Experimental Research On Deloading Characteristics Of The V-Shaped Deloading Noise Barrier Applied To High-speed Railway

With the increase of train speed,the noise pollution caused by high-speed trains is becoming more and more serious,which brings great trouble to the life of the residents along the line.The conventional noise barrier can reduce the noise to a certain extent,but the intense aerodynamic load caused by the passing high-speed train acts on its surface and does harm to the structural solidarity and reliability of the noise barrier and threatens the safety of train transportation.As the results of related theoretical analysis and numerical simulation show,the deloading noise barrier performs well both in noise reduction and load shedding,which provides a method for solving the problem mentioned above.This paper focuses on the field test about the deloading characteristics of the deloading noise barrier relative to the general noise barrier.The main contents of this research are as follows.First,the set up of the test system was studied.According to the specific content of the test and relative test theory,the proper software and hardware composing the test platform were picked out then calibrate dand debugged to verify that the test platform to meet the requirements of this field test.Second,the layout of the three kinds of sensors was determined.In order to investigate the deloading characteristics of the V-profiled noise barrier,the layout scheme was vertified and modified repeatedly to make sure that the field test can be carried out reasonably and successfully.Third,the deloading characteristic of fluctuating pressure was investigated.In the time domain,the inindicators of inpact strength and pressure deloading rate were defined.The change of fluctuating pressure impact strength and pressure deloading rate versus speed and train modelwas studied and their vertical vertical distribution on the surface of noise barriers were investigated from the perspectives of peak,trough and the difference between peak and trough of the first wave.Fourth,the strain deloading characteristics was investigated.The indicaors of strain change rate and deloading rate were adopted or defined.The change rate of strain at the top of reinforced rib which impacts structural stability of noise barriers and the peak-trough deloading rate of strain were investigated from perspectives of head wave and coda wave;comparisive analogy on the shapes and values of strain waves at the roots of conventional and deloading niose barrier was conducted;the effect of the height of noise barrier and the distance between the noise barrier and the train on the strain deloading characteristic were explored too.Fifth,the displacement deloading characteristics were investigated.In the time domain,the indicator of displacement deloading rate was defined.The impact of speed and train model on the displacement at the top of steel pillar and in the middle of unit plate as well as deloading rate were studied;comprehensive analogy was carried out on the of pressure,strain and displacement deloading rate.Sixth,In the frequency domain,the impact of train speed,train model and special location on the change of fluctuating pressure spectrum was studied to determine the range in which the amplitudes of fluctuating pressure were larger.The Fourier transform was conducted to the signal of acceleration to figure out the he first-order natural frequency of sound barrier and its board.Comprehensive comparison was conducted to make judgment about the vibration of sound barrier providing support and supplement necessary for the study of deloading characteristics.