| In recent years,with the rapid development of hydropower and dam construction,China has built many high dams in many rivers.Most of them almost have the height of 300 m.Everyone is proud of it.However,here comes a problem.Many of the high dams locate in southwest of China,where earthquakes occur frequently.We must pay more serious attention to it..Many domestic experts have studied anti-seismic issues.They have got certain achievements.Simply speaking,the high dam seismic design is to calculate the structural response under given seismic input.Modal calculation and dynamic structure test are the two main methods to study anti-seismic of high dams.As for modal calculation,due to huge structure,complex detailed structure and various environmental factors,it is difficult to build up the mathematical model,confirm the parameters and to find out the computing method.And for dynamic structure test,it is hard to simulate the real process.It is necessary to combine the results from modal calculation.Domestic prototype dynamic tests was only operated on a few dams in 1970 s.There were some valuable information,but in consideration of security and the test process,it is not suitable to apply those methods to nowadays` high dams.It is necessary to find another way for prototype dynamic tests on high dams.Ambient vibration tests are widely used to obtain the parameters of structural dynamic characteristics,such as bridges,buildings etc.Ambient vibration tests use wind,traffic as the source of vibration,to analyze dynamic characteristics.It is an available method so far.This thesis designs a set of online monitoring system for high dams based on ambient vibration tests.It consists of three parts: vibration detecting and data acquisition,wireless data transmission,data processing.After a series of work on systematic design,selection of instruments and tests,I went to Xiluodu Hydropower Station to build up the online monitoring system.In the end of this thesis,some results are obtained. |
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