Study On Wind-induced Vibration And Mechanical Properties Of High-speed Rail Fully Enclosed Acoustic Barrier Trains

The fully enclosed sound barrier has the best effect among the current traffic noise reduction measures,and it has been paid more and more attention with the economic development.However,due to the formation of "piston wind" when the train passes through,its aerodynamic impact on the fully enclosed sound barrier is much larger than that of the semi-closed and upright type.Especially in recent years,the speed of my country’s high-speed railways has been increasing.The pulsating wind-induced vibration of the train is likely to cause fatigue damage to the fully enclosed sound barrier structure,resulting in huge safety hazards.At present,the research on the vehicle-induced pulsating wind pressure and structural vibration response of the fully enclosed sound barrier is not enough.In this paper,based on the fully enclosed sound barrier of the Beijing-Xiong Intercity High-speed Railway,a finite element flow field model and a structural model are established to study the vehicle-induced pulsating wind pressure,structural dynamic response and fatigue performance of the sound barrier.The main contents are as follows:(1)Based on the computational fluid dynamics analysis method,the numerical model of the train,the fully enclosed sound barrier and the fluid domain is established,and the FLUENT software is used to simulate the flow field.The pulsating wind pressure on the wall of the sound barrier.Then refer to the train set dynamic model test to verify the rationality of the model.The results show that the error between the numerical simulation results and the dynamic model test results under the four working conditions is within 15%,and the numerical model can reflect the aerodynamic impact of the pulsating wind on the structure when the train passes through the fully enclosed sound barrier at high speed.(2)Summarize the distribution law of the pulsating wind along the longitudinal and lateral directions when the train passes by a single vehicle at 350 km/h and when the sound barrier intersects,and explore the time-history curve of the pulsating wind at different vehicle speeds(250 km/h,300 km/h,350 km/h).The effect of period and amplitude.The results show that: when a single vehicle passes,the pulsating wind curve presents the form of crest-valley-peak;when the train crosses,the curve of the entrance and exit measuring points presents the form of peak-valley-valley-peak,and the curve of measuring points near the middle section presents peak-valley-peak.form.The fluctuating wind curves of the same section measuring point are highly overlapped under different working conditions.The increase of the vehicle speed will cause the change period of the pulsating wind time-history curve to decrease,and the wind pressure amplitude will change twice.(3)The overall finite element model of the fully enclosed sound barrier is established,and the simulated wind pressure time-history load results are applied to the wall of the sound barrier to obtain the transient dynamic response of the sound barrier unit plate and steel arch,and determine the weak parts of the structure.The results show that when the train passes through the model area,when the structure is subjected to negative pressure,the dynamic response increases and shrinks inward as a whole;as the train leaves,the structure is subjected to positive pressure,and the dynamic response weakens and expands outward as a whole.The maximum position of structural stress occurs near the column base during the running process of the train.(4)A refined finite element model of the column base was established,and the static loading simulation results were compared and verified with the static loading test.Then,the load internal force time history near the column base under the action of pulsating wind was applied to the column base fine model to carry out fatigue analysis.The results show that the stress level of the column foot web is the highest,followed by the upper and lower flanges,and the U-bolt is the lowest.The cyclic stress spectrum shows that the full cycle amplitude of the FY stress is 47105 N,the cycle is 1 time,and the average value is-6348 N,which is the main fatigue load.During the fatigue loading,stress concentration may occur at the connection position of the bolt and the bottom plate,which is earlier than the other parts of the steel column foot.Fatigue damage occurred in the parts,but the safety factor of fatigue damage was still above 2.5,and the durability and safety of the structure met the requirements.