Tunneling

In this paper, I present a mapping between representation of some quantum phenomena in one dimension and behavior of a classical time-dependent harmonic oscillator. For the first time, it is demonstrated that quantum tunneling can be described in terms of classical physics without invoking violations of the energy conservation law at any time instance. A formula is presented that generates a wide class of potential barrier shapes with the desirable reflection (transmission) coefficient and transmission phase shift along with the corresponding exact solutions of the time-independent Schr\"odinger's equation. These results, with support from numerical simulations, strongly suggest that two uncoupled classical harmonic oscillators, which initially have a 90\degree relative phase shift and then are simultaneously disturbed by the same parametric perturbation of a finite duration, manifest behavior which can be mapped to that of a single quantum particle, with classical 'ran...

A common framework for interface-trap (N IT ) generation involving broken ≡ Si−H and ≡ Si−O bonds is developed for negative bias temperature instability (NBTI), Fowler-Nordheim (FN), and hot-carrier injection (HCI) stress. Holes (from inversion layer for pMOSFET NBTI, from channel due to impact ionization, and from gate poly due to anode-hole injection or valence-band hole tunneling for nMOSFET HCI) break ≡ Si−H bonds, whose time evolution is governed by either one-dimensional (NBTI or FN) or two-dimensional (HCI) reaction-diffusion models. Hot holes break ≡ Si−O bonds during both FN and HCI stress. Power-law time exponent of N IT during stress and recovery of N IT after stress are governed by relative

We compute the zero frequency current noise numerically and in several limits analytically for the coulomb blockade problem consisting of two tunnel junctions connected in series. At low temperatures over a wide range of voltages, capacitances, and resistances it is shown that the noise measures the variance in the number of electrons in the region between the two tunnel junctions. The average current, on the other hand, only measures the mean number of electrons. Thus, the noise provides additional information about transport in these devices which is not available from measuring the current alone.

An 8.5-mile-long light rail project in Los Angeles included twin 1-mile long tunnels, 21.5 feet in diameter. An Earth Pressure Balance (EPB) Tunnel Boring Machine (TBM) was used for excavating the tunnel in the Late-Pleistocene Alluvial Soils. An automated system was implemented for near-continuous measurement of tunneling induced ground movements from 53 No., Multi-Position Borehole Extensometer (MPBXs). Optical survey was performed to measure ground surface movements. This paper presents the subsurface conditions, the geotechnical instrumentation system, the measured ground movement along the first bored tunnel, and the interpretation of the movement as related to the performance of the EPB TBM and type of subsurface conditions along the alignment.

Foreword

A request was made to the Director General, Geological Survey of Bangladesh (GSB) by The Louis Berger Group, INC and Bangladesh Consulting Ltd. to provide a geological evaluation of Dhaka City for understanding of and planning of underground transportation system under Strategic Transportation Planning Project of the Government of Bangladesh. This evaluation report is prepared using geological investigation reports and technical papers available in the GSB. Emphasis is given to provide some concept on the sub-terrain environment and ground condition of Dhaka city. An interpretation on the engineering geological advantages and disadvantages for planning, designing and development of underground transportation system is done.

Summary

The City of Dhaka occupies a unique geological location in terms of the geological set up and ground condition. Geologically the city landmass is a part of an old terrace that is raised considerably up than the surrounding floodplains. The general elevation in the axial part of the city reaches up to about 6 to 7m above mean sea level (AMSL) whereas the surrounding floodplains are at about 4m AMSL.  The ground of the terrace is composed of Madhupur Clay (Pleistocene), consisting of very stiff to hard, reddish brown, highly ferruginous, plastic Clay-Silt with some minor contents of fine quartz-sand and iron concretions. The shear strength properties are considerably high and the average value of un-drained shear strength is ≈ 2 kg/cm2. The settlement characteristics indicate that the red clay to be an over-consolidated stratum. The geological history indicates that due long run erosion about 20m of materials have been removed from the top of the city ground. This indicates that an amount of ≈ 1 kg/cm2 of vertical stress has removed from the top of the existing ground surface. At present the average thickness of Madhupur Clay in the main urban area is about 7 meters.  The upper clay-silt stratum overlies a firm sand bed, geologically known as Dupitila Formation (Upper Tertiary). The geological and geotechnical properties of Dupitila  Sand (Upper Dupitila  Sandstone) tends to behave as soft rock. This soft sedimentary rock acts as  dense bedrock to hold most of the pile tips of all deep foundation which is uniformly distributed throughout the axial part of the city.

In terms of hydro-geological environment the Madhupur Clay Formation acts a wonderful cap over the Dhaka terrain. The top material is low in permeability and no ground water recharge occurs in the city area at ambient condition. The surface materials and natural topography with unique natural drainage system the flash-flood water has excellent run-off characteristics. The permanent and confined ground water level is located below 70m from the surface. The existing geo-hydrological environment provides better options for underground excavation. 

The existence of Madhupur Clay and Dupitila Sand below the urban feet turns the ground condition of Dhaka city to the best comparing the ground condition of many other cities of the world. Though Bangladesh is located at edge of most seismically active global zone, in terms of the ground condition the apparent seismic hazard* is relatively low in Dhaka city than most of other parts of the country (expected maximum Peak Ground Acceleration is 0.5g). A correlation on Shear Wave Velocity (Vs) of the geological materials underneath Dhaka city indicates that the value of Vs would be > 350 m/sec. Considering the geological and geotechnical aspects, the city of Dhaka has advantageous ground condition for construction of underground engineering structures including underground rapid transportation system.

