Norway's rennfast link: The world's longest and deepest subsea road tunnel

The western coast of Norway consists of many long fjords. This article describes how two of these fjords are crossed by two subsea road tunnels, 5,860 m and 4,405 m long, respectively. The longer tunnel, the Byfjord Tunnel, is the world's longest and deepest subsea road tunnel, at 223 m below sea level. The paper describes the preliminary investigations and geological conditions for the tunnels, each of which has three lanes, and a total width of 11 m.     

Steel-shell immersed tunnels- Forty years of experience

The author traces his forty years of experience in immersed tunnel design and construction. The paper provides a brief history of of immersed tunnel technology from its beginnings in the early nineteenth century, and describes some of the major developments that have improved immersed tunnel design and construction methods. In a number of cases, immersed tunnelling techniques are related to the submerged floating tunnel (SFT) concept. The paper also relates some case histories of unforeseen problems that have occurred in the construction of some immersed tunnels.     

南京地铁1#线隧道典型区段施工技术

结合南京地铁1^#线施工实践，介绍了该地铁沿线浅覆土条件下的水下盾构施工、大跨度软流塑土层下的管棚施工及浅覆土建筑物下岩层控制爆破等难点区段的施工技术，希望对同类地层条件下的隧道施工提供借鉴。     

Feasibility Study of Submerged Floating Tunnels Moored by an Inclined Tendon System

Concepts of submerged floating tunnels (SFTs) for land connection have been continuously suggested and developed by several researchers and institutes. To maintain their predefined positions under various dynamic environmental loading conditions, the submerged floating tunnels should be effectively moored by reasonable mooring systems. With rational mooring systems, the design of SFTs should be confirmed to satisfy the structural safety, fatigue, and operability design criteria related to tunnel motion, internal forces, structural stresses, and the fatigue life of the main structural members. This paper presents a feasibility study of a submerged floating tunnel moored by an inclined tendon system. The basic structural concept was developed based on the concept of conventional cable-stayed bridges to minimize the seabed excavation, penetration, and anchoring work by applying tower-inclined tendon systems instead of conventional tendons with individual seabed anchors. To evaluate the structural performance of the new type of SFT, a hydrodynamic analysis was performed in the time domain using the commercial nonlinear finite element code ABAQUS–AQUA. For the main dynamic environmental loading condition, an irregular wave load was examined. A JONSWAP wave spectrum was used to generate a time-series wave-induced hydrodynamic load considering the specific significant wave height and peak period for predetermined wave conditions. By performing a time-domain hydrodynamic analysis on the submerged floating structure under irregular waves, the motional characteristics, structural stresses, and fatigue damage of the floating tunnel and mooring members were analyzed to evaluate the structural safety and fatigue performance. According to the analytical study, the suggested conceptual model for SFTs shows very good hydrodynamic structural performance. It can be concluded that the concept can be considered as a reasonable structural type of SFT.     

上海第④层淤泥质粉质粘土的热传导特性

地层土体的热传导特性是开展地铁隧道周围土体温度场分析的关键参数。本文采用基于热探针法的KD2热传导仪,对上海地区地铁隧道经常穿越的第④层淤泥质粉质粘土的热传导特性进行了试验测试,分析了热导率与孔隙比的相关性,并应用若干现有经验公式对上述热传导试验数据进行了拟合,以检验各公式的适用性。结果表明:淤泥质粉质粘土的孔隙比越大,其热导率越小,上海第④层淤泥质粉质粘土的热导率变化范围在0.98~1.25 Wm^-1K^-1之间,使用Woodside公式能较好地拟合淤泥质粉质粘土的导热系数。     

