New developments in TBM tunnelling for changing grounds

Mechanized tunnelling has seen substantial growth in the recent years in the construction industry for small to large scale infrastructure works. This development is due to a growing number of large-scale projects that were successfully realized with certainty and reliability in construction, compliance with construction schedules and thus supported the economic success of the projects. Tunnel projects are planned and implemented today in changing grounds that could not be realized without the newest technological progress and innovations in mechanized tunnelling. Today’s demand in tunnelling is to construct tunnels with high safety standards especially in urban areas with sensitive geological and hydrogeological conditions. In the context of this publication, new developments in TBM tunnelling related to changing ground conditions are highlighted. References of major infrastructure projects will be addressed that illustrate also the effect and importance of mechanized tunnelling technology used today to complete infrastructure projects on time and with high quality and technical standards.     

Status of tunnelling and underground construction activities and technologies in India

A considerable amount of tunnelling work has been going on in India for hydroelectric, irrigation, roads and railways projects. Most of these projects are located away from urban areas. The use of tunnelling for urban utilities, such as water supply, sewerage disposal and metro rail has recently begun. A few projects have been completed and some are under construction in metropolises such as Mumbai, Calcutta and Delhi. The present status of tunnelling and its future potential in India is highlighted in the paper with emphasis on tunnelling projects for hydro-power developments, as this sector presently has maximum underground construction activity in India. The tunnelling technologies for planning, design and construction have also been presented in this paper.     

圆砾泥岩复合地层泥水盾构下穿房屋沉降控制技术研究

圆砾泥岩复合地层中盾构微扰动施工控制是岩土工程实践中面临的难题。南宁地铁1号线盾构下穿友爱居民小组面临圆砾与泥岩复合地层的挑战,首先对泥水盾构泥浆性能指标进行优化,采用现场试验确定了富水圆砾地层袖阀管注浆加固浆液配合比;利用自动化监测系统对盾构下穿房屋的沉降进行实时监控,并借助及时通讯工具实现穿越施工中信息化施工;定义圆砾泥岩复合地层盾构开挖面内泥岩高度与盾构机刀盘直径的比值为复合比λ,分析掘进参数平均值随λ的变化规律。通过现场实测结果表明:袖阀管注浆能够有效的控制建筑物沉降,自动化监测能够实时反映盾构推进导致房屋变形,为施工反馈控制提供依据,泥水盾构在圆砾泥岩复合地层中会遇到开挖仓压力波动过大,刀盘扭矩、推力增大,贯入度降低等现象。当λ≤0.15上述现象基本不发生;当0.15≤λ0.6时,参数平均值波动最剧烈,对沉降控制十分不利;当λ≥0.6时,扭矩和总推力进一步增大,但开挖仓压力波动情况稍弱而贯入度会进一步降低。要以盾构开挖仓压力控制为指标而非追求推进速度,提高转速、降低泥浆黏度是减少参数波动的有效手段。     

Geotechnical aspects of rock tunnelling in China

To meet the huge demands of transportation, energy and other infrastructure projects, a large volume of rock tunnelling is being carried out across the country as China embarks on her modernization plan. This paper summaries the geotechnical issues encountered on such projects, including the various modes of rock mass instability and geological hazards. Methods of evaluating rock mass quality and ground conditions as developed in the West are now widely used on tunnelling projects in China. As well Chinese engineers and researchers have also developed geomechanical systems for rock mass classification, failure modes and support requirements. These systems have been proven to be effective in dealing with the complex geologic and tunnelling conditions in China. Also described in the paper are analytical techniques currently used in China for tunnel performance prediction, including canonical analysis, expert systems, block vector analysis and advanced numerical modelling techniques.     