(*Caution: The low seismic hazard does not mean lower seismic risk, as the risk is directly related to human activity and response to seismic issues.)

Advancement of a tunnel face results in the disturbance and redistribution of the primary in situ stress field. Soil deformation, pore water pressure generation, and induced stress and strain are among engineer's interest. Depending on soil type, rate of TBM machine advancement, and also tunnelling method, soil may behave between the two extreme cases of drained or undrained condition. Understanding soil drainage condition often is not an easy task, however using numerical simulation programs, generated pore water pressure can be estimated and as a result effective and total stress can be obtained. In this paper, a simple procedure has been employed for drainage determination to be used in pre-codded Finite Element Analysis (FEA) program. The method is described and then an Earth Pressure Balance (EPB) tunnelling case study is analysed using proposed procedure. In this case study, two parallel tunnel lines which are being excavated by EPB method interchange with another two subway lines almost perpendicularly. Induced ground movement due to these underground constructions are measured in several locations and then a comparison is made with finite element analysis result.

Spanish Abstract: Ante las crisis, del tipo que sean, economicas, de inseguridad, etc. las personas reaccionan (aumentando el ingreso o modificando habitos de consumo), no queriendo asumir la realidad, para despues convertir sus posibles consecuencias en foco de atencion, generalmente acompanado de la sensacion de perdida de control, tension, miedo y estres. Las decisiones se toman, entonces, a muy corto plazo: efecto tunel. (Dominique Lasarre, 1995). La teoria del “Prozac”, neuroconomia o del que se viene? Surge hace menos de un ano en Estados Unidos como resultado del prolongado ciclo de la actual crisis que ha creado un imaginario negativo en la mente de los consumidores modificando sus habitos de compra, reduciendo volumenes, cambiando marcas y sitios de compra, sustituyendo placeres y conceptos del gasto para constituirlos en ahorro ante un futuro no previsible, es parte de un nuevo imaginario que ahora se asocia a una crisis financiera global acentuada especialmente en paises que suelen ser proveedores a gran escala de demandantes de servicios turisticos de la zona del Caribe y Centroamerica. A su vez, genera un cambio no previsto en la economia familiar de quienes recienten la posible influencia sobre el mercado y la actividad turistica de la region. Plantear posibles alternativas quizas radique en el estudio y aplicacion de la neuroeconomia.English Abstract: Before a crisis, insecure people react by increasing income or by changing consumer habits. They do, not want to face reality, and possible consequences. This is usually accompanied by a feeling of loss of control, tension, fear and stress. Decisions are made in the very short term (Dominique Lasarre, 1995). In the U.S., as a result of prolonged cycle, the current crisis has created a negative imagery in the minds of consumers changing their buying habits, reducing volumes, changing brands and shopping sites, replacing pleasures and concept spending to save before an unforeseeable future. This approach is part of a new vision that is now associated with a global financial crisis accentuated in countries that are usually large-scale providers of tourist services including the Caribbean and Central America. This in turn, generates an unanticipated change in the household economy of those that influence the tourism market in the region. Proposed alternatives may lie in the study and application of Neuroeconomics.

Assessment of risks is a key task in the project management. In this process, Risk Breakdown Structure (RBS) approach can be utilized to identify project relevant risks. In the previous classical method, only Limited number of attributes is considered in the evaluation that can cause unreliable results. In this paper, an attempt has been made to introduce and involve a relatively comprehensive set of attributes for applying in Multi Attribute Decision Making (MADM) techniques. Using this model, the risks of tunneling construction in the Seimareh dam project, located in South-West of Iran, are assessed and ranked. For the collection of experts' judgments, group decision making method by conducting various decision panels was applied. Also for the risk ranking, Linear Assignment (LA), Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) and Simple Additive Weighted (SAW) methods were considered. Final ranking of the risks was computed using integration methods. It was concluded that the risks economical factors and guarantee are the project most and least critical risks, respectively.

This paper provides an overview of some significant aspects concerning the design of concrete tunnel linings subjected to severe fire exposure. The distinguishing feature of tunnel fires is the possible rapid rise of the air temperature within few minutes. The factors that contribute to this phenomenon in combination with the fire duration and the fire spread along the longitudinal direction are cited. Additionally, the widely used fire curves are presented, showing their influence on the predicted temperature profile of a concrete cross-section through uncoupled heat transfer transient numerical analyses. Then, the effect of fire on the concrete behaviour is briefly described with examples from real fire accidents. The focus is on the explosive spalling of concrete, provided that, in general, tunnels are at greater risk than other structures, principally due to the high heating rate and the high initial moisture content. The main features and mechanisms of spalling are presented in conjunction with the available modelling techniques and the design approaches against spalling. Finally, the effectiveness of several passive protection measures is discussed, based on the recent experiences.

