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By S. Tuylu, D. Adiguzel, A. Bascetin, O. Ozdemir, U. Cinar

"In recent years, use of mineral processing tailings as a paste backfill has been significantly increased due to the environmental problems occurred during the disposal of the tailings in mine area. The paste material used to fill the stopes excavated is generally consisted of tailings (solid ratio: 70–85%) and cement (3-7%w/w). Meanwhile, the strength of the paste material is completely related to ratios of these materials. Cemented Paste Backfill (CPB) system is used as support depending on the roof pressure and also as an underground disposal method. Therefore, temporary strength value of the paste material gains a great importance. For example, the paste backfill material must compensate the minimum 4 MPa strength value in order to procure the permanent fortification, and the mixture cost must be minimal as well. For this reason, in this study, the Pb-Zn tailings were used to prepare for the paste backfill material using cement in order to perform the uniaxial compressive strength (UCS) tests. Additionally, a statistical experimental design and linear programming techniques was used to find the optimum mixture in terms of strength and cost. The pulp solid ratios (PSR) of the tailings and cement (by the solid) were varied as 75-85% and 3-8%, respectively. The results of this study; the optimum mixture is ~79.5%PSR and 6.8% cement ratio (by the solid) for 4 MPa UCS (28 day) and 16-17 cm slump value determined by this method with statistically reviewed experimental data. INTRODUCTION Fine-grained tailing waste materials resulting from mining activities are an important environmental problem. In terms of environmental protection, the use of tailings with paste backfill is a very attractive approach and a desirable solution to tailings management. Paste backfill, which is used to fill underground openings, is made by primarly mine tailings mixed with hydraulic binders and water. Its main benefits are not only disposal of mine tailings in underground, but also providing a certain strength to ensure a safe working environment. Therefore, it is necessary to use hydraulic binders due to durability of the system (Benzaazoua et al., 2004). Paste backfill, formed from the mix of dewatered plant tailings (75-85 wt. % solids), water and binder (3-8 wt. %) (Brackebusch, 1994; Landriault et al., 2005).Water is used to determine the chemical reactions between tailing and binder materials for strength as well as increasing pumpability. Portland cement and ash can be used as binder materials (Douglas and Malhotra, 1987). The factors which affect strength and stability of paste backfill separate into two groups called interior and exterior factors. Interior and exterior factors determine the strength, stability and deformation features of backfill in short and long terms and also affect the transportation of backfill to underground (Benzaazoua et al., 2004; Erçikdi et al., 2006; Yilmaz et al., 2010; Nasir and Fall, 2010). Material properties of tailings as well as site operations to fill the underground openings are the most important steps for the design purposes. Grain size distribution, chemical, and physical properties of tailings, and mechanical properties of paste fill material are used to understand the suitability of tailings as paste fill material (Ozturk et al., 2014). In addition, Fig. 1. is also proposed to apply a typical design for the operational stages of paste fill applications on the site."

Jan 1, 2016

By S. Tuylu, D. Adiguzel, A. Bascetin

"Optimization techniques are successfully used in many different fields such as engineering, physics, economy, and politics in order to enhance the performance of the systems. In concrete technology, Aggregates are prepared by mixing the water and cement in proportional quantities. In order to obtain desired quality control parameters, the determination of the ingredients ratios is one of the important problems for the optimization. Additionally, in the quarries where the aggregate quality constantly changes, blending optimization must be made to obtain a sustainable aggregate quality. This study showed that linear programming, which is easy and which includes many aggregate properties, cannot be used in terms of some aggregate properties. Therefore techniques such as nonlinear programming or genetic algorithm must be used. INTRODUCTION Concrete is a used construction material and made by mixing the aggregate, cement, and water. The concrete properties are directly related to the properties of these materials in blending. The quantity of aggregates in concrete is approximately 70 percent of the concrete’s volume. Therefore, the most important material is aggregates. The extraction of aggregate materials in quarries is more problematic because of variable bedrock properties. Therefore, the quality of the materials changes and the characteristics of the concrete are also influenced directly. In terms of sustainable use of natural resources, produced aggregate materials which have different qualities should be used optimally (Adiguzel et al., 2014). Nowadays, in the solution of the blending optimization, various optimization techniques are being used such as linear programming, nonlinear programming, and genetic algorithm. In this study, blending optimization techniques especially used for concrete aggregates blending have been summarized, and the advantages and disadvantages of these techniques have been introduced. BLENDING PROBLEMS Blending is a frequently encountered problem in process-type manufacturing such as mining, refinery, food industry, chemical industry and metal industry (Sakalli 2010). Blending is a commonly used method in lots of practical solutions (Sarker and Newton 2008). Several optimization techniques are available for blending problems (Furman and Pardalos 2009). The most important issue is to blend with minimum cost. The blending problem is a special linear model which was developed to solve this problem. In blending optimization research, linear programming is a widely used method (Adiguzel et al. 2011; Bascetin and Adiguzel 2011)."

