Research On House Shutters Vibration Caused By Low Frequency Noise Induced By Xiangjiaba Flood Discharge

In China,the structure vibration,downstream scouring and atomization induced by flood discharge of high dam have been widely studied,while few studies have been done on the induced low frequency noise(lower than 10 Hz of air pulsation) and its environmental hazards so far.In view of the fact that low frequency noise has been actually measured in models and prototypes of Xiangjiaba and Jinping projects,and the possibility that the noise may cause environmental hazards such as the vibration of house doors and windows and the discomfort of residents to some extent in actual projects.Through field observations and model analysis,making study of the impact that low frequency noise has on residential buildings shutter doors vibration induced by Xiangjiaba discharge,and proposing a reasonable solution,to reduce the hazards caused by low frequency noise.Firstly, choose and emplace typical test points in the city Shuifu where Xiangjiaba lies,then carry on real-time monitor of low frequency noise on all test points,and use Matlab to analysis the result of the test,thus obtaining the low frequency noise pulsating pressure diagram and power spectral density plots,draw the effective value of low frequency noise in the distribution of space,analyze the rule how effective value and basic frequency of low frequency noise vary with the flow rate variation, and give the safety threshold of low frequency noise,to assess the main impact region of low frequency noise.Secondly,make use of the finite element software ANSYS to establish the shutter doors system model,and carry on finite element analysis to it:(1) modal analysis is carried out on the shutters,to calculate the natural frequencies and mode shapes,and analyze the possibility of shutter doors resonance;(2) carry on modal analysis on the shutter doors at different opening and different boundary conditions respectively,to simulate the effects that opening and boundary constraints have on self-vibration characteristics;(3) transient analysis of the shutters under different constraint conditions to simulate the vibration response of the shutter doors,and improve boundary conditions according to the simulation result,so as to reduce the shutter doors shaking,thus improving the dynamic characteristics of the system;(4) simulate the vibration response of shutter doors under different opening conditions to compare and analyze the dynamic characteristics;(5) simulate the shutter doors vibration response when taken different stiffness boundary,and analyze the effects that different stiffness boundary have on self-vibration characteristics.Thirdly,loading measured along-river displacement on the shutters reel of Yucai Road building 5 to simulate the shutters vibration caused by the structure of house vibration and comparing with the vibration of shutter doors under the effect of low frequency noise,to analysis how much do they impact on the shutter doors vibration phenomenon.The results show that low frequency noise is the main cause of shutter doors shaking.Finally,takes the plate as the example to simulate the impact that different sizes and different materials have on plate self-vibration and response characteristics,and analogy to the shutter doors,to obtain a preferred embodiment of the shutter doors,then gives some effective shock absorption and noise reduction measures,to improve the effect on the vibration of the shutter doors induced by low frequency noise.