subway.The results are systematically and comprehensively evaluated according to relevant standards,and the vibration reduction effects of base isolation system are evaluated.