Jan 1, 2016

By Peter Johnson, David Barber, Lachlan Henderson

"The traditional approach to rail tunnel fire safety design is to follow NFPA 130, which assumes a major tunnel fire could occur and requires bi-directional emergency ventilation. There is no regard to the impact of ventilation on fire growth and smoke production. In Europe and other parts of the world, the need for tunnel ventilation systems to provide smoke management in the event of fire is being questioned. The European Commission’s Safety in Railway Tunnels TSI is based on a philosophy that improved running capability (preventing fires and other events stopping the train in the tunnel) and elevated fire performance of materials means the chances of a major fire in a tunnel is highly unlikely, with only small fires expected, and no tunnel ventilation required. This approach is reinforced by the International Tunneling Association which has recently published an Engineering Methodology for Performance Based Fire Safety Design on Underground Rail Systems, which includes a methodology that does not require assessment of tenability in tunnels, but requires a scenario based risk assessment to be undertaken to determine overall fire safety measures. Recent research by the University of Edinburgh has shown that forced airflow from a mechanical ventilation system may promote fire growth and increase smoke volumes much more than with natural ventilation. Whilst the concept of no mechanical ventilation (i.e. natural ventilation) is a new concept for some, for many rail tunnels it is worthy of serious further consideration. RAIL TUNNEL SMOKE MANAGEMENT AND STANDARDS Smoke management using mechanical bi-directional ventilation systems has been a central part of the fire safety design solution under NFPA 130 for rail tunnels since 1982. The current version of the standard, NFPA 130: 2014, states that mechanical ventilation should be fitted to rail tunnels of length greater than 305 meters and an engineering analysis should be undertaken for tunnels of length 61 to 305 meters to determine whether mechanical ventilation should be fitted. However, this approach is not necessarily reflected elsewhere in the world. In Europe in particular, mechanical ventilation systems for smoke control within rail tunnels have taken a much less central role within the standards framework."

