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Assessing ground interaction effects and potential damage on existing tunnels before and after new excavation works

评估新开挖工程前后对现有隧道的地面相互作用影响和潜在损害

基本信息

批准号：
EP/G063486/1
负责人：
James Standing
金额：
$ 141.63万
依托单位：
Imperial College London
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2010
资助国家：
英国
起止时间：
2010 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=EP%2FG063486%2F1
关键词：
Assessing ground interaction effects potential

项目摘要

Tunnels and underground railway systems are a popular solution to the increasing need to provide fast efficient transport systems in urban environments. Because in many cases the ground contains dense networks of existing tunnels for transportation and services and also deep foundations, new tunnels have to be constructed deeper to pass beneath these obstacles. New tunnel construction results in stress changes and consequent deformations in the ground and these are transmitted to and affect other existing structures. Services and particularly operational metro tunnels are very sensitive to such movements. Railways operate within narrow 'kinematic envelopes' and if a tunnel deforms so as to restrict this envelope the running of trains is severely restricted, requiring reduced speed limits or shutdown of the network and, in the extreme case, their stability might be compromised. At any of these levels, efficient running of the train network is severely hindered. If it is necessary to halt operation of a train line, even for a short period, there are astronomical daily costs from loss of ticket revenue and from loss of time to the commuting workforce. The societal impact is also enormous with inconvenience to thousands of people, frustration and unrest.Many existing tunnel networks were constructed over a century ago when traditionally linings were made mostly from grey cast iron segments. Little is known about the detailed response of segmental tunnel linings made from this material, e.g. how much deformation they can sustain and when and how they will fail. Grey cast iron is a very brittle material and its response depends on a number of factors such as the force in the bolts, nature of the gaskets/grommets used, and whether the 'pan' is infilled with concrete.Royal Assent for Crossrail, a new transport link across London, was granted this year. Construction is due to start in 2010. The tunnels for Crossrail are larger and deeper than most existing tunnels and they will pass beneath more than forty such tunnels. Many of these are aged and constructed from cast iron segments and transport thousands of commuters hourly.This research project sets out to gain a full understanding of the limits of deformation of existing cast iron tunnels when deformed by underground excavation such as tunnelling. Because of the nature of these linings (connections etc) it is necessary to consider their response at an appropriate scale. A three-path approach is to be adopted with laboratory testing of large-scale rings formed from cast iron segments, field monitoring of existing tunnels during Crossrail tunnel construction and numerical analysis of both laboratory and field conditions. The laboratory study will enable limits of deformation to be established, e.g. yield and failure, under different conditions such as bolt forces, gaskets types. The rings will be instrumented to monitor changes in stresses, bolt force etc as the ring is deformed to simulate typical shapes observed and predicted in situ. This is relevant to understanding conditions both before and after new tunnel construction. Numerical analysis will be used to model the laboratory set-up and refined prior to making predictions of a field situation at Hyde Park where the Crossrail tunnels will pass beneath the Central line tunnels. Comprehensive instrumentation will be installed in the ground and existing tunnels at this location to monitor in detail and understand their response during new tunnelling. The numerical analysis can then be further refined to achieve more accurate predictions for future projects.Bringing together these three research components will allow guidelines to be drawn up on expected and allowable tunnel lining deformations and the effectiveness of mitigation measures for future projects involving tunnelling beneath existing tunnels, such that safe and efficient operation of underground railway networks is not compromised.

隧道和地下铁路系统是一种流行的解决方案，以满足在城市环境中提供快速有效的运输系统的日益增长的需求。由于在许多情况下，地面包含密集的现有隧道网络，用于运输和服务以及深基础，因此新隧道必须建造得更深，才能在这些障碍物下方通过。新隧道施工导致应力变化和随之而来的地面变形，这些变形会传递到并影响其他现有结构。服务，特别是运营中的地铁隧道对这种移动非常敏感。铁路在狭窄的“运动包络线”内运行，如果隧道变形以限制该包络线，则列车的运行将受到严重限制，需要降低速度限制或关闭网络，并且在极端情况下，其稳定性可能会受到损害。在任何这些层面上，列车网络的有效运行都受到严重阻碍。如果有必要停止一条铁路线的运营，即使是很短的一段时间，每天的票价收入损失和通勤劳动力的时间损失都是天文数字。社会影响也是巨大的，给成千上万的人带来不便，沮丧和不安。许多现有的隧道网络是在世纪前建造的，当时传统的衬砌主要由灰铸铁段制成。关于由这种材料制成的节段式隧道衬砌的详细响应知之甚少，例如它们可以承受多大的变形以及何时以及如何失效。灰铸铁是一种非常脆的材料，其响应取决于许多因素，如螺栓中的力，所用垫圈/垫圈的性质，以及“锅”是否填充有混凝土。横跨伦敦的新交通线路Crossrail今年获得了皇家批准。工程将于2010年开工。横贯铁路的隧道比大多数现有隧道更大更深，它们将在40多个这样的隧道下面通过。这些隧道中的许多都是由铸铁段建造的，每小时运送数千名乘客。本研究项目旨在充分了解现有铸铁隧道在地下开挖（如隧道开挖）变形时的变形极限。由于这些衬里（连接等）的性质，有必要考虑它们在适当规模下的响应。将采用一种三路径方法，对由铸铁段形成的大型环进行实验室测试，在Crossrail隧道施工期间对现有隧道进行现场监测，并对实验室和现场条件进行数值分析。实验室研究将能够在不同条件下（如螺栓力、垫圈类型）确定变形极限，例如屈服和失效。将对环进行仪表化，以监测环变形时应力、螺栓力等的变化，以模拟现场观察和预测的典型形状。这与了解新隧道施工前后的情况有关。数值分析将用于模拟实验室设置，并在对海德公园的现场情况进行预测之前进行改进，其中Crossrail隧道将从中央线隧道下方通过。综合仪器将安装在地面和现有的隧道在这个位置，以详细监测和了解他们的反应，在新的隧道。将这三个研究部分结合在一起，就隧道衬砌的预期和允许变形以及缓解措施的有效性制定指导方针，以便在现有隧道下进行隧道施工的未来项目中，不影响地下铁路网络的安全和有效运营。