Inhalt Vorwort zur Publikation 2018 __________________________________________________ I Der Bau des Gotthardtunnels -viel Geschichte in einer______________________________ I Verknüpfungen und Verflechtungen __________________________________________ II Die Geschichte eines Experiments ___________________________________________ X I Einleitung: Reislaufen nach Göschenen ______________________________________ 1 IX die oft Überlebenserfahrungen waren. 25 Mit Baubeginn zogen Frauen und Männer aus Frankreich und Deutschland, natürlich aus Italien, Österreich, sogar aus Ungarn nach Uri, machten neue Erfahrungen, kehrten zurück in ihre Herkunftsorte, kamen vielleicht später wieder -und so muss man diese Geschichte auch als eine Geschichte von alltagsrelevantem Austausch verstehen, als die Geschichte eines bewegten Hin und Her, das den Bau des Gotthardtunnels ebenso prägte wie dessen Darstellung. Und dann ist es nicht nur die Geschichte von Hiesigen und Fremden, von Handwerkern und Arbeitern, von Ingenieuren und Wirten, es ist auch die Geschichte von Männern und Frauen. In der Geschlechterforschung hat sich die Formulierung etabliert, dass Männlichkeit und Weiblichkeit nicht einfach «sind», sondern dass sie «gemacht» werden. Das bedeutet nicht mehr und nicht weniger, als dass das Umfeld, in dem Menschen leben, die Art und Weise, wie sie sich und andern zu einer bestimmten Zeit und in einem bestimmten gesellschaftlichen Zusammenhang Mann-Sein und Frau-Sein bestätigen oder verweigern, ganz grundlegend Einfluss darauf hat, wie Menschen sich benehmen, wie sie sich kleiden und geben, wie sie sprechen und sich bewegen, welche Berufe ihnen zustehen und welche nicht. Wenn jemand diese Grenzen infrage stellt, indem sie oder er diese konstitutiven Normen übertritt, dann kann das existentielle Folgen haben. Die Tunnelbaustelle als sozialer Nicht-Ort im Sinn von Marc Augé war auch ein Bauplatz für Geschlechterrollen. Ein Beispiel dafür ist die Junggesellenkultur junger piemontesischer Männer, die sich, schwach kontrolliert, ausserhalb der Herkunftsgemeinschaft aufhielten und im liminalen Raum namens Casinotta 26 ihre Versionen von Männlichkeit erzeugten und unter Beweis stellten, sei es in Schlägereien, Trinkpraktiken, in der Zurschaustellung des eigenen Körpers, oder im Umgang mit Schmerz, Krankheit und Todesangst; in grösserer sexueller Freiheit, in der Vernachlässigung von Haushaltführung. Männlichkeit war auch an den Berg 25 Haumann: Lebenswelten und Geschichte, 2012. 26 Casinotta war der Name für Göschenen auf Italienisch.

A shallow urban tunnel for public transportation, built in difficult subsoil conditions with EPB tunnel boring machine, was instrumented to monitor its geotechnical behavior during construction. The parameters that define soil response were measured before, during and after the construction process. Herein the instrumentation used for the tunnel is described, as well as the implementation of new measurement systems. Relevant charts are shown. Immediate tunnel deformations were monitored and used to verify the shield tunneling process. Using the gathered data, correlations were developed to assess the confining influence on the surrounding soil and to describe the stress state during TBM advance. Subsidence on nearby buildings was appraised and related to the grouting support effect. Relevant conclusions regarding instrumentation, grouting and soil subsidence are provided.

Miniaturized Golay cells based on tunneling displacement transducers were first produced at the Jet Propulsion Laboratory (JPL). The devices produced have performance characteristics comparable to the best thermal infrared detectors of comparable dimensions. This work describes a high yield wafer-scale process for fabrication of tunneling infrared detectors. The sensors produced have performance comparable to the best tunneling sensors made so far.

coming a significant contributor to power dissipation of CMOS circuits as threshold voltage, channel length, and gate oxide thickness are reduced. Consequently, the identification and modeling of different leakage components is very important for estimation and reduction of leakage power, especially for low-power applications. This paper reviews various transistor intrinsic leakage mechanisms, including weak inversion, drain-induced barrier lowering, gate-induced drain leakage, and gate oxide tunneling. Channel engineering techniques including retrograde well and halo doping are explained as means to manage short-channel effects for continuous scaling of CMOS devices. Finally, the paper explores different circuit techniques to reduce the leakage power consumption.

Tunneling industry has seen great advancements in underground construction projects. Now, it has significant difference with the last two decades. In many times, tunneling projects find themselves involved in the situation where unexpected conditions threaten the continuation of project. Managers always look for a reliable technique to overcome limitations of finance and time. TOPSIS method is widely used to solve multi criteria decision making (MADM) problems. This technique assigns the best alternative among a pool of feasible alternatives. Furthermore, due to inherent uncertainties in tunneling, using fuzzy logic in order to take into account these uncertainties can be useful. In addition, new factors are introduced to promote the accuracy of risk analysis. Finally, a real world case study is presented to show the effectiveness and the accuracy of the new risk evaluation model. The results demonstrated that collapse is the riskiest parameter in Ghomroud water conveyance tunneling project.

8 marzo 1996 conferenza corso ORGL pag. 2 di 33 EFFETTO MIGLIORAMENTO PER Intervento Materiale Confinamento Resistenza al taglio Deformabilità Infilaggi di protezione, paratie berlinesi Detrito SI Drenaggi Roccia/ Detrito SI Iniezioni cementanti Detrito/ Roccia fratturata SI SI Pretaglio Argille SI Jet grouting Detrito A volte SI SI Bullonatura Roccia fratturata/ Detrito SI SI SI Congelamento Detrito SI SI

When a tunnel is driven, particularly using a TBM, alignment problems can arise, and, with high-speed tunnelling, can get worse very quickly, and so need swift resolution. Changes to the alignment, where possible, are always cheaper and quicker than breaking out newly-built lining. A wriggle survey of the out-of-tolerance lining is the first step, followed by
processing and analysis, followed in turn by judicious re-design of the alignment. The wriggle survey data then needs to be processed again using the new alignment, in an iterative process. This Paper presents some incidents, one from the 1960s, one from the 1980s and some more recent, so that others may learn from the experience.

