Study Of Positioning Methods With Precise Three-Dimensional Coordinates For Long-span Bridge Construction Control

The total-station instrument changes traditional survey way of thinking, direct measures three-dimensional coordinates of point space The horizontal positioning accuracy of total-station instrument can generally satisfy demand for application, but make use of always is an extensively studying of everyone. The text put great emphasis on the research to increase positioning accuracy's theories and methods of total-station instrument's triangle elevation from the positioning accuracy of total-station instrument analysis.First, in the horizontal positioning accuracy aspect of total-station instrument, point out the importance of direction, distance to correct calculation and coordinates to convert, give coordinates calculated formula of single intersection point of non-symmetry type of horizontal curve, deduce to square-error's calculated formula of horizontal coordinates and point space by polar coordinates positioning methods, and analyze the main influence factor of square-error.The next in order, in the triangle elevation positioning accuracy aspect of total-station instrument, atmospheric refraction coefficient is considered time and direction variable, depend on elevation difference and deformation calculated formula of single > reciprocal and midpoint observation by total-station instrument's triangle elevation, and deduce to square-error's calculated formula of elevation difference and deformation, and analyze detailed and discuss deep square-error.Furthermore, the variety characteristics according to the atmospheric refraction, deduce to square-error's calculated formula of atmospheric refraction coefficient, analyze the main influence factor to affect measuring accuracy of atmospheric refraction coefficient. Input for network with the geography time> air temperature and press, output atmospheric refraction coefficient, established the neural network modelof atmospheric refraction coefficient, and realize its real-time correction To realize valid real-time correct of atmospheric refraction coefficient, become the key to increase positioning accuracy of total-station instrument's triangle elevation.Finally, join together rib-hoisting construction of Nanlidu long-span bridge, and the circumstance with ground thing, geography and geology, establish the alone bridge construction control network of three-dimensional coordinates, and adopt practical and viable precise position of the whole rib-hoisting process by single observation of polar coordinates, still establish network model of rib-elevation and flexible cable force.With total-station instrument approaching perfection day-by-day, three-dimensional coordinate methods of total-station instrument with precise is used to position in bridge construction. The precision got by this way may satisfy demands for standards of testing and judging bridge quality. Moreover, surveying links can be simple and surveying time can be reduced. By this way, therefore, the pace of bridge construction can be quick greatly.