Damage analysis of tunnel bottom structure under high water pressure and high speed train dynamic load
The uplift and cracking in high-speed railway tunnels is caused by various factors.The discordant deformation mechanism of the tunnel invert under high hydraulic pressure and train dynamic load was investigated using the extended finite element method,fluid-solid coupling theory and field measurement results.The parameters of the surrounding rock were determined through displacement back analysis based on genetic algorithm using in-situ measured data.The causes and effects of train vibration load were simulated using the exciting force load function.The numerical simulation was employed to obtain the distribution of water pressure,as well as the characteristics of stress and deformation of the tunnel bottom structure under dynamic load.The results indicate that,based on the current tunnel bottom structure types and drainage conditions,water pressure changes are the main factor leading to deformation and cracking of the tunnel bottom structure.The tunnel bottom structure experiences sustained uplift and cracking due to the alternating variation of crack water pressure induced by train dynamic loads,which acts as an indirect cause.Micro-cracks initially appear at the center drainage ditch and then develop at each interface of the filling layer,the lining structure and the track plate due to the varying stiffness between them.The periodic vibration caused by the train dynamic load results in excessive hydrostatic pressure.These cracks undergo opening and closing under the wheel load,leading to a hydraulic fracturing effect that further compromises the integrity of the invert structure.In order to address the uplift and cracking in high water pressure and high-speed rail tunnel bottom structures,remediation measures should comprehensively consider water drainage and pressure reduction,crack sealing,and interlayer anchoring of the bottom multi-layer structure system.
万方数据
维普