A trinocular cross-section tunnel with a span of some 50m and a length of about 160m, known as the "Mined Tunnel", is part of the Central-Wan Chai Bypass (CWB), which is a strategic road along the northshore of Hong Kong Island targeted to alleviate the heavy traffic congestion. The most challenging task of CWB project is to construct this 50m combined span of Mined Tunnel directly underneath the portal structure of the existing Cross Harbour Tunnel (CHT) that is a traffic sensitive trunk road already heavily utilised with a daily throughput of about 120,000 vehicles. In April 2015, the excavation of Mined Tunnel was successfully completed, with limited tunnel convergence and displacement recorded at the CHT portal structure as well as the existing building structures in the vicinity. This paper summarises an overview of the comprehensive instrumentation, survey and monitoring system, comprising automatic deformation monitoring system (ADMS), tunnel convergence monitoring, strain gauges, etc, adopted during construction stage. In addition, a retrospective review on the historical movement of the CHT portal structure will be presented. Furthermore, in association with instrumentation monitoring, this paper describes the provisions of precautionary and contingency measures: additional weight on the CHT portal structure and dewatering/recharging system, which were provided to minimise the risk of floatation and settlement of the CHT portal structure.

Ground deformation monitoring in tunnelling is a common means for selecting and controlling the excavation and support methods among those predicted in design, ensuring safety during tunnel excavation (including personnel safety inside the tunnel and safety of structures located at ground surface) and construction quality. This paper describes the types of ground deformation measurement often used in tunnelling, the difficulties in obtaining these measurements, the methods most commonly used for their evaluation, and the use of deformation measurements (a) in the selection of tunnel excavation and support systems and (b) in establishing early warning systems against ground collapse or damage to structures at ground surface.

Due to the quadratic reduction in the switching power dissipation, lowering supply voltage is obviously one of the most e ective ways to reduce p ower consumption. However, the performance will degrade. In order to satisfy the high performance r equirements, threshold voltage has to be s c aled. Unfortunately, such scaling leads to a dramatic increase in leakage current, which becomes a new concern for low voltage and high performance circuit designs. Multiple transistor threshold and supply voltages can be used to achieve low power and high performance while maintaining low leakage current. In this tutorial, di erent multiple-V th , multiple-V dd and standby leakage control techniques are presented.

Uncertainty and variability is part of geotechnical design and need to be taken into account in the design process. This paper presents some of the work in progress of the sub-project of the Australian Centre for Geomechanics' Ground Support Optimisation Project, specifically aiming at advancing risk based support design in mining application. The paper presents some thoughts on a general multi-tiered approach to support design but focuses on its application on only one aspect of the support design process, namely the evaluation of the depth of rock mass yielding. The use of elastic superposition is discussed in more detail as one of the methods to evaluate the influence of the uncertainty of the stress state and to evaluate the depth of rock mass yielding probabilistically. 1 Introduction Due to the uncertainty and variability associated with geotechnical design, it is necessary for geotechnical engineers to develop an appreciation of the influence of these uncertainties and variability on the reliability of the design. Probabilistic evaluation, or in the very least sensitivity analysis, should therefore form part of the design process. This paper presents some of the work in progress as part of the Australian Centre for Geomechanics' Ground Support Systems Optimisation Project. A section of this project aims to not only advance the state of the art, but also to advance the state of practice by providing simple and practical tools to allow mining industry practitioners to implement probabilistic ground support evaluation and to evaluate the effect of uncertainty on the design reliability. The paper is not concerned with an exhaustive ground support design approach but will focus only on one aspect, namely, the depth of rock mass yielding which will of course impact on the decision on support length and type. A multi-tiered approach is necessary to optimise the design by balancing the quality of the results with the effort required to improve the analysis and is presented in this paper. The first level of this multi-tiered approach, namely, using elastic superposition as a tool to explore the boundaries of design problem, is presented in more detail. 2 Multi-tiered approach to assessing depth of rock mass yielding For the purpose of this paper, the multi-tiered approach presented here is focussed at assessing the depth of rock mass yielding, but the approach can easily be extended to incorporate other aspects of the support design. Figure 1 provides a flow chart of a systematic approach to evaluate the depth of rock mass yielding, taking account of the geotechnical uncertainty and variability inherent to the problem.

Uma Oya Hydropower Project in Sri Lanka has a 15 km long headrace tunnel. It is currently excavated by Tunnel Boring Machine (TBM), which is the first use of a TBM in Sri Lanka. In particularly good ground sections, only the invert segment is installed for the operation of the TBM. In the crown, no rock support or rock bolting is applied. In more jointed and worse ground sections, a conventional full ring segmental lining is used. The allocation of lining types is not only determined by the requirement of stability during excavation, but also by the nature of the tunnel as a pressure tunnel during operation. This paper describes the relevance and applicability of different lining types for TBM driven tunnels with special emphasis on geotechnical conditions seen in Central Highlands of Sri Lanka.

The paper presents the geotechnical conditions and engineering properties of the soil types (mainly weathered Athenian schist) encountered during the present construction of the Athens Metro. Measured surface settlements along the Line 3 TBM tunnel and a NATM excavated underground station are also presented and evaluated.

