| CPâ…¢ control network is the plane and height datum of laying and operation and maintenance of the high-speed railway tracks. All the plane and elevation of CPâ…¢ can be obtained through observation length and angle by total station with free-station, but, CPâ…¢ elevation is measured by leveling in the practical application. Therefore, not all the observation data obtained by CPâ…¢ surface measurement can be got effective use. This do waste the measured data and reduce the work efficiency. In order to improve the efficiency of CPâ…¢ elevation control network, it needs to make statistical analysis of practical precision for CPâ…¢ trigonometric leveling. In addition, gross error is inevitable in the process of CPâ…¢ trigonometric leveling because of the large amount of data collection. If the gross error cannot be got rid of before the least squares adjustment, the adjustment results will inaccurate and the statistical results will produce deviation. Therefore, it needs to detect the gross error in measured data before the statistical analysis.In view of the above situation, firstly, this paper uses the simplex algorithm of the L-1 norm to detect the gross error in the trigonometric leveling data. Through the experiments of the measured data by CPâ…¢ trigonometric levelling on free-station of a period of high speed railway about 1000 km route., and comparing with the results of the least-square method. The engineering experimental results show that the simplex method can accurate positioning and fix value to the existing gross error in observations, and it is superior to the least square method. The measured data shows at the same time, the zenith-angle observations exist error which have a large effect on CPâ…¢ trigonometric leveling, and present as systemic effects. Therefore, this paper puts forward two kinds of methods of the zenith-angle observations correction, the unilateral leveling method and the zenith distance correction method. The first method correct the zenith-angle observations of triangular elevation station through leveling the unilateral control points of the CPIII control network. The second method directly calculate the correction value of the zenith-angle observations according to the characteristics of the zenith-angle observations error. Then statistical analysis the actual accuracy of CPâ…¢trigonometric leveling before and after the correction of the zenith-angle observations respectively used the unilateral leveling method and the zenith distance correction method.Statistical results show that about 99.29% and 98.57% of the difference values between the leveling elevation and the trigonometric elevation of the CPâ…¢ control point are from-3 mm to 3 mm after the correction of the zenith-angle observations respectively used the unilateral leveling method and the zenith distance correction method, which increased 3.58% and 3.58% respectively compared with the situation before correction of the zenith-angle observations. The mean square error of CPIII triangle elevation all fall into the range from-2 mm to 2 mm after the correction of the zenith-angle observations. The height difference of longitudinal and lateral adjacent point after the correction of the zenith-angle observations basic meets the requirement of the tolerance. two methods can improve the precision of CPIII trigonometric leveling. But the unilateral leveling method is higher than the zenith distance correction method.The above two correction methods can improve the efficiency of CPIII control network, it has good practical value. The zenith distance correction method is more conducive to the application in actual work of the CPIII trigonometric leveling technology, because it avoid the work of leveling.The research results have a certain reference value to the data processing of CP III trigonometric leveling. |
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