结构变形监测的单频GPS动态三差法

Dynamic Tripledifference Method for Single Frequency GPS Deformation Monitoring

摘要:

分析了单历元和似单差两种GPS监测方法的不足,提出了适于工程结构快速、大变形监测的单频GPS动态三差法.该方法利用两个连续跟踪历元形成的三差相位值建模,直接提取动态变形,所建模型无整周模糊度，伪距单点定位和单频载波相对定位即可分别满足其对基准点和基线向量的初值精度要求，适用于动态变形量大于半个波长的量测实践.将单频动态三差法应用于南京长江三桥结构振动监测数据处理,计算结果表明,所提方法与双频单历元法解算的高程变形在5 mm均方误差意义下一致,且基于该方法得到的动态变形序列准确地提取了三桥主梁一阶竖弯处的固有频率0.25 Hz及其响应信号,验证了模型与方法的正确性.

Abstract:

The shortcomings of both the singleepoch method and the similar singledifference approach for GPS deformation monitoring are analyzed,and then the dynamic tripledifference (DTD) method,which uses single frequency carrier phase observations of two epochs tracking continuously by tripledifference,is proposed for dynamic deformation estimation of the structural monitoring with single frequency GPS.The DTD method is characterized by its nonambiguity resolution,lower accuracy requirements for initial values of reference station and baseline vectors,and unnecessary upperbound restriction to the actual deformation.Thus,the DTD method is expected to be superior to the existing methods for its dynamic features of realtime structural monitoring.Finally,structural vibration monitoring method is applied to the third bridge of Nanjing Yangtze River.Deformation by DTD method is consistent with that by singleepoch method in about 5 mm root mean square error.Moreover,with the empirical mode decomposition (EMD) and Fourier spectrum analysis,the spectrum of the bridge dynamic deformation derived from the proposed method exhibits a dominant peak at 0.25 Hz,which coincides with that obtained from finite element computation.