Shotcrete lining is the main supporting element in NATM tunnelling, often used together with rock bolts and steel ribs, forming a composite structure to support the ground.
It sometimes happens that large deformations of the lining are recorded by the deformation monitoring system, with little or no evidence of distress being noticeable in the shotcrete. In other cases, it sometimes happens that conspicuous cracks occur in the shotcrete, but with no significant matching deformation. Such cracks, which prima facie may suggest that a catastrophic failure of the entire supporting structure may be imminent, are frequently found adjacent to steel ribs, at the joint between top heading
and bench, and at other similar locations.
This Paper gives some possible reasons for these two situations in the abstract, investigates possible reasons for the formation of cracks and possible mechanisms
involved, and explores why cracks are not noticed sooner.

Kawasan perkotaan menjadi tempat yang dimimpikan oleh sebagian penduduk luar atau pinggiran kota. Gemerlap kota dan fasilitas-fasilitas lengkap di kota baik dalam bidang pendidikan, kesehatan, ekonomi dan lain-lain menjadi daya tarik kawasan perkotaan. DKI Jakarta yang merupakan Ibu Kota Negara, pusat pemerintahan, sudah tentu memiliki fasilitas yang bisa dibilang lengkap, menjadi harapan hidup sebagian besar masyarakat penduduk Indonesia. Banyak yang berbondong-bondong untuk tinggal di DKI Jakarta, baik untuk kegiatan ekonomi atau lainnya yang nanti akan meningkatkan perkembangan kawasan perkotaan. Keberadaan luasan tanah sebagai sumberdaya di wilayah Jakarta mempunyai nilai luasan yang tetap (fixed land area value) yakni 650 km2 , sedangkan jumlah penduduk yang mendiami dan menetap di wilayah ini setia tahunnya bertambah berdasarkan deret ukur, di mana pertambahan penduduk rata-rata 2,85% per tahunnya (BPS, 2010). Peningkatan jumlah penduduk kota berakibat pada peningkatan jumlah lahan untuk pemukiman dan kegiatan lainnya.

Lahan perkotaan terbatas sehingga terjadi intervensi kegiatan perkotaan pada lahan yang seharusnya berfungsi sebagai daerah konservasi dan ruang terbuka hijau. Akibatnya, daerah resapan air semakin sempit sehingga terjadi peningkatan aliran permukaan dan erosi. Hal ini berdampak pada pendangkalan (penyempitan) sungai, sehigga air meluap dan memicu bencana banjir.

Untuk menyikapi masalah di atas, kami menggagas adanya pembuatan terowongan raksasa (magic tunnel) untuk mengendalikan banjir yang selalu melanda Kota Jakarta.

Tunnels are very important structures which are being used in various construction;like in road, railway for defence purpose and laying of pipelines etc. Tunnels have different shapes on the basis of their uses and the ground conditions and the availability of materials. All tunnels have various degrees of complexity depending on function and safety needs or the code requirements at the time of construction, but most tunnels employ one or many functional systems, such as lighting, ventilation, drainage, fire detectors and alarms, fire suppression, communications and traffic control. With the limited access and confined conditions within a tunnel; the operation, maintenance and inspection of a tunnel must be thoroughly regimented to provide an adequate level of safety for the traveling public. Construction of different types of tunnels include some vary basic operations or steps which are to be folloded in sequence in order to built or to construct a tunnel. This are called basic tunneling operations. This tunneling operations may differ in comparision to older times and this modern time. This paper provides information on tunnels and various tunneling operations involved to make tunnel and also provide information related to old methods of tunneling and new methods of tunneling using ultramodern technology. Some case studies are also there related to the modern technology used tunnel construction.

This article presents results from the first statistically significant study of cost escalation in transportation infrastructure projects. Based on a sample of 258 transportation infrastructure projects worth US$90 billion and representing different project types, geographical regions, and historical periods, it is found with overwhelming statistical significance that the cost estimates used to decide whether such projects should be built are highly and systematically misleading. Underestimation cannot be explained by error and is best explained by strategic misrepresentation, that is, lying. The policy implications are clear: legislators, administrators, investors, media representatives, and members of the public who value honest numbers should not trust cost estimates and cost-benefit analyses produced by project promoters and their analysts.

The instantaneous filling of the annulus that is created behind the segment lining at the end of the tail during the TBM advance is an operation of paramount importance. Its main goal is to minimize the surface settlements due to any over-excavation generated by the passage of the TBM. To correctly achieve the goals, a simultaneous backfilling system and the injected material should satisfy the technical, operational and performance characteristics. A two-component system injection for the back-filling is progressively substituting the use of traditional mortars. In this paper different systems of back-filling grout and in particular the two-component system are analyzed and the results of laboratory tests are presented and discussed.

This paper characterizes earth pressure balance machine (EPBM) torque within the context of a physical model using data from a recent Seattle metro-sized (6.44 m diameter) tunnel project. The paper examines the ability of relatively simple physical models to capture torque, and characterizes relative influence of geology, soil conditioning, pressure and other parameters on measured torque. The physical torque model developed for the analysis grossly overestimates the realized torque by 50 – 500%, even with assumed shear strength reductions of 50% due to disturbance and conditioning. The shear strength reduction required to fit the model with measured torque were 65-70% reduction for sand and 80-85% for silt and clay. INTRODUCTION Cutterhead torque is one of the main driving parameters TBM operators take into account when advancing an EPB machine (EPBM) (Ates et al. 2014). Accurate prediction of cutterhead torque is crucial to the design and operation of an EPBM. In addition, cutterh...