Design of bored tunnel linings for Singapore MRT North East Line C706

The northern section of the bored tunnels of Contract C706 of the Singapore MRT North East Line is located in varying soil conditions ranging from cemented Old Alluvium to very soft marine clay. The bored tunnels will run along Race Course Road, underneath a residential area underpassing several religious temples. The tubes will be constructed by earth pressure balanced shield machines. The paper is presenting the key approaches adopted for the design of the tunnel lining, the assessment of ground movements under the particular circumstances as well as the basic design considerations for the intersection of MRT tunnels with the future tunnels of the Singapore Underground Road System (SURS). In this context, the effect of water pressures in terms of sectional lining forces was studied in detail. A design chart has been developed to determine the sectional forces due to the water pressure load and in relation to the subgrade reaction modulus. An approach to consider the influence of the second tunnel has been developed and its presented in this paper.     

Analytical solution for tunnelling-induced ground movement in clays

Elastic solutions are presented to predict the tunnelling-induced undrained ground movements for shallow and deep circular tunnels in soft ground, by imposing the oval-shaped ground deformation pattern as the boundary condition of the displacement around the tunnel opening. The gap parameter is used to describe the displacement at the opening. The difference between uniform radial and oval-shaped ground deformation patterns on ground deformations is investigated and different definitions for ground loss are discussed. The applicability of the proposed analytical solutions is checked with five case studies. Generally good agreement of the predicted ground deformations can be seen with field observations for tunnels in uniform clay.     

复杂环境条件下砂质粘土隧洞施工监控量测研究

在隧洞施工中进行安全监控量测是必不可少的。通过对重庆主城排水工程CQWW2.01标段57#～61#隧洞施工监控量测结果的分析,介绍了复杂环境条件下围岩为砂质粘土隧洞施工监控量测的基本方法,总结出该类隧洞及地面变形的基本规律,对今后类似工程的施工监测提供重要的参考价值。     

近距离交叠隧道施工影响的数值模拟

由于地质条件的限制及地下空间的综合开发利用,在工程中有时不可避免地产生近距离交叠隧道.对于这种型式的隧道,新建隧道是在既有隧道完成之后修建的,新建隧道的施工势必影响既有隧道结构的受力状态,引起既有隧道变形.本文应用ANSYS有限元程序采用三维弹塑性数值计算方法对某新建铁路隧道下穿既有高速公路隧道的施工过程进行了模拟,揭...     

Support pressure for circular tunnels in two layered undrained clay

To estimate the required support pressure for stability of circular tunnels in two layered clay under undrained condition,numerical solutions are developed by performing finite element lower bound limit analysis in conjunction with second-order cone programming.The support system is assumed to offer uniform internal compressive pressure on its periphery.From the literature,it is known that the stability of tunnels depends on the overburden pressure acting over it,which is a function of undrained cohesion and unit weight of soil,and cover of soil.When a tunnel is constructed in layered undrained clay,the stability depends on the undrained shear strength,unit weight,and thickness of one layer relative to the other layer.In the present study,the solutions are presented in a form of dimensionless charts which can be used for design of tunnel support systems for different combinations of ratios of unit weight and undrained shear strength of upper layer to those of lower layer,thickness of both layers,and total soil cover depth.     

Model-based airflow controller design for fire ventilation in road tunnels

This paper describes a new approach to design the proportional-integral-derivative (PID) controller of the longitudinal airflow velocity in road tunnels for fire situations. Our work shows clearly that the use of a proper model provides valid data for model-based tuning of tunnel controllers, which is demonstrated by real tunnel tests. The design uses the simplified mathematical model of airflow dynamics based on Bernoulli and continuity equations, which describe the airflow dynamics in one dimension. Optimizing controller parameters on site is very time consuming and this problem increases in the case of complex tunnels with several entrance and exit ramps, which typically have occurrences of traffic congestion. Our approach is based on the design of the controller through simulations, which use the mathematical model of airflow velocity in the tunnel. This approach spares a lot of work and time with the controller tuning within tunnel tests. Moreover, it can discover potential problems, which can occur during real instances of fire in the tunnel. The additional advantage of this approach is a possibility to simulate a scenario of errors and failures of some devices, which are important for reliable control of longitudinal airflow velocity. Although this approach is focused primarily on complex road tunnels, due to their complexity and significant time savings with the controller tuning, it can be also used for simpler tunnels with no ramps (usually highway tunnels) where the design of the airflow controller is not as complex compared to the case of road tunnels. This paper also includes a case study of the airflow controller design for the Blanka tunnel complex in Prague, Czech Republic, which is the largest city tunnel in Central Europe.     