A quantitative evaluation of the sustainability or unsustainability of three tunnelling projects

There is a perception that tunnelling is sustainable. This is because it occurs underground, and consequently does not significantly interfere with surface or atmospheric processes unlike other anthropogenic activities. However, the tools and assessments used in tunnelling projects to evaluate sustainability in the construction and operational phases are primarily concerned with the reduction of carbon footprint and environmental performance. This does not provide a suitable approach to determining the sustainability of a tunnelling project directly. Environmental Impact Assessment (EIA) on the other hand does have this potential. However, it requires two things: (1) a suitable quantitative-based method of EIA; and most critically and (2) a means to evaluate sustainability from the EIA results. Based upon the recent work of Namin et al. (2014) concerning a new EIA methodology for tunnelling projects, this paper applies an established mathematical model of sustainability to the results of the EIA to determine the sustainability or unsustainability of tunnelling projects. The model’s application, in the form of an algorithm, evaluates three case studies assessed by Namin et al. (2014). The results are analysed and discussed in respect to the three projects’ construction and operation phases. The broader context of the results is then discussed in respect to the use of underground space as a means to achieve sustainability.     

北京第三系粘土岩的工程特性研究

在北京市区西部工程建设中常遇到第三系粘土岩,特殊的成岩历史和成岩作用使其具有独特的工程特性。本文以第三系粘土岩的现场观测及室内试验结果为基础,研究了第三系粘土岩的地质特征、物理力学性质,并对其环境影响效应及开挖条件下强度的变化进行了分析,提出基坑施工时应采取适时快速开挖、快速封闭和围（支）护的处理方法。研究结果对工程建设具有一定参考价值。     

Rock mechanics for design of Brisbane tunnels and implications of recent thinking in relation to rock mass strength

This paper explores the potential implications of recent thinking in relation to rock mass strength for future tunnelling projects in Brisbane, Australia, particularly as they are constructed within deep horizons where the in situ stress magnitudes is larger. Rock mass failure mechanisms for the current tunnels in Brisbane are generally discontinuity controlled and the potential for stress-induced failure is relatively rare. For the road tunnels which have been constructed in Brisbane over the last 12 years, the strength of the more massive rock masses for continuum analysis has been estimated by the application of the Hoek-Brown (H-B) failure criterion using the geological strength index (GSI) to determine the H-B parameters m_b, s and a. Over the last few years, alternative approaches to estimating rock mass strength for ‘massive to moderately jointed hard rock masses’ have been proposed by others, which are built on the work completed by E. Hoek and E.T. Brown in this area over their joint careers. This paper explores one of these alternative approaches to estimating rock mass strength for one of the geological units (the Brisbane Tuff), which is often encountered in tunnelling projects in Brisbane. The potential implications of these strength forecasts for future tunnelling projects are discussed along with the additional work which will need to be undertaken to confirm the applicability of such alternative strength criteria for this rock mass.     

Immersed tube tunnelling offshore: Execution of immersed tube tunnelling projects under offshore conditions, based on studies for the euroroute fixed channel link proposal

The development of the international road and railroad network has suffered from the worldwide stagnation in economy over the past years. Nevertheless, leading economists consider new, large international infrastracture projects to be a necessity for an upturn in the economy. Among these projects are a number of connections over or under sea straits, such as Gibraltar and the English Channel. With the completion of the Seikan Tunnel, Japan has already executed such a project. The study for Euroroute's fixed Channel link proposal indicated that an immersed tube tunnel is a realistic and, often, favorable solution. Thanks to the development of immersed tube tunnelling technology, the development of the offshore industry, and work on recent large projects (such as the Dutch Eastern Scheldt Storm Surge Barrier), tunnelling techniques have improved considerably. This article provides a brief comparison between bored and immersed tunnelling solutions. The article mainly focuses on hydraulic problems, dredging and immersing the tubes. The following questions are considered: What circumstances and conditions influence the applicable methods such as surveying, dredging, immersing and related equipment? What considerations must be taken into account on immersed tube tunnelling projects?     

Developments and quality safeguards in immersed tunnel technique

Over the past decade, quality assurance has become increasingly important in immersed tube tunnelling. A guarantee of meeting quality standards has become paramount in obtaining financing for high-risk tunnelling projects. To assist in designing such works to guarantee durability and watertightness, the Dutch Ministry of Public Works has begun a project to inspect thoroughly and record information about various civil engineering projects, including immersed tunnels. A computerized program will describe problems with quality, define repair needs and link this information to repair and maintenance costs. This paper discusses ways to control the concrete-hardening process (a major concern in assuring quality in tunnels) through computer-assisted engineering programs in order to obtain a high-quality product. Advantages of computer-aided design systems are addressed, as are future needs with regard to solving problems associated with tunnel leakage.     

