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清水河大桥主跨1 130m,地处多雨、多雾的黔中高原,桥位处峡谷两岸地势陡峭,地形变化急剧,起伏很大。为保证基准索架设的精度,分析了单向三角高程的误差来源和精度;充分利用了山区特有的地形,将测量控制点布置在最有利的位置,从点位分布的角度上,减少单向三角高程的测量误差;测量垂度时采用了特制的六边形夹具棱镜组,大大减小了立棱镜的人为误差;测距时进行了大气折光系数、距离归化等多项改正,保证三角高程测量精度。以上方法在实际应用中取得了较好的效果,可供同类型桥梁工程借鉴。
The main span of Qingshuihe Bridge is 1 130m, located in the rainy and foggy Qianzhong Plateau. The bridge is steep at both sides of the canyon. The terrain changes rapidly and fluctuates greatly. In order to ensure the accuracy of datum setting, the source and accuracy of error of unidirectional trigonometric elevation are analyzed. Taking full advantage of the unique topography of mountainous area, the measurement control points are arranged in the most favorable position. From point distribution point of view, Triangular elevation measurement error; the use of a special hexagonal fixture prism set to measure the sag, greatly reducing the prism error of man-made error; rangefinder when the atmospheric refraction coefficient, the distance of a number of naturalization and other amendments to ensure triangular Elevation measurement accuracy. The above method has achieved good results in practical applications, for the same type of bridge project reference.