后验方差法在地铁隧道平面控制网稳定性分析中的应用

摘要

在狭长的地铁隧道中,常使用自由设站法测量监测点的水平位移,但如果基准点发生变动,将无法得到监测点的准确位移,因此对控制网中基准点的稳定性分析至关重要. 在平差计算得到后验方差后,构造卡方检验判断控制网是否稳定,如果网中存在不稳定的基准点,再利用t检验法分别对各基准点的观测值残差进行判断,找出不稳定的基准点. 剔除该基准点. 重复上述步骤,直至卡方检验可以通过. 最后通过实例分析,验证了该方法的有效性,可为类似工程提供借鉴.%Free station method is always used in horizontal displacement monitoring of narrow and long Metro tunnel , however ,correct deformation data would not be obtained if the references have some alternation .Hence it is vital to have an analysis on the stability of reference points in the control network .After getting the variance of unit weight by adjust-ment calculation ,the chi-square test is made to judge whether the control net is stable or not .If there are some unstable reference points in the network ,then t test is used to obtain the observation residual of each reference point respectively to find these unstable reference points and therefore remove them .The above steps will be repeated until the chi-square test can be passed .Finally combined with some engineering examples ,the results shows that this method is quite effective and can provide guidance and reference for similar engineering .