a b s t r a c t RMR is a simple rock mass classification system and is often used for characterization and design purposes in preliminary stages of mining and civil engineering practices. However, the use of RMR in providing a precise predictive model of TBM field penetration index (FPI) is very limited due to the nature of the ratings (weights) assigned to the input parameters and their influence on the FPI. This limitation can be mitigated by using multivariate linear, non-linear and polynomial regression analyses of RMR input parameters. This approach was examined in mostly medium to hard sedimentary rocks in Zagros long tunnel in Western Iran. For this purpose, groundwater condition, because of its poor correlation with FPI, was excluded from determination of RMR and the subsequent analyses. Meanwhile, the angle between tunnel axis and discontinuity planes was included in the model as a substitution of the adjustment factor for discontinuity orientation in RMR. Comparison of measured FPIs with those predicted by the multi-linear, logarithmic and polynomial regression models showed good agreement with correlation coefficients of 0.87, 0.87 and 0.86, respectively. This highlights the potential of multivariate model of rock mass classifications in TBM performance prediction. However, the relationships obtained in this analysis should be considered valid only for geological settings similar to those of Zagros tunnel and more in depth study is required to extend the finding of this study to develop a universal model. This paper discusses previous works in this area, reviews the available data from Zagros tunnel project, methodology for analysis, and introduces a convenient empirical predictive model for TBM performance by using Rock Mass Rating (RMR) system.

The Egyptian tunneling activities have augmented in the last two decades for several purposes such as construction of subways, sewers and road tunnels. The preponderance of the Egyptian tunnels are constructed through soft soils under high ground water pressures in which tunneling can trigger substantial ground deformations. The prevailing subsurface conditions limited the construction methods to full face tunneling machines; otherwise tunneling cannot be proceeding. The Bentonite Slurry Shields proved to be very successful in many mega Egyptian tunneling projects. 
The objects of the present study is to introduce a sophisticated three dimensional numerical model of the Bentonite Slurry Tunneling Machine by adapting the main factors affecting the pressurized Bentonite Slurry Tunneling such as unloading forces due to excavation, ground constitutive nonlinearity, interface condition, engineering properties of shield, rate of advance, machine overcutting, face pressure, yielding zones, the tail grouting and the hardening characteristics of the grout material. Soil constitutive behavior is represented using the hyperbolic elastoplastic model to account for the effect of the stress level, stress path and the confining pressure. Shield and tunnel lining elements are represented by elastic elements considering the different stiffness of the liner and the shield. The interface of the soil-shield and soil-lining is represented by a three dimensional hyperbolic gap element and grouting element with initial grouting stress. Special incremental technique is used to account for the variable mesh size due to excavation and lining erection using pseudo-time technique combined with Newton-Raphson iterative procedure. A nonlinear finite element program was developed and used to analyze the tunneling status in three giant projects, which are considered the foremost Bentonite Slurry tunneling projects in Egypt. The case studies are the Greater Cairo Metro-Line 2, El-Salam Syphon and the intersection of Al-Azhar Twin Road Tunnels and the CWO sewer.
Comparing the results of the developed numerical three-dimensional idealization of the Bentonite Slurry Tunneling with the field measurements compiled during the construction of the studied tunnels indicated the capability of such sophisticated modeling to develop realistic pattern of ground subsidence associated with tunneling. The results implied that, simulating the details of tunneling operation through the modeling formulation is considered as the basis for optimum idealization and is badly needed for realistic updating of the ground tunneling interaction. Furthermore, the three-dimensional tunneling analysis is considered as the entirely capable arrangement to simulate very sophisticated problems such as the intersection of multiple tunnels that cannot be preceded by means of two-dimensional analysis or empirical approach superposition. Consequently, the deformations and the internal forces developed in underground pipelines and sewers due to tunneling can be estimated. The results of the intersection of Al Azhar Road Tunnels and CWO sewer show that pre-excavation grouting proved to be a salutary process to control the deformation and the internal forces developed in underground structures due to tunneling. The results of the numerical modeling of the case studies are compared with the field measurements compiled during tunneling activities in order to assess the proposed numerical model.

Megaproject Planning and Management: Essential Readings contains the seminal articles from the growing body of research on megaproject planning and management along with an original introduction by the editor, Bent Flyvbjerg. The leading and most cited authority in the field, Flyvbjerg has used crowdsourcing and 25 years of experience to cherry-pick from several hundred articles and books the writings that define the field. This volume will be an indispensable source for those wishing to speak with authority about how megaprojects are prepared, delivered, and fought over. The target audience is students, academics, practitioners, and media pundits alike, as well as communities affected by megaprojects.

Back cover text: Megaprojects and Risk provides the first detailed examination of the phenomenon of megaprojects. It is a fascinating account of how the promoters of multi-billion dollar megaprojects systematically and self-servingly misinform parliaments, the public and the media in order to get projects approved and built. It shows, in unusual depth, how the formula for approval is an unhealthy cocktail of underestimated costs, overestimated revenues, undervalued environmental impacts and overvalued economic development effects. This results in projects that are extremely risky, but where the risk is concealed from MPs, taxpayers and investors. The authors not only explore the problems but also suggest practical solutions drawing on theory, experience and hard, scientific evidence from the several hundred projects in twenty nations and five continents that illustrate the book. Accessibly written, it will be the standard reference for students, scholars, planners, economists, auditors, politicians and interested citizens for many years to come.

