The pseudo-excitation method combined with the integral transform method (PEM-ITM) is presented to investigate the ground vibration of a coupled track-soil system induced by moving random loads. Commonly in the track ...The pseudo-excitation method combined with the integral transform method (PEM-ITM) is presented to investigate the ground vibration of a coupled track-soil system induced by moving random loads. Commonly in the track model, the rail, sleepers, rail pads, and ballast are modelled as an infinite Euler beam, discretely distributed masses, discretely distributed vertical springs, and a viscoelastic layer, respectively. The soil is regarded as a homogenous isotropic half-space coupled with the track using the boundary condition at the surface of the ground. By introducing a pseudo-excitation, the random vibration analysis of the coupled system is converted into a harmonic analysis. The analytical form of evolutionary power spectral density responses of the simplified coupled track-soil system under a random moving load is derived in the frequency/wavenumber domain by PEM-ITM. In the numerical examples, the effects of different parameters, such as the moving speed, the soil properties, and the coherence of moving loads, on the ground response are investigated.展开更多
The dynamic behaviour of slab and ballast tracks was investigated using measurements and calculations.Hammer impacts and train passages were analysed and measurements were made using geophones(velocity transducers)whi...The dynamic behaviour of slab and ballast tracks was investigated using measurements and calculations.Hammer impacts and train passages were analysed and measurements were made using geophones(velocity transducers)which had been time-integrated to displacements.The calculations were carried out in the frequency-wavenumber domain for multi-beamon-continuous soil models.The characteristics of the different tracks and track elements were established in theory and by experiment.The frequency-dependent compliances(displacement transfer functions)showed clear rail-on-railpad resonances or highly damped track-soil resonances.Compared to the rail and sleeper,the track slab had much lower amplitudes.The slab track usually had the highest rail amplitudes due to soft railpads.Train passage yielded track displacements which were a superposition of the axle loads from the two neighbouring axles of a bogie and from the two bogies of two neighbouring carriages.This global behaviour was characteristic of the track slab of the slab track,whereas the rails of the slab and the ballast tracks behaved more locally with only one bogie of influence.The measurements agreed very well with the theory of continuous soil in the case of the six measured slab tracks and acceptably well for the six measured ballast tracks.The measurements allowed us to find appropriate model parameters and to check the models.For example,the Winkler model of the soil was found to be less appropriate because it reacted more locally.展开更多
Deep-sea mining has emerged as a critical solution to address global resource shortages;however,the mechanical interaction between tracked mining vehicles(TMVs)and soft seabed sediments presents fundamental engineerin...Deep-sea mining has emerged as a critical solution to address global resource shortages;however,the mechanical interaction between tracked mining vehicles(TMVs)and soft seabed sediments presents fundamental engineering challenges.This study establishes a multiscale modelling framework coupling the discrete element method(DEM)with multi-body dynamics(MBD)to investigate track-seabed dynamic interactions across three operational modes:flat terrain,slope climbing,and ditch surmounting.The simulation framework,validated against laboratory experiments,systematically evaluates the influence of grouser geometry(involute,triangular,and pin-type)and traveling speed(0.2–1.0 m/s)on traction performance,slip rate,and ground pressure distribution.Results reveal rate-dependent traction mechanisms governed by soil microstructural responses:higher speeds enhance peak traction but exacerbate slip instability on complex terrain.Critical operational thresholds are established—0.7 m/s for flat terrain,≤0.5 m/s for slopes and ditches—with distinct grouser optimization strategies:involute grousers achieve 35%–40%slip reduction on slopes through progressive soil engagement,while triangular grousers provide optimal impact resistance during ditch crossing with 30%–35%performance improvement.These findings provide quantitative design criteria and operational guidelines for optimizing TMV structural parameters and control strategies,offering a robust theoretical foundation for enhancing the performance,safety,and reliability of deep-sea mining equipment in complex submarine environments.展开更多
基金the National Basic Research Program of China (Grant 2014CB046803)the National Natural Science Foundation of China (Grant 11772084).
文摘The pseudo-excitation method combined with the integral transform method (PEM-ITM) is presented to investigate the ground vibration of a coupled track-soil system induced by moving random loads. Commonly in the track model, the rail, sleepers, rail pads, and ballast are modelled as an infinite Euler beam, discretely distributed masses, discretely distributed vertical springs, and a viscoelastic layer, respectively. The soil is regarded as a homogenous isotropic half-space coupled with the track using the boundary condition at the surface of the ground. By introducing a pseudo-excitation, the random vibration analysis of the coupled system is converted into a harmonic analysis. The analytical form of evolutionary power spectral density responses of the simplified coupled track-soil system under a random moving load is derived in the frequency/wavenumber domain by PEM-ITM. In the numerical examples, the effects of different parameters, such as the moving speed, the soil properties, and the coherence of moving loads, on the ground response are investigated.
文摘The dynamic behaviour of slab and ballast tracks was investigated using measurements and calculations.Hammer impacts and train passages were analysed and measurements were made using geophones(velocity transducers)which had been time-integrated to displacements.The calculations were carried out in the frequency-wavenumber domain for multi-beamon-continuous soil models.The characteristics of the different tracks and track elements were established in theory and by experiment.The frequency-dependent compliances(displacement transfer functions)showed clear rail-on-railpad resonances or highly damped track-soil resonances.Compared to the rail and sleeper,the track slab had much lower amplitudes.The slab track usually had the highest rail amplitudes due to soft railpads.Train passage yielded track displacements which were a superposition of the axle loads from the two neighbouring axles of a bogie and from the two bogies of two neighbouring carriages.This global behaviour was characteristic of the track slab of the slab track,whereas the rails of the slab and the ballast tracks behaved more locally with only one bogie of influence.The measurements agreed very well with the theory of continuous soil in the case of the six measured slab tracks and acceptably well for the six measured ballast tracks.The measurements allowed us to find appropriate model parameters and to check the models.For example,the Winkler model of the soil was found to be less appropriate because it reacted more locally.
基金financially supported by the National Key Research and Development Program of China-Young Scientist Project(No.2024YFC2815400)the National Natural Science Foundation of China(No.52588202).
文摘Deep-sea mining has emerged as a critical solution to address global resource shortages;however,the mechanical interaction between tracked mining vehicles(TMVs)and soft seabed sediments presents fundamental engineering challenges.This study establishes a multiscale modelling framework coupling the discrete element method(DEM)with multi-body dynamics(MBD)to investigate track-seabed dynamic interactions across three operational modes:flat terrain,slope climbing,and ditch surmounting.The simulation framework,validated against laboratory experiments,systematically evaluates the influence of grouser geometry(involute,triangular,and pin-type)and traveling speed(0.2–1.0 m/s)on traction performance,slip rate,and ground pressure distribution.Results reveal rate-dependent traction mechanisms governed by soil microstructural responses:higher speeds enhance peak traction but exacerbate slip instability on complex terrain.Critical operational thresholds are established—0.7 m/s for flat terrain,≤0.5 m/s for slopes and ditches—with distinct grouser optimization strategies:involute grousers achieve 35%–40%slip reduction on slopes through progressive soil engagement,while triangular grousers provide optimal impact resistance during ditch crossing with 30%–35%performance improvement.These findings provide quantitative design criteria and operational guidelines for optimizing TMV structural parameters and control strategies,offering a robust theoretical foundation for enhancing the performance,safety,and reliability of deep-sea mining equipment in complex submarine environments.
