在伦敦的天空中精确定位

作者：Renata BarradasGutiérrez

City landmarks are not built overnight. In between planning, design and construction, there are other crucial activities - just like monitoring and positioning - happening at the same time.

22 Bishopsgate, a287-metre-tall skyscraper, rose through the air in London’s financial district in the United Kingdom. Planned with the ambition to be the capital’s first ‘vertical village’, 22 Bishopsgate isLondon’s second tallest building。

构建让这个具有里程碑意义的ris的核心e, Careys Civil Engineering, a well-known construction company with a proven track record of delivering projects that enhance the built and natural environments of communities and infrastructure in the United Kingdom and Ireland, delivered the concrete works using a self-erecting jump form system – the first of its kind to be used in the UK.

Building62层, with a floor space of more than120,000 square metresrequired Careys Civil Engineering to pour58,000立方米的混凝土并使用7,500 tonnes of reinforcement。在如此庞大的复杂而充满挑战的项目上蓬勃发展需要创新的方法论

- 就像为Leica Geosystems为Careys土木工程开发的建筑定位系统一样。Careys土木工程设计为跳跃高层建筑的量身定制解决方案提供了参考坐标，以监视和执行施工期间的测量任务。

Doing it the Careys’ and Geosystems’ way

22个主教的两个核心墙是由Careys土木工程制造的，该墙壁工程师使用跳跃形式系统进行了几种混凝土倒入。跳板系统是工作平台或钻机，用于修复模板，钢固定和混凝土。该系统适用于高层结构中多层垂直混凝土元件的构建。

After each jump, or elevation of the rig to build a new level, the Careys Civil Engineering surveying team needed reliable coordinates to proceed setting out the structure and verifying the correct positioning of the core. The main task of the automated positioning system Leica Geosystems created is to obtain precise and reliable coordinates during the entire construction process that are not influenced by the movement of the building.

This tailor-made GNSS-based monitoring solution consisted of:

• 七Leica GM30 GNSS receivers for monitoring
• 七Leica AR10 GNSS天线
• Leica GeoMoS Monitor
• Leica GNSS Spider software
• HXGN SmartNetreference station network
• Tiltmeters

With the above-mentioned hardware and software combination, Leica Geosystems developed a procedure, using GNSS observations combined with tiltmeters (precision inclination sensors), to obtain reliable coordinated points at the top of the formwork of the ascending skyscraper. Those coordinated points, or Active Control Points (ACP), are sighted by Leica Geosystems robotic total stations to setup its coordinates and orientation.

“Above a certain height, in central London, ground control points were not usable or visible anymore; the GNSS system was able to provide reliable coordinates with no need for ground controls,” said Damien Watson, senior engineer at Careys Civil Engineering, Plant and Fleet department.

To set up the automated positioning system, GNSS stations were coupled with Leica Geosystems 360-degrees prisms, so the positioning information provided by the GNSS sensors was available to be used as reference points for the surveyors performing the survey of the core wall with Leica Geosystems robotic total stations.

High-precision tiltmeters, fixed at the same locations of the GNSS antennae, were coupled to the GNSS station to track the verticality of the GNSS antennae in order to provide, at each computation, the most accurate coordinates. SmartNet network was used to provide reference coordinates to the GNSS stations on the rigs and compute the baselines.

Ensuring a smooth data flow

To obtain the ACP, data was collected, stored and post processed with Spider Software at a dedicated PC to deliver the most accurate coordinates for the team. Spider is the control centre software where positioning information was computed. The data from the GNSS stations on the rig and data from the SmartNet Reference Network was combined to provide every six hours the most accurate set of coordinates for each point for Careys Civil Engineering team. Spider coordinates were automatically transferred to GeoMoS Monitor where they were transformed into local coordinates and adjusted based on tiltmeters data.

“Leica GeoSystems解决方案允许在需要时进行完全自动化的工作流程和结果计算，并在需要时快速交付坐标，优化调查团队的成本和运行时间与不同的方法相比，” said Watson.

The team was, furthermore, able to check the number of satellites tracked and data quality of each single point in the Spider interface in real time. All these quality checks provided in real time the high level of positioning measurement accuracy that Careys Civil Engineering needed to build this landmark.

每个跳跃和处理期之后，机器人总站都可以使用新的有效控制点坐标来测量结构中的任何标记或对象。然后，现场的Careys土木工程团队继续在所有控制点都可以看到机器人总站。

The robotic total station determined its own position and orientation observing the control points and checking the results with the coordinates given by GeoMoS. In this way, the robotic total station observed all relevant points to be checked during the construction.

建立在上升

Accurate and reliable positioning on the status of structures displayed as actionable data is crucial to make fast and informed decisions and react to potential problems. The GNSS-based monitoring system has proven so successful that Careys Civil Engineering will be using it in future projects, such as the construction of a new tower in Manchester.

“勒ica Geosystems solution automatically delivered reference coordinates to the surveying team when needed, and the accuracy got better and better while the structure was growing building confidence after every jump,”沃森总结。