Jan 1, 2016

By R. Venugopal, V. K. Saxena, A. K. Mukherjee

"Coal, iron and manganese ore samples were exposed to different ultrasonic intensities of 250, 300 and 350 W/L for five minutes and to an ultrosonic intensity of 270 W/L for different time durations of 3, 5 and 7 minutes. The ultrasonically treated samples showed reductions in D80 particle diameters of 6 percent for the coal samples, 5.95 percent for the iron ore samples and 35.63 percent for the manganese ore samples during grinding. The ultrasonic treatment was also observed to assist in reducing ash content in the coal product by 8 percent and to reduce manganese losses in rejects by about 5 percent. Ultrasonic treatment was concluded to be capable of assisting in the comminution of friable ores more prominently than the hard and porous materials.IntroductionComminution is an important unit operation in the mineral-processing, cement-making, powergeneration and pharmaceutical industries. But most of the milling technologies are considered to be energy inefficient, with less energy consumed in real size reduction and most of the energy consumed in the machine. This is more critical for the mineralprocessing industry because of the growing need to exploit lower-grade ore bodies and process rejects (Blazy et al., 1994; U.S. Department of Energy, 2005). Low-grade ores require crushing and grinding to liberate the valuable minerals, which are further separated from gangues by various beneficiation methods such as gravity separation, flotation and leaching. Various studies have been carried out to minimize energy consumption during milling by developing pretreatment methods that can initiate new fractures or improve the fracture density in materials before comminution. These studies were mainly focused on chemical additives; thermal, ultrasonic and microwave treatments; and electric disintegration (Klimpel and Austin, 1982; Norgate and Weller, 1994; Bearman, Briggs and Kojovic, 1997; Gaete-Garreton, Vargas-Hermandez and Velasquez-Lambert, 2000; Kumar et al., 2010; Wang, Shi and Manlapig., 2011, Singh et al., 2012).The fragmentation effect of ultrasonic fields in solids has been investigated since the 1950s, and Gärtner was probably the first researcher who attempted it (Gaete-Garreton, Vargas- Hermandez and Velasquez-Lambert, 2000). Sound waves can propagate in solids in the form of longitudinal waves, shear waves and surface waves, and in thin materials as plate waves.In surfaces, fractures and interfaces, various types of elliptical or complex vibrations of the particles make other waves possible. During ultrasonic-vibration treatment, cavitation bubbles nucleate, grow and collapse, generating microjets, whose impacts on the particles initiate microcracks. The ultrasonic waves can enhance the nucleation, growth and coalescence of flaws, caused by tensile or shear stress. The mechanisms operating in the materials and inducing these stresses have been identified as spall and compression-induced tensile microcracks, nucleating at preexisting flaws. These mechanisms are driven by the shock wave and cavitation effects in the surrounding fluid (Chen, Huang and Shih, 2003)"

Jan 1, 2016

By I. Y. Bausov, L. G. Stolarczyk, R. E. Pillmore, A. J. Hillard, J. T. Duncan

"Prevalence of lung disease in younger miners surprised industry regulators, congressional members, researchers and black lung clinic staff members. Mitigation researcher focused on low-coal mining in the Appalachian regions until Miners Colfax Medical Center (MCMC) Black Lung Clinic examinations discovered 25 of 72 Wyoming coal miners with lung disease. To reverse recent upward trend in lung disease, research programatic have been directed at reducing exposure to respirable “float” dust. This paper suggests broadening the scope of research to include boundary detection in efforts to improve outcomes. Beginning with a better understanding of biochemistry of anaerobic bacteria methylation processes precipitating sulfur and heavy metals into thin seam boundary layers. Expanding research and development objective to focused on minimization of bit-pick crushing cone volume and preventing mining thin boundary coal layers and out-of-seam dilution. Black lung clinical evaluations of miner will confirm outcomes directed towards reduced occupational disease and smoke stack emissions. INTRODUCTION Miner exposer to bit-tip crushing cone volume, fragmentation and auger movement generated respirable “float” dust and boiler emissions are related science-technology –engineering-mathematics (STEM) problems. Formidable but not intractable problems are driven by oxidation of upper flood plain elements in the periodic table and biochemical metabolic presses occurring in coal basin. Because of burial compaction, quartz and trace heavy metals (Fe2+, Mg2+) are concentrated in thin seam boundary layers. By not cutting through thin boundary coal layer and out-of-seam into hard quartz containing rock layers, miner lung disease and smoke stack emissions are minimized. Cutting bit-pick elastic wave hydrodynamic principle force vectors in the coal layer must be aligned to minimize respirable dust generation, constrained by fragmentation size. Dust abatement by water spray and machine design are effective; but for, failure to address cutting cone dust volume generation and its distribution along run-of-mine (ROM) transportation systems the boiler. Real-time precision thickness measurements by integrated cutting drum (icDrum) sensor, machine man-interdiction from a dust free control room, is a cost effective way to prevents respirable dust exposure. The recommended STEM research and demonstration initiative addresses issues raised by discoveries of increased rate of lung disease discovered in young miners and concerns over emissions from coal-fired electric generation stations (Global Warming). In-mine demonstrations must be validated by on-site MCMC mobile Black Lung Clinic data acquisition and analysis."