Interesting solutions for the construction of tunnels under waterways in Germany

The soil in the Tertiary and Quarternary formations characterize the constructions methods for underwater tunnels in the Federal Republic of Germany. The floating method and the method of lowering precast tunnel sections have been used for tunnelling below waterways for large ships. The floating sections were up to 140 m long and had a displacement of approx. 46 000 m³. A number of construction methods were available for various construction projects for tunnelling below rivers and inland water canals. Several examples are given.     

Construction of underground works in Shanghai, P.R.C.

For nearly thirty years, Shanghai has been constructing underground works designed to improve the city's infrastructure. A number of projects were undertaken using shield tunnelling method in order to determine whether this method could be used successfully in Shanghai's geology, which is characterized by silt and silty or puddly clay. These underground projects have included subway tunnels, sewage and water supply tunnels, road tunnels, and offshore discharge tunnels. This paper describes eight subsurface projects in Shanghai that have used the shield tunnelling method successfully.     

A review of the impact of the RingRing study for multifunctional motorway tunnels in the Netherlands and beyond

In the early 1990s, it became clear that tunnelling as Dutch engineers knew was about to change fundamentally. Local governments, pressure groups and individuals had become aware of the added value that underground space technology (tunnelling) could bring, giving rise to the next generation of multifunctional road and rail tunnel projects. This article reports on the outcome of a landmark study that focused on the new opportunities that multifunctional tunnels for motorways offer: RingRing. The RingRing study includes a concise state-of-the-art exploration of path-finding projects, delivers a solid methodology for dealing with the many design decisions during the conceptual phase of the multidisciplinary project, proposes a set of generic concepts that respond to the four key challenges faced by multifunctional tunnels, conducts two showcase design study projects, and provides an overall analysis of the applicability of multifunctional tunnels for integrating orbital motorways in large cities such as Amsterdam and Rotterdam. Eight years after the publication of the RingRing study, the first projects it identified are built. Others projects have not yet made it off the drawing board. This article looks back to assess what has been accomplished and draws lessons learned in order to be able to improve future projects.     

Australia's tunnelled infrastructure: Current trends and projects

Tunnelling for the Australian national infrastructure has experienced a number of cycles in the post-war years, commencing with tunnelling for hydroelectric works. At present, road tunnelling is important, and microtunnelling is an emerging field. Sydney has become the focus of a substantial volume of civil underground construction. Current major projects under design or construction throughout Australia are described.     

Wireless networking in tunnelling projects

Emerging collaborative technologies and working methods often require tremendous engineering and organisational efforts for successful implementation of information and communication technologies (ICTs). According to a research conducted in Turkish construction industry, most of the problems that occur during the construction phase are due to lack of co-operation and communication between designers and contractors and lack of prompt expert decisions during on-site engineering. Similar to any major construction project, tunnelling project’s success is highly dependent on collaborative team work where communication and information exchange take place between project members. Distributed collaborative teamwork, as the case in most of the large scale construction projects as well as tunnelling projects, empowered by state of the art information and communication technology, promises more efficient work processes, reduced travelling needs, and increased opportunities for project communication. Following the fast development of mobile computing in recent years, many sectors have adopted mobile devices and wireless technologies enabling real-time information transfer thereby improving business processes. For some years, the feasibility of implementing wireless solutions to construction sites has been researched. Potentially, mobile and wireless technologies enable construction staff to be more flexible in terms of location and time. For better use of mobile collaboration in construction projects, mobile technologies and construction sector have to be examined in some detail to implant the most suitable technology for real-time information access and improved collaboration of distributed teams in construction. However, case studies in construction are very limited in number and scope. This paper discusses and proposes an implementation scenario of wireless networking in Marmaray; a multi-site tunnelling project in Istanbul. Benefits, possible problems and cost assessments are discussed.     

Tunnelling projects in Southern Africa

Until some thirty years ago tunnelling in southern Africa for civil engineering purposes had been on a relatively small scale and of a sporadic nature. The first major tunnel to be built in the region was the 82 km long Orange-Fish Tunnel. Since 1970 more than 175 tunnels with an aggregate length of just over 400 km have been built. Much of the first phase of the Lesotho Highlands Water Project, which will have more than 100 km of tunnels, is about to be completed. The last thirty years represent the busiest period of tunnelling by civil engineers that southern Africa has ever known. The paper starts by summarising the early history of tunnelling in the region, and goes onto describe recent and current tunnelling projects. It also gives an indication of the possible demand for tunnels in the future.     

