在国王十字架重建下

Authors: Lidija Špiranec & Steven Thurgood

King’s Cross is one of the most significant reconstruction projects in London, UK. The area around King’s Cross Station had 67 acres of unused land, which was designated for development in 2008. The master plan included 50 buildings, 1,900 new homes, 20 new streets, 26 new public parks and squares and 26 acres of open space.

Renewal work for this major rail hub began in 2010. One of the key constraints of the project was the presence of four railway tunnels beneath the site, which were part of the main connections with King’s Cross Station. These connections are utilised by hundreds of thousands of commuters every day.

为了进行开发项目，有必要在这些隧道的顶部建造邻近和越过。资产所有者的Network Rail结合使用，只要对隧道和轨道的任何移动进行分析，并安装了实时监控方案，就可以同意这可能发生。需要监视计划以确认预测的运动并衡量任何超越的运动，因此可以在发生任何损害基础设施之前停止工作，从而最大程度地减少对旅行者和火车的风险。

Due to the size of the project, its value and impact, the monitoring system requirements were rigorous:

Robust- to last the contract duration of 12 years
Scalable- to accommodate expansion
Accurate / Precise- 自信地衡量和报告
可重复- to obtain consistent observation
自动化- 在没有载人访问的环境中运行
连续的- 24/7操作
Accessible- 对所有利益相关者

Pell Frischmann英国领先的咨询工程companies with almost 100 years of experience, accepted this monitoring challenge. Having used various Leica Geosystems’ instruments and equipment for over 30 years, the company knew thatLeica Geosystems’ monitoring solutions由于可靠性，技术卓越，备份和支持，是正确的选择。因此，公司与SCCS调查设备有限公司，六边形的一部分bob体育报道, the UK leading distributor of Leica Geosystems Surveying Equipment, to deliver the required monitoring system.

“Leica Geosystems’ long history of developing new products, whilst fully maintaining backwards compatibility, ensured the system could be expanded with the latest equipment over the extended duration of the project. At the same time Leica Geosystems’ maintenance and support network meant that spare parts and servicing would be available for all purchased equipment, whatever its age, over the entire project life-cycle,” said Gary Weekes, director asset management at Pell Frischmann. “The support of SCCS in helping to specify suitable equipment and assist with setting up the system was also a key driver in selecting Leica Geosystems equipment for the project.”

There were two independent monitoring systems installed at King’s Cross Station – the primary one was geodetic monitoring with automatic total stations (ATS) and the backup one was geotechnical monitoring, providing redundancy in measurements, delivering additional information and increasing certainty and reliability of results.

Tailored solution for London’s tunnels

该项目使用的设备包括以下传感器：

The Leica TM30/50 monitoring total stations provided the ability to narrow the measuring laser beam detector sensitivity, eliminating the risk of interference from adjacent targets in these long linear sites, which is a unique ability of Leica Geosystems’ instrumentation. This enabled the system to be configured with fewer total stations while still maintaining the target frequency required by Network Rail. The monitoring instrumentation automatically measures:

• 隧道三维位移by measuring five prism arrays attached to the tunnel lining at 10m cross sections

• 轨geometry for cant, twist, gauge and alignment by measuring prism pairs attached to each rail of the track

Outside of the tunnels, a permanent network of stable control points was measured to eliminate the movements of the total stations.

无线倾斜节点安装在冠棱镜附近的隧道衬里上，并以3m的间隔轨道床/卧铺，以镜像铁路棱镜。无线倾斜和距离节点位于每个10米横截面的隧道衬里上，以测量隧道的收敛和卵形化。

Once everything was installed, a track geometry measuring device with scanner and its dedicated software was used to measure/verify the tunnels and ensure the monitoring equipment was clear of passing trains and kinematic envelope.

Data acquisition and processing of all geodetic and geotechnical measurements were facilitated using Leica Geosystems地球仪监视器. The software allowed for assigning priorities and control of observations, whereas the frequency of observations was remotely adjustable to match dynamic events. The computed results of prism measurements were further used for computation of virtual observation points for mathematically derived values, enabling complex calculations from a variety of data sources into a single computation model. Deformation movement limits, alarms and actions were defined with bespoke variables depending on activity and instrumentation. Data visualisation and reporting were seamlessly integrated using the cloud-based service from Leica Geosystems现在的怪异！.

Due to the complex environment and long linear nature of the project with only stable areas at each end, the total station data required correction to a homogeneous model rather than each unit working independently. Thus, a fully-integrated and automated least square adjustment of the control network was computed real time during the observation cycles using Star*Net software by MicroSurvey Software Inc., part of Hexagon. The GeoMoS system was then automatically updated with live network adjustment coordinates for the entire network prior to each monitoring array observation.

“现在使用Geomos！使我们能够为该项目建立简单，清晰的仪表板。在任何时候，有多个承包商现场，他们只对监视计划的各个部分感兴趣。Geomos监视器允许为每个承包商建立特定的警报制度，并在Geomos！Now！现在开发了个人仪表板，该仪表板特定于该承包商。”，Weekes解释说。

Overcoming monitoring challenges

There were several complex challenges that the Pell Frischmann team had to overcome during the monitoring period. In the Thameslink Tunnels, trains were passing at 50 mph every five minutes, causing vibration and air movement, affecting instrument orientation and level. The access to the tunnels was limited to two four-hour shifts every three months, so a permanent solution was found by installing GeoLaser AD-12 self-levelling tribrach to enable remote users to correct the total station back to the horizontal plane without requiring access. This was fully controlled via GeoMoS Monitor.

在Gasworks隧道中，要克服的挑战有所不同 - 油性烟灰残留物。隧道中的砖砌层厚厚，从蒸汽和柴油火车在隧道中运行的几年开始。这导致在整个监控期间持续构建残留物。因此，作为主动维护计划的一部分，需要每隔几个月清洁每隔几个月的总电视机和棱镜才能保持信号强度。

Over the life of the installation, the monitoring scheme operator with continued support from SCCS found innovative solutions to increase system reliability and reduce operational costs. This also included anti-corrosive fittings and prism covers which made them resistant to constant exposure to previously unknown environmental conditions discovered in the tunnel.

“The equipment delivered accurate and repeatable results 24/7 for extended periods of time without the need for manual intervention between the standard bi-monthly maintenance visits. This was particularly important in the Gasworks tunnels, where diesel residue and water leakage caused a particularly harsh working environment, in which the instrumentation had to operate faultlessly for 12 months between servicing,” said Weekes.

设备的可靠性和准确性确保了隧道附近开发的所有工作都可以在2010年以后的十年后继续进行。这种灌输了网络铁路对系统的信心，并且无需停止或慢速火车，避免任何经济罚款延误都将产生。”

未来的防止监控数据

Once the regeneration of King’s Cross is completed, monitoring of the tunnels will continue. The importance of this dataset rests in recording the natural movement and condition of the tunnel. This could become an important asset for engineers to determine life cycle extensions of the tunnels and to plan preventative maintenance.

“The client and all stakeholders were very happy with the system and its performance. They particularly liked the real time unlimited access to the data, which enabled them to check any minor triggers and see trending without the need for any specialist knowledge or training on the system. We plan on sharing our level of satisfaction with this product within this collaborative network of companies, so it can be utilised on a wide range of projects,” concluded Weekes.

“Pell Frischmann provides innovative solutions working closely with Leica Geosystems and wider Hexagon team. They have responded promptly to any issues, including out of hours and have saved the project from the costs of any delays to trains”, added Alastair Mitchell, project director of Kings Cross Partnership.