Study on the Triangulateration Network of Dynamic Benchmarks of Auto Total Station in Structural Health Monitoring

Nowadays,the auto total station has been used in dam/bridge/ tunnel real-time monitoring,due to its character of high precision and fast response.While more than one total station have to be arranged in de-formation areas,when large structures are complicated and the inner interlaced parts of large structures cause blocking of light beam.Unstable settlement of total stations may introduce measuring error.To address this problem,the dynamic observation stations(called as dynamic benchmarks) based on triangulateration network is presented.In this triangulateration network,more than two total stations are settled on unstable bases used as dynamic benchmarks,two total stations are arranged on stable benchmarks.Reflective prisms are installed on each total station,so that neighboring two total stations can see each other.Approximate coordinates of dy-namic benchmarks are calculated based on this triangulateration network observation.Accurate coordinates of them are obtained by adjustment.If coordinate difference of dynamic benchmarks between two observation peri-ods is less than a threshold(given by deformation range of structure),dynamic benchmarks are used as datum applied to measuring other measuring points.While,if difference between two observation periods is larger than the threshold,a compensation method is introduced to correct coordinate of measuring points.Further-more,observation simulation experiment is presented based on this principle.The experiment is carried out with one Leica TC 405 total station.The experimental results show that triangulateration network of dynamicbenchmarks method is correct and feasible.Coordinates error of measuring points using updating coordinate da-ta of dynamic benchmarks is less than 3 mm,Coordinates error by compensation method is about 5 mm.