高速公路浅埋大跨度双跨连拱隧道爆破振动影响研究

沪蓉高速公路宜昌-恩施段修建在崇山峻岭之中,其桥隧长占路线总长的50％,为减少工程的投资,在部分地段将采用浅埋双跨连拱隧道的方案来实现桥隧的合理过渡。在小间距(5.5-25m)隧道过渡段,隧道爆破将对相邻隧道的稳定性造成较大影响。为确定合理的爆破装药量以确保相邻洞室围岩在爆破振动时的稳定性,应用有限差分法FLAC3D程序对钻爆法施工时爆破孔进行起爆加载,动态模拟了隧道在不同围岩特性条件下装药量大小对相邻洞室围岩关键点的影响程度,得到了爆破时围岩的振动速度历时曲线和围岩的破损情况,并提出了确保工程稳定的合理装药量,研究成果为工程的设计与施工提供了科学依据。     

汶川地震公路隧道洞口结构震害分析及震害机理研究

通过对汶川地震公路隧道震害调查资料的统计分析,对隧道洞口结构进行了震害分析,结果表明：洞外结构受次生灾害影响较大,地震惯性力影响明显;硬岩洞口段隧道结构基本无破坏,软岩洞口段隧道结构震害较严重。通过三维有限差分数值模拟计算和现场典型震害分析,研究了公路隧道洞口结构的震害机理。探明了洞外结构震害机理,即洞外结构受次生灾害影响较大,震害的主要原因是地震惯性力,洞门墙结构和基础设计不合理以及隧道洞口所处位置也是影响洞外结构震害的重要因素。探明了洞口段隧道结构震害机理,即正穿坡面洞口段隧道结构存在软硬围岩交界面时,其附近软岩内隧道结构受较大强制位移作用;正穿坡面洞口段隧道结构覆盖层为软岩时,震害的主要因素是地震惯性力。研究成果对公路隧道洞口结构的抗减震技术有着重要的意义。     

Control of surface settlements with umbrella arch method in second stage excavations of Istanbul Metro

In metro tunnel excavations, it is important to control surface settlements observed before and after excavation, causing damages to the surface structures. Otherwise, metro tunnel cannot perform the task expected and the advantages of metro tunnel are lost. For this purpose, second stage excavation of Istanbul Metro between Unkapani and Yenikapi was studied. Geology in this section is composed of clay, claystone, sand and marl. New Austrian tunnelling method (NATM) was used in tunnels having cross-section of 36 m². In this study surface settlements are compared for NATM and umbrella arch method (UAM) in sensitive regions. As a result of this study, it was found out that surface deformations especially in clay bearing formations could be controlled efficiently by using the UAM.     

盾构穿越引起的既有盾构隧道纵向变形研究

研究既有隧道在新建隧道穿越时产生的响应,提出一种能准确预测既有隧道位移的计算方法。采用目前国内较为先进的转动错台模型,在考虑施工因素的附加荷载作用下,运用最小势能原理对既有盾构隧道在新建隧道穿越时的结构变形进行了分析预测。并分别选取了3个工程实例对新建隧道在不同穿越工况下本文方法的预测准确性进行了验证。研究结果表明:本文方法计算值与实测值较为吻合,能计算出既有隧道的竖向位移、环间的错台量、转角和剪切力,进而判断既有隧道结构的安全状态;既有隧道发生沉降时管片以错台变形为主,转动变形占比较小(约30%)。     