EPBMs for the North East line project

Fifteen years ago construction started on phase one of the Mass Rapid Transit tunnels in Singapore. Since that time tunnelling technology has advanced considerably. Earth Pressure Balance Machines (EPBMs) are far more commonly used than ever before on tunnelling projects in the Far East, Asia and Europe. For the first time in Singapore full-face tunnelling is being carried out in the Old Alluvium for the construction of North East Line Project (NELP). The TBMs selected for the NELP are, in the main, EPBMs. This paper compares the types of EPBMs chosen for each Contract, highlighting the particular design features of each. The paper also provides an update on the progress of the EPBM tunnelling operations currently being undertaken on the NELP.     

Analysis of the behaviour of a yield-control support system in squeezing rock

Recent innovations in yield-control support systems allow to increase the rate of advance when tunnelling in difficult conditions is associated with severely squeezing rock. Such systems which imply the insertion in the lining of highly deformable concrete elements are being adopted successfully in tunnelling projects using conventional excavation methods. The Saint Martin access adit excavated in a Carboniferous Formation along the Base Tunnel of the Lyon-Turin rail line is presented as a case study. Numerical analyses are discussed to compare the results of computed and measured performance of a typical monitored section and to find out possible optimizations of the support system adopted.     

土压平衡盾构机非保压施工技术与应用

以沈阳地铁2号线13标区间盾构隧道掘进为背景,研究分析了土压平衡盾构机在富水的粉细砂、中粗砂和卵砾石复杂地层中盾构掘进,提出了在该地层中盾构机非保压的掘进模式。通过多个盾构施工实例证明采用该模式掘进既可以减少刀盘和刀具的较大磨损,降低总推力和扭矩,避免中途换刀,又可以保证盾构正常安全地施工,该盾构掘进模式可供类似工程借鉴。     

浅埋隧道围岩应力及位移的显式解析解

浅埋隧道施工引起的地层位移将传递至地表进而形成地表沉降,施工前准确预测地层位移是有效控制地表沉降的前提。基于复变函数法,利用逆映射函数求解z平面复势函数的级数形式,并结合柯西-黎曼方程（C-R条件）对Verruijt提出的浅埋隧道围岩应力及位移隐式解析解中的解析函数求导,得出了浅埋隧道应力及位移函数的级数显式表达式;与Verruijt隐式解析解相比,该显式解析解直观,便于被工程人员使用,其编程计算量也较小;为确定显式解析解中的未知系数,基于浅埋隧道洞室变形产生的原因,提出了3种隧道洞室边界的变形模式和2种变形比率,合理调整变形比率可以实现多种边界条件组合。工程实测地层位移与显示解析解的计算结果吻合度高,验证了所提显式解析解的正确性和实用性。     

浅埋软岩隧道式锚碇稳定性原位模型试验研究

为了研究高拉拔荷载作用下浅埋软岩(泥岩)隧道式锚碇的稳定性(强度特性、变形规律及长期稳定性),以某在建的长江大桥隧道式锚碇工程为依托,开展了缩尺比例为1∶10的浅埋软岩(泥岩)隧道式锚碇原位模型试验(蠕变试验、极限破坏试验)。研究发现:浅埋软岩(泥岩)隧道式锚碇具有较高的承载能力,在设计荷载甚至在高于设计荷载几倍的荷载作用的情况下,其蠕变变形呈现出基本上趋于稳定的趋势,具有一定的长期稳定性。其破坏模式为锚塞体上方的岩体破裂成块体状,锚塞体下方沿与岩体接触面产生整体错动,破坏的下边界为锚塞体与岩体的接触带,锚塞体混凝土未发生破坏。此外,还探讨了在高拉拔荷载作用下,锚塞体地表围岩蠕变变形的空间分布规律以及锚塞体地表围岩、深部围岩各部位的变形规律。研究成果可为类似的工程提供参考和借鉴。