The alignment of the Udhampur-Srinagar-Baramulla Rail Link (USBRL) Project passes through the Himalayan fold mountain range (Lesser and Higher) situated in Jammu and Kashmir. Tunnel extending from Dharam to Sumbar (T-48) with two adits (A1 & 2) are part of this project, whose design is based on New Austrian Tunneling Method (NATM). T-48 traverses through the metasedimentary succession of the Ramban Formation (phyllite, quartzite, gypsum) of 'Autochthonous Folded Belt or AFB', which is sandwiched between Murree Thrust (MT) and Panjal Thrust (PT). The geological condition encountered during the excavation of A2 was poor to very poor with high water ingress, rocks are overstressed (compressive stress) mostly associated with shears and/or fault zones. Frequent collapses occurred along these weak zones during the excavation due to release of stresses. The impact of thrusting (Murree Thrust) on the rock mass extended up to about 500 m horizontally and this delivered challenges to the tunneling team. Prediction of ground condition was very difficult due to uncertain behavior of ground near and/or around the fault and shear zones. However, the team has been successfully detected and provided supportive measures for safe tunneling.

Ground deformation monitoring in tunnelling is a common means for selecting and controlling the excavation and support methods among those predicted in design, ensuring safety during tunnel excavation (including personnel safety inside the tunnel and safety of structures located at ground surface) and construction quality. This paper describes the types of ground deformation measurement often used in tunnelling, the difficulties in obtaining these measurements, the methods most commonly used for their evaluation, and the use of deformation measurements (a) in the selection of tunnel excavation and support systems and (b) in establishing early warning systems against ground collapse or damage to structures at ground surface. Examples of ground deformation monitoring and their application in tunnel design and construction are illustrated by cases from the Jubilee Line Extension of London Underground [Burland et al., 2001 [Burland, J.B., Standing, J.R. and Jardine, F.M. (2001) bBuilding Response to TunnellingQ Case studies from construction of the Jubilee Line Extension, London. Thomas Telford publishers, London]; Mair, 2001 [Mair, R.J. (2001) bResearch on tunnelling-induced ground movements and their effects on buildings–lessons from the Jubilee Line ExtensionQ, Proc. Int. Conf. on Response of Buildings to Excavation-induced Ground Movements,) and from the 9-km long Kallidromo railway tunnel in Greece. In the first two examples, ground deformation monitoring aims to ensure that structures at ground surface are not harmed by the tunnelling operations. In the third case, the objective is the optimisation of temporary support requirements and early warning against potential collapse.

The article first describes characteristics of major infrastructure projects. Second, it documents a much neglected topic in economics: that ex ante estimates of costs and benefits are often very different from actual ex post costs and benefits. For large infrastructure projects the consequences are cost overruns, benefit shortfalls, and the systematic underestimation of risks. Third, implications for cost–benefit analysis are described, including that such analysis is not to be trusted for major infrastructure projects. Fourth, the article uncovers the causes of this state of affairs in terms of perverse incentives that encourage promoters to underestimate costs and overestimate benefits in the business cases for their projects. But the projects that are made to look best on paper are the projects that amass the highest cost overruns and benefit shortfalls in reality. The article depicts this situation as ‘survival of the unfittest’. Fifth, the article sets out to explain how the problem may be solved, with a view to arriving at more efficient and more democratic projects, and avoiding the scandals that often accompany major infrastructure investments. Finally, the article identifies current trends in major infrastructure development. It is argued that a rapid increase in stimulus spending, combined with more investments in emerging economies, combined with more spending on information technology is catapulting infrastructure investment from the frying pan into the fire.

The objective of installing support is to mitigate the risk of injuries and costs associated with rehabilitation of excavation damage and associated production downtime. It follows that the greater the likelihood of stress damage or rockfalls, due to the inherent rock mass conditions, the more work is required from the support system. In addition to this, the exposure of personnel in these excavations and the quantity of production serviced by the excavation will significantly influence the support requirements. While support systems have evolved over many years to cater for these demands and experienced rock engineering practitioners generally apply appropriate engineering judgement, most design methods are based on a simple factor of safety and do not cater for a proper risk evaluation. In nature, rock mass characteristics are variable and considerable effort is required to understand the variability, particularly when the geology is complex. Stress fields are often unknown or are simply inferred from one or two stress measurements. This paper describes a risk-based approach to support design, which takes the variability of rock mass conditions into consideration. A statistical block stability method is used to estimate the probability of occurrence of rockfalls of different sizes in a given length of tunnel. Elastic and elasto-plastic numerical methods are used to estimate the probability of the depth of failure exceeding a prescribed serviceability criteria. The results of these analyses are used to estimate the expected cost of excavation damage, based on the rehabilitation cost and associated production downtime.

Estimation of advance rate and utilization of tunnel boring machines (TBM) are some of the important steps in planning a TBM tunneling project. Estimation of the utilization factor depends on realistic analysis of downtime components. Among the different parameters influencing TBM downtime, tunnel support is the most influential factor, which can take up to 50% of the total excavation time in some cases. Although, there are some rock mass classification systems specifically developed to link ground conditions with the type and amount of support installed in TBM tunneling, the related downtime for support installation has not been studied in detail. Unit supporting time (UST) is the time required for the installation of ground support per unit length of tunnel. Support installation time (SIT) is the time required for installation of a single ground support element. In this paper, approximate ranges of UST and SIT are discussed and analyzed on the basis of recorded ground SIT from a number of TBM tunneling projects. The primary goal of this paper is to link UST with rock mass classifications that have been specifically developed to assess ground support requirements for different tunnel sections using open-type TBM. An accurate estimate of UST and SIT allows for realistic determination of the related downtime and TBM utilization rate.