Water crossings — the options

Water in the shape of rivers, lakes, fjords, oceans and so on, sometimes seems to provide a barrier to improving the environment and preventing further development. Hitherto unconsidered options may be available to cross over or under a water barrier. Without full knowledge of the available possibilities, planners and decision-makers are not able to make the best-informed choices. This paper initially examines the relative attributes of bridges, ferries, submerged floating tunnels, immersed tunnels, soft ground tunnels and rock tunnels. Reasons for selection or rejection of each option are discussed. The paper goes on to introduce immersed and floating tunnels in more detail. Specific examples are given to convey the concepts.     

双平行圆形隧道稳定的塑性极限分析上限解

从塑性极限分析上限法的基本原理出发，通过分析单圆形隧道4种类型垮落机制所获得的稳定率上限解，构建黏土层中双平行圆形隧道的垮落机制，阐述双平行圆形隧道稳定与垮落间的临界稳定分析过程，导出浅土层中双平行圆形隧道稳定率的上限方程。该方程根据隧道间不同距离，综合两隧道重叠（单隧道）、两隧道相接触、相互影响的双隧道以及互不影响的两单隧道的稳定特征。通过该方程进一步讨论土重对双隧道稳定率上限解的影响。最后，由离心模型试验结果证实其上限解的正确性。     

State of the road tunnel safety technology in Japan

As more and more tunnels have been constructed to develop new road network, through mountainous ranges or to avoid environmental problems in urban areas, safety in road tunnels has been becoming a major issue. Establishment of tunnel safety measures is the most important task for all those who are engaged in road tunnel design, construction, operation or safety. Based on the past experiences of serious accidents involving fires, efforts to improve safety in road tunnels have been made by establishing technical standards with technological progress and improving emergency facilities in Japan. This paper describes the state of the road tunnel safety technology in Japan.     

拆复建桥桩对软土地层盾构隧道结构影响研究

以大直径桥桩紧邻既有地铁盾构隧道施工为研究背景,基于隧道病害调查和长期变形监测数据,分析典型河漫滩软土地区钻孔桩打、拔近接施工对盾构隧道衬砌环结构影响,并对钢护筒超前加固效果进行量化评估。结果表明:近距离桥桩拆复建工程在原隧道结构较大变形的基础上,进一步对结构病害产生不良影响,使得结构安全性储备降低,需要进行及时必要的修复性处理;淤泥质粉质黏土较其他地层内隧道受施工影响变形量更为显著;采取钢护筒措施可减少隧道62.5%位移变形量、42.9%横断面收敛变形量。     

Effects of above-crossing tunnelling on the existing shield tunnels

Tunnelling in the dense urban areas frequently results in over-crossing or bypassing the existing tunnels. It is obvious that the over-crossing tunnelling will adversely affect and even damage the existing tunnels if the induced deformation exceeds the capacity of tunnel structures. Increasing concerns have been raised about the interactions between the over-crossing tunnelling and underlying tunnels. In order to obtain a better mechanical understanding of the effects of the over-crossing tunnelling on the existing tunnels and provide a quick but low cost assessment alternative method for evaluating the behavior of underlying tunnels prior to construction, a simplified analytical method is proposed in this study. In this simplified method, the tunnel is simply considered as a continuous Euler-Bernoulli beam with a certain equivalent bending stiffness. The unloading stress at the tunnel location caused by the over-crossing tunnelling is computed through Mindlin’s solution, ignoring the presence of the existing tunnel. Then, the tunnel-soil interaction due to the relief stress is analyzed based on the commonly-accepted Winkler foundation model. The applicability of the presented method is validated by three well-documented case histories. Results of these case studies show a reasonable agreement between the predictions and observations. Finally, a parametric analysis is also preformed to investigate the influences of the different factors on the behavior of the existing tunnels, including clearance distance, advancing distance and multiple tunnels construction.