民乐盆地短水准测量精度分析与改进措施

根据误差理论及在民乐盆地等测量场地的观测试验结果，对影响短水准测量精度的各种因素进行了分析研究。结果表明，短水准测量精度主要受４种干扰因素影响：（１）温度变化引起水准标尺尺长误差；（２）仪器单面受热的影响；（３）尺桩升降的影响；（４）地面折光的影响。特别是第４种因素的影响尤为显著。针对上述４种干扰，本文提出了一些相应的改进措施。作者将这些措施应用到实际观测中，收到了较明显的效果。

THE ANALYSIS OF SHORT-RANGE LEVELING ACCURACY IN THE MINLE BASIN AND ADVANCED MEASURES

Based on the theory of error,analysis on several factors which affected the short-range leveling accuracy in the Mime Basin and in-site test were done. The result shows that the accuracy of short-range leveling was mainly affected by four interference factors as follow: (1)error of leveling rod length which was caused by change of temperature; (2)the instrument warmed only on one side; (3)sinking of rod stake F (4)photo-refraction error on ground. It is emphasized that the fourth factor was more disadvantageous than the others. Therefore,some advanced measures against the disadvantageous factors were adopted and abvious effect was obtained, the observed precision was raised from ±0.40 mm/km to ±0.26 mm/km.