The accurate, efficient and economical monitoring of settlements caused by tunnel boring machines, especially in regions of particular interest such as critical inner city areas, has become an important aspect of the tunnelling operation. Besides conventional terrestrial based methods to capture settlements, satellite based techniques that can accurately determine displacements remotely, are increasingly being used to augment standard terrestrial measurements. However, not much attention has been paid to analyse the accuracy of satellite based measurement data. In addition, there is also a lack of studies on how to visualise the resulting huge amount of data in the context of both the tunnel advancement and the existing building infrastructure. This paper introduces the basics of settlement monitoring using radar interferometry methods, in particular showing the results obtained by processing radar images from the TerraSAR-X satellite to monitor a downtown construction site in Düsseldorf, Germany, where a new underground line (“Wehrhahn-Linie”) is being built. By comparing terrestrial measurements with remote satellite based settlement data in temporal and spatial corridors, the accuracy of the radar interferometry method is shown. Moreover, a 4D visualisation concept is presented that correlates satellite and terrestrial based settlement data correlated with above-ground buildings and boring machine performance parameters within a Virtual Reality (VR) environment. By comparing up to 23,000 pairs of satellite and terrestrial based settlement data points of a real tunnelling project an accuracy of about ±1.5 mm in the measurement of deformation using the method of radar interferometry in urban areas can be stated. In addition, providing a visual analysis of data sources within a VR environment, the accuracy of terrestrial and satellite-based measurements can be visualised in different time steps. Sources of error that affect the degree of accuracy, such as atmospheric conditions, systematic errors in the evaluation of radar images and local events in the spatial corridor, can be quantified. In addition, the 4D visualisation can help reveal direct interdependencies between settlement data and boring machine performance data. The Persistent Scatterer Interferometry (PSI) based on high resolution radar images of the TerraSAR-X satellite, in combination with conventional ground-based terrestrial measurements, provides a new settlement monitoring approach in tunnelling. For example, due to minimized surveying works and disruptions of construction activities on site and due to the large settlement area coming with a high magnitude of settlement data points, this combined monitoring approach is very practical and economical. Moreover, by visualizing the settlement data properly, the risk of damage of surface structures can be analysed and understood more precisely, which increases the safety of underground works.

中文翻译：

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基于雷达干涉法的隧道沉降监测：可视化和准确性分析

由隧道掘进机引起的沉降的准确，高效和经济的监控，尤其是在特别重要的地区，例如重要的市区内部，已成为隧道运营的重要方面。除了传统的基于地面的方法来捕获定居点以外，可以精确地远程确定位移的基于卫星的技术正越来越多地用于增强标准的地面测量。但是，分析基于卫星的测量数据的准确性并没有引起太多关注。另外，还缺乏关于如何在隧道前进和现有建筑物基础设施的背景下可视化所产生的大量数据的研究。本文介绍了使用雷达干涉测量法进行沉降监测的基础，尤其显示了通过处理TerraSAR-X卫星的雷达图像以监视德国杜塞尔多夫市中心的建筑工地而获得的结果，该工地正在建造新的地下线路（“ Wehrhahn-Linie”）。通过将地面测量结果与时空空间走廊中基于远程卫星的沉降数据进行比较，显示了雷达干涉法的准确性。此外，提出了一种4D可视化概念，该概念将基于卫星和地面的沉降数据与虚拟现实（VR）环境中的地上建筑物和钻孔机性能参数相关联。通过比较真实隧道工程的多达23,000对基于卫星和地面的沉降数据点，其精度约为±1。可以说在城市地区使用雷达干涉法测得的变形量为5 mm。此外，通过在VR环境中提供数据源的可视化分析，可以在不同的时间步长显示地面和基于卫星的测量的准确性。可以量化影响精度的误差源，例如大气条件，雷达图像评估中的系统误差以及空间走廊中的局部事件。此外，4D可视化可以帮助揭示沉降数据和镗床性能数据之间的直接相互依赖性。基于TerraSAR-X卫星的高分辨率雷达图像的持久散射体干涉测量（PSI），结合常规的地面地面测量，提供了一种新的隧道沉降监测方法。例如，由于最少的勘测工作和现场施工活动的中断，以及由于大的定居区以及大量的定居数据点，这种联合监测方法非常实用且经济。此外，通过适当地可视化沉降数据，可以更准确地分析和理解地表结构损坏的风险，从而增加了地下工程的安全性。