O presente trabalho aborda um estudo sobre deslocamentos do maciço devido às escavações de túneis, com ênfase nos deslocamentos verticais superficiais do maciço e na instrumentação geotécnica, destacando sua importância no acompanhamento da execução, visando a segurança da obra e regiões lindeiras. Primeiramente é apresentada uma revisão bibliográfica dos métodos de previsão dos deslocamentos, sendo estes métodos classificados em analíticos, empíricos e semi-empíricos, em seguida, apresenta-se uma relação de instrumentos utilizados para a medição das grandezas físicas relacionadas às obras geotécnicas (deslocamentos, tensões, poropressão etc.); são indicados os principais tipos, suas características e sua aplicação em obras de túneis. Por fim, é apresentado um estudo de caso de uma obra pertencente a um sistema de transporte urbano.

This paper provides an overview of some significant aspects concerning the design of concrete tunnel linings subjected to severe fire exposure. The distinguishing feature of tunnel fires is the possible rapid rise of the air temperature within few minutes. The factors that contribute to this phenomenon in combination
with the fire duration and the fire spread along the longitudinal direction are cited. Additionally, the widely used fire curves are presented, showing their influence on the predicted temperature profile of a concrete cross-section through uncoupled heat transfer transient numerical analyses. Then, the effect of fire on
the concrete behaviour is briefly described with examples from real fire accidents. The focus is on the explosive spalling of concrete, provided that, in general, tunnels are at greater risk than other structures, principally due to the high heating rate and the high initial moisture content. The main features and mechanisms
of spalling are presented in conjunction with the available modelling techniques and the design approaches against spalling. Finally, the effectiveness of several passive protection measures is discussed, based on the recent experiences.

La construcción de túneles y obras subterráneas, ha sido una actividad presente en las principales civilizaciones a lo largo de los siglos. Esta actividad experimentó un gran auge en la segunda mitad del siglo XIX y principios del siglo X con la construcción de los grandes túneles ferroviarios alpinos. En este periodo de tiempo, se realizaron importantes aportaciones tecnológicas como: la máquina de vapor (1814), la máquina de aire comprimido (1849), la dinamita (1867), la electricidad en las minas (1885) y el motor diesel (1898) como más importantes. La calidad en la construcción de túneles, residía en la experiencia práctica adquirida en las minas y en los conocimientos técnicos aportados por una ingeniería incipiente. El control de calidad se realizaba mediante observaciones visuales de técnicos experimentados y la aplicación de técnicas topográficas (1er teodolito 1788) El siglo XX ha sido muy importante en el desarrollo de las técnicas de construcción de túneles, principalmente a partir de su segunda mitad. Los hitos tecnológicos más relevantes que merecen ser reseñados son: El desarrollo de las clasificaciones geomecánicas (1946), la aplicación del Nuevo Método Austriaco (1962), la aplicación del Método Observacional (1964), el desarrollo de Modelos de Comportamiento del terreno y Modelos de Análisis de Estabilidad de los túneles (1967), los Métodos Numéricos de elementos finitos (1967), la utilización de la punta de Widia (1940), la gunitadora (1950), la maquina tuneladora (1951), los escudos presurizados (1974)… En el siglo XX, se construyeron grandes túneles ferroviarios y de carretera como: Frejus y San Gotardo (1980), Seikan (1988), Eurotunel (1994)… El siglo XXI se ha iniciado siguiendo la inercia de finales de siglo XX, aunque hay grandes expectativas en relación con la Industria de la Construcción de obras subterráneas para el presente siglo. Existen varios megaproyectos internacionales que exigirán, en los próximos años, nuevos avances tecnológicos que permitirán la utilización de una maquinaria y de unos métodos constructivos, que acometan con seguridad la construcción y la posterior explotación de los largos túneles ferroviarios submarinos que quieren construirse. Algunos de los futuros proyectos son: El túnel de Gibraltar (2 x 39 Km), el Túnel pirenaico de Vignemale, la conexión ferroviaria transalpina Lyon-Turín, el túnel bajo el estrecho de Bering… Durante el siglo XXI se incorporarán a la construcción de túneles nuevas tecnologías que permitirán construir túneles más largos, en geologías complicadas, aportando una mayor calidad de ejecución con menores costos y plazos de construcción, implantado un sistema de Calidad Global que gestione los riesgos inherentes a los túneles y realice un seguimiento, en tiempo real, de todas las fases del proceso, propiciando la construcción de túneles más seguros y respetuosos con el Medioambiente. Algunas de las principales tecnologías que se utilizarán en un próximo futuro son: La utilización de sensores LVDT (real time), los revestimientos inteligentes, la técnica de visualización geotécnica GVT, las redes de sensores inalámbricos para medición y control WSN, los sistema de alerta y de control integrado inalámbrico, en tiempo real, del proceso constructivo y de las deformaciones y la utilización de materiales más ligeros y resistente con la utilización de los nanomateriales.

A B S T R A C T Settlement control has always been the rst concern for all the participants of shield tunnelling construction fi when the shield machine passes through buildings, especially in urban areas. However, owing to insu cient ffi information communication of the participants, abnormal settlement usually results, against which reasonable settlement control measures are difficult to take. Therefore, a real-time mobile interaction and coordinated management platform was designed and developed with the instant messaging (IM) tool. The key ingredients of the platform are timely auto-sending of monitoring data and information ow in the coordinated management fl mechanism. The platform can inform all participants timely of the settlement as well as the tunneling situation. With this platform, problems encountered during shield tunnelling construction can be solved by IM group discussion. The real-time interaction platform has been validated and veri ed in the project of Nanning metro fi line 1 crossing beneath Nanning railway station, which realized the settlement control goal of a maximum value of 4 mm. −