Jan 1, 2016

By James Wonneberg, William Edgerton

"Today’s underground construction megaprojects are tremendous feats of engineering on a massive scale, excavating through ground conditions once thought impossible, using new and innovative contracting practices. But one important truth remains unchanged; projects are built by people. What separates winning projects from the rest? Great people, working in great organizations. In straight-talk fashion this paper sets forth fundamental differences between good project leaders and bad ones, on topics ranging from client relations, design management, and scheduling, to use of the whiteboard, and everything in between. Broadly applicable to all corners of project delivery, this paper will resonate with project leaders from around the world and help identify skills necessary to succeed in the management of underground facilities. A NOTE FROM THE AUTHORS This is a training document, and not really a “paper” per se. We have attempted to tackle some big and potentially complex topics using bite-sized paragraphs, each of which are intended to promote thoughtful introspection and dialog. So please feel free to skip around, or even set this document down while you reflect on your own personal experiences, tactics, and philosophies. We have found that providing examples of “what not to do” is oftentimes more instructive than simply listing “what to do”, hence the Good/Bad format of this document. Please note that “PM” refers loosely to anyone on the project management team not just the “Project Manager”. We also wish to preface this with the following cautionary statements: • The authors do not pretend to be the “Good PM” in all cases. In fact, we’re almost certainly the “Bad PM” for some. We aim to improve on those areas. • It has been said that “The only real training for leadership is leadership.” (Antony Jay) We all started somewhere, and nobody has 20 years of experience on day one. • Converting this text into some sort of prescriptive checklist would be a disservice to the evolution of project management. Our world – and our awareness of it – is constantly changing. We must always be open minded to new ideas and different perspectives on project delivery."

Jan 1, 2016

By Thomas Schwind, Benedikt Grau, Angelos Gakis

"In Crossrail’s Farringdon station, compensation grouting was successfully utilized to mitigate the surface settlements induced by the tunneling works. The main focus of this study was the platform tunnels, which were approximately 300m long each and were enlarged to platform size using sequential excavation method (SEM) from the existing TBM running tunnels, initially supported using sprayed concrete linings. The rear grouting injections were carried out at a typical distance of minimum 5m above the completed, fully strengthened shotcrete lining hence inducing some additional stresses. In-tunnel monitoring using surveying targets was performed systematically to ensure that no excessive distortion of the initial shotcrete lining occurred. 3D finite element analyses were utilized to back calculate the actual “effective” pressure that was imposed on the completed shotcrete rings against the additional measured in-tunnel displacements due to the compensation grouting episodes. Additionally an assessment of the theoretical, “maximum” allowable grouting pressures that would lead to overstressing of the lining is presented. INTRODUCTION As part of the back analysis performed for the SEM tunnels in Farringdon station, an investigation of the effect of compensation grouting on the two constructed platform tunnels was undertaken. The platform tunnels were 10.6m high by 11.4m wide and approximately 300m long each. They were enlarged to their final shape from the existing TBM tunnels using SCL methods. This study utilized 2D and 3D finite element (FE) analyses in order to back calculate the observed tunnel crown displacement, assessing the equivalent grouting pressures during the rear injection episodes of the concurrent grouting operations. The results provide a useful reference for the order of magnitude of the grouting pressure load cases that can be applied in the numerical simulation of similar cases. Part of the results presented in this paper, were derived by the second author as part of his Master of Science thesis in Technical University of Graz."

Jan 1, 2016

By Matthew Grzelak, Gulsah Erinc, David R. Chapman

"The third phase of the Bagram Drainage System project at Bagram Air Force Base in Afghanistan included construction of a shallow, 540-m long, 1.8-m inside diameter drainage tunnel. The tunnel penetrated mostly stiff to hard clayey and silty soils. The contractor’s Value Engineering Change Proposal (VECP) to use pipe-jacking with a microtunnel boring machine (MTBM) instead of the specified two-pass Earth Pressure Balance method was evaluated and supported using hand calculations. Contractor support was provided throughout the project by providing design reviews and instrumentation monitoring during construction. This paper compares the value-engineering proposal to the specified method and describes the construction conditions encountered. INTRODUCTION As part of a larger improvement project at the Bagram Air Force Base in Afghanistan, a shallow, 540-m long, 1.8-m inside diameter drainage tunnel was constructed to provide additional capacity for Coyote Creek to pass below several critical structures, including taxiways and the main runway, for mitigation of recurring flooding (see Figures 1 and 2). Overburden over the tunnel crown ranged from about 3 m to 5.5 m. An existing cast-in-place twin barrel concrete culvert runs approximately parallel to the new tunnel and is within about 8 m at its closest point. The contractor’s Value Engineering Change Proposal (VECP) to the specified two-pass Earth Pressure Balance (EPB) method (steel ribs and lagging or steel liner plate with a carrier pipe later grouted in-place) called for installation of the required drainage pipe by pipe-jacking (one-pass installation) using a slurry microtunnel boring machine (MTBM). The critical nature of the operations at the air base resulted in significant construction coordination challenges and a greater than usual need to avoid excessive settlements. Substantial restrictions were placed on drilling of investigative borings and installing instrumentation near runways and taxiways due to drill mast height. The prime contractor was SERKA TAAHHUT INSAAT A. S. (SERKA), the microtunneling subcontractor was Ludwig Pfeiffer Microtunnel GmbH & Co.KG (Pfeiffer), the jacking pipe designer was Gollwitzer Pipe and Shaft Technology GmbH (Gollwitzer), and the contractor’s tunnel engineer was Lachel & Associates, Inc. (Lachel). Lachel provided contractor support throughout the project including preparation of a VECP/Design Summary (including interpretation of existing and new geotechnical information), design reviews for jacking pipe, estimating settlement of an existing drainage structure above the new tunnel, and instrumentation planning, monitoring, and analysis during construction."

Jan 1, 2016

By Robin Dill, Wei Song, Andrew Perham, Leo Martin

"AECOM completed a subsurface exploration program for an 18-foot diameter, approximately 4-mile long rock tunnel project in Hartford, CT. The tunnel crosses the regional geologic trend through the middle of a sedimentary basin, passing through four separate rock formations, including two volcanic flows. Faulting is prevalent, with at least 15 faults encountered during the site investigation. Severe artesian flows were also experienced in several of the borings, requiring highly specialized drilling equipment. Sixty-two borings and associated testing were performed to characterize the structural geology, hydrogeology, rock properties and ground conditions. A phased program was carefully planned and implemented with participation of geotechnical and geologic specialists, with thoughtful evaluation along the way to react to the ground conditions encountered, and make appropriate refinements. This paper will discuss the subsurface program details; the integrated efforts used to effectively characterize the ground; and will summarize the final characterization presented in the GBR. PROJECT DESCRIPTION The South Tunnel Conveyance and Storage Tunnel project is part of the Metropolitan District (MDC’s) Long Term Control Plan to address discharges to various water bodies throughout the greater Hartford area. This program includes a main conveyance and storage tunnel; a tunnel boring machine (TBM) launch shaft and retrieval shaft; adit tunnels with associated drop shafts and connection structures; consolidation conduits and manholes; and a tunnel pump station (TPS) at the downstream end of the main conveyance tunnel. AECOM is serving as prime designer for the MDC on this project. The main conveyance tunnel (hereinafter referred to as the “South Tunnel”) will be a deep rock tunnel with an invert depth of approximately 180 feet at its downstream end and approximately 218 feet at the TBM retrieval shaft. The tunnel will have a finished diameter of 18 feet. The tunnel will rise in grade at a slope of 0.1 percent to its upstream end. Total invert depth along the deep tunnel alignment ranges from about 180 ft. to as high as 320 feet. The total length of the tunnel will be 21,754 feet. The South Tunnel will be constructed using a shielded TBM and fully lined with pre-cast concrete segments."

Jan 1, 2016

By Dimitrios Litsas, Michael Kavvadas, Panagiotis Sitarenios

"The paper discusses the results of 3D finite element analyses to investigate the effect of face support pressure and soil permeability on face stability conditions in EPB tunnelling. Two main types of face behavior are identified: Undrained conditions ahead of the tunnel face, typically occurring in soils with permeability less than about k=5·10-7m/s, are shown to be favourable for face stability; analyses show that an applied face pressure comparable with the initial hydrostatic pore pressure is sufficient for adequate face stability, even for soils of relatively low strength. Drained or partially conditions, typically occurring in soils with permeability higher than about k=5·10-6m/s, show that face stability is strongly dependent on the horizontal effective stress of the muck in the excavation chamber; the presence of even a small effective stress in the muck is very beneficial for face stability conditions and can be a possible explanation of successful EPB tunnelling through relatively permeable soils. INTRODUCTION Face stability is probably the most important aspect in urban tunnelling. Usually, Earth Pressure Balance (EPB) machines are utilized, to ensure that a reasonable amount of face pressure is exerted on the advancing excavation face, reducing ground loss and preventing potential instability of the face core, thus controlling the amount of disturbance caused by tunnel excavation to surface structures. However, the ideal amount of face pressure depends on several factors (ground and groundwater conditions, tunnel size and depth, muck conditioning, etc.) which are difficult to include in analytical calculations. For many years, conventional empirical or analytical methods (e.g. Anagnostou & Kovari 1996) were the only available tools for quantifying face stability and selecting the required face pressure. In the last few years, however, numerical analyses have gained power over conventional methods, allowing more accurate designs and providing useful information about the anticipated ground deformations due to tunnelling. Numerical analyses have also been used in assessing safety against face instability using face extrusion (horizontal face displacement) calculations (e.g. Prountzopoulos 2012)."

Jan 1, 2016

By Marco Aurelio Piangatelli, Massimiliano Bringiotti, Ferdinando De Angelis

"The construction of the three connecting tunnels between the east side and the west side of station C13, adjacent to the Vistula river, has a long and complex history, as they cross beneath one of Warsaw’s main road arteries (Wislostrada). After the attempt to excavate the first tunnel, the face of the tunnel collapsed on the night of August 13, 2012, and a volume of about 10,000 cubic meters of liquid mass (water, silty soil and sand) entered and flooded the west side of the station, which was filled with more than seven meters of material. Fortunately, the workers managed to escape, but machines and equipment were lost. This is the story of how the tunnels were completed, by adopting soil improvement, jet grouting, GRP bars, ground freezing and a careful choice of work steps. INTRODUCTION The Centrum Nauki Kopernik station on Line II of the Warsaw Underground is located alongside to the Vistula river (Figure 1). This station hereinafter is referred to as station C13.The station consist of three parts: the east and west part, and three connecting tunnels 40 meters in length with a large cross section (170 m2).. It includes the rails along the sides and the platform along the centre. The reason for the underground connection of two shafts with a tunnel is due to the presence of a road tunnel (Wislostrada, hereinafter called WS), which must be underpassed by the new metro line (Figure 2).The existing tunnel (Wislostrada) was built many years before, between diaphragm walls, and some foundation structures interfere with the underground tunnel. The challenge was to build the connectors without stopping the traffic of vehicles along the highway above. All works took place in very difficult geological and groundwater conditions due to the presence of Vistula alluvial deposits with poor mechanical characteristics. The soil profile consists of relatively loose sands on top, and silts overlying high plasticity Pliocene clays highly disturbed by the effects of the repeated over-sliding of glacial moraine deposits."

Jan 1, 2016

By Shinichi Konda, Gary Nishimura

"Thousands of years ago large glaciers carved much of the landscape in Puget Sound, depositing abrasive and granular soils including cobbles and boulders along with layers of clay and sand. Tunneling in this geology – common throughout much of the northern and Midwestern U.S. – is challenging and can be unpredictable. The use of pressurized face tunneling, most commonly with EPBs and slurry type machines, has made excavation in this geology more efficient, but difficulties still remain. Through analysis of recent projects in Seattle, Washington, USA, the authors draw conclusions as to the best TBM designs and operational parameters for this variable, abrasive and often difficult ground. Performance data is analyzed with an eye towards advancements that could further improve TBM tunneling in glacially deposited soils. INTRODUCTION Over the past several ice ages, extensive glaciers reaching across much of North America transported large amounts of soil and rock as they moved across the land. The substantial weight of the ice sheets mixed together a wide range of soil types along with a variety of rocks and boulders of all sizes. Many rock formations were reduced to pebbles or particles containing highly abrasive characteristics. Any boulders able to survive were generally comprised of harder materials which were scattered throughout the soil. This highly variable mixture of abrasive soils and high strength boulders can be found in many areas across the Puget Sound and other regions of the country. Wherever they are encountered, they often create a difficult and unpredictable mining environment for both equipment design and operation. Modern TBMs are optimized early in the design process for specific types of geology, and unexpected conditions can require extensive modifications. In addition, several operational parameters need to be adjusted to balance ground characteristics, and advance rates can be significantly affected in mixed and rapidly changing soil conditions. Both EPB and slurry machines can be used successfully in these conditions, provided their respective operating criteria are met. Ideally, an EPB is operated with a relatively thick muck consistency, which accommodates moderate changes in soil permeability and maintains a reliable pressure differential through the screw conveyor. However, this also causes higher wear on rotating components and requires more energy at the cutterhead. Alternatively, slurry machines typically operate best with a more fluid muck consistency that can be easily pumped through the extensive piping system. This tends to reduce the wear on the cutterhead and the power requirements of the cutterhead drive system, but also makes the machine more sensitive to changing soil conditions. Generally, the slurry piping system is also more capable of controlling high face pressures, although the screw conveyor of an EPB can also be designed to accommodate most high-pressure conditions."

Jan 1, 2016

By Matthew Wilcock, Kenichi Soga, Peter Wright

"This paper discusses how an existing grey cast iron segmental tunnel lining responds to construction of a new SCL tunnel transversely beneath with zero clearance; how the damage assessment for the existing tunnel was conducted for impact of longitudinal movement; how the tunnel is subsequently instrumented to observe both movement and stress manifestation at its longitudinal connections and how the results from the instruments compare with the prediction. An assessment of neutral axis of the tunnel in longitudinal flexure is also explored using interpolated horizontal displacement data from a conventional monitoring system. INTRODUCTION The Royal Mail Tunnel (RMT) (formely Post Office Tunnel or ‘Mailrail’) was constructed using semi-mechanised deep level construction techniques from 1914 and 1917 (Lee 1938). Commencing full commercial operation in 1926, the system was until 2003; conveying parcels the 6.5 miles between seven sorting offices in the center of London, and linking the system with main line rail stations, Paddington and Liverpool Street (The British Postal Museum & Archive 2013). A single tunnel of 2.74m internal diameter facilitated a bi-directional twin narrow-gauge (~611mm gauge) railway road system for electric driverless operation. The tunnel lining is segmental grey cast iron (grade 10) made up of six flanged segments and a smaller flanged key segment; constructed into a ring of width 508mm The external diameter of the tunnel is 2.971m. For further details of the tunnel lining and material properties are outlined by (Devriendt & Alhaddad 2014).London Underground Bond Street Station is a major station of the London Underground system in the very center of London; in its vicinity, the RMT runs west-east perpendicularly above the north south Jubilee Line tunnels. Historic survey record of the Jubilee Line’s (the then Fleet Line) construction in 1974 and its impact on the RMT case is documented in (Crossrail 1993): it is one of only a hand full of case-studies frequently cited when assessing the impact of new construction scenarios of this type; not least including the assessment of the same tunnel, at the same site some 40 years later, and the subject material for this paper: It noted significant vertical displacement of ~90mm to the RMT without noticeable serviceability or operational impediment."

Jan 1, 2016

By Anne Kathrine Kalager

"Stretching from Norway’s capital, Oslo, to the city of Ski, a new railway line is under construction with a 20 km long hard rock tunnel. This is a major project with high demands regarding quality, cost and schedule. In addition, restrictions concerning locations close to sensitive urban infrastructure require execution with the highest level of precision and expertise. The new double track railway line forms an important part of the intercity rail development southwards from the capital and includes the longest railway tunnel to date in the Nordic countries. With its novel methods and solutions, this project offers a model for future railway project developments in the region. This paper provides general pertinent details and facts relating to this current railway project and includes a description of the project with information relating to concept and design of the tunnels, geological conditions, particular challenges, selected tunneling techniques and contracting strategies. THE FOLLO LINE PROJECT The Follo Line is a new 22 km long double track railway line under construction between Oslo Central Station and the city of Ski. The project is divided into four subprojects, as shown in figure 1. The main part of the project consists of a 20 km long hard-rock tunnel, which will be the longest railway tunnel in the Nordic countries to date.The Østfold Line is the existing double-track railway line running between Oslo Central Station and Ski serving 12 local stations. The new Follo Line will offer a direct service, without stops, between Oslo Central Station and Ski and reduce the travel time from 22 minutes to 11 minutes. After completion of the Follo Line, these two railway lines will, in combination, more than double the capacity for train transport in the region south-east of Oslo."

Jan 1, 2016

By Klaus Rabensteiner, Klaus Chmelina

"INTRODUCTION Urban tunneling is often related with special geotechnical risks. Typical causes are difficult (hydro)geological conditions, a very low overburden and the presence of critical and vulnerable (infra)structures in the influence zone of the construction (e.g. existing tunnels, roads and pavements, sewer pipes, gas and power lines, landmarked buildings, historic monuments). To manage these risks appropriately, an early detection and warning of unexpected behavior of the affected geotechnical objects ground and tunnel, as well as existing structures are mandatory. To accomplish this, the design and execution of a dense geotechnical monitoring program is of high importance. In more detail, this means specifying and performing a systematic and continuous acquisition, processing and analysis of monitoring data to support decision making. In recent years the development of new automatic sensors and (wireless) data transfer techniques and the general trend towards an automatic acquisition of monitoring data has led to an enormous increase of data production frequencies and volumes. In order to handle this data explosion efficiently, information systems and geo-databases have been developed and used successfully in many projects. They represent IT tools that support the different tasks of a given geotechnical monitoring program including data acquisition, transfer, check, processing, backup, analysis, distribution, reporting and, last but not least, alarming. Meanwhile, some tools already have developed the capability to connect to other theme-specific databases used in the project and, thus, serve as a central data management system for all kind of digital data produced. This makes possible the implementation of further useful functions and services supporting tunneling tasks such as machine control, tunnel simulation, geological prediction, process optimization, etc. where data from different engineering disciplines must be combined and processed in an integrated way. In the following chapters our aim is to describe how monitoring data management, geotechnical monitoring, alarming and reporting are organized and technically implemented at the metro project Cityringen in Copenhagen (Denmark). We want to highlight the specific role and tasks of the used tunnel information system in the project, and particularly inform on the most relevant challenges."

Jan 1, 2016

By K. V. Raj

"The development and advancement of computational fluid dynamics (CFD) has made it possible to better understand pollutant flow and distribution in deep open pit mines. Open pits located at higher latitudes, especially in the Arctic and sub-Arctic, face a unique problem due to atmospheric temperature inversion, which is prevalent during much of the winter. A three-dimensional CFD model of an actual open pit mine in the Arctic was developed to analyze the problem of pollutant growth during inversion, and mitigation of the pollutants through improved ventilation schemes. Due to the availability of mine-specific data, such as contaminant concentrations and coordinates of sampling locations, the actual 2013 pit geometry was used for model validation Concentrations predicted by the selected realizable ?-e turbulent model are compared to measured pollutant concentrations at the open pit. Pollutant concentrations at selected locations showed differences, but remained within the same order of magnitude in most cases. INTRODUCTION Computational fluid dynamics (CFD) has emerged as a useful tool for ventilation modeling in underground mines (Edwards and Hwang 1999, Purushotham and Bandopadhyay 2009, Wala et al. 1998, Xu et al. 2011). Application of CFD in open pit mines has been limited, however, since most open pit mines located at lower latitudes do not encounter considerable ventilation problems. Open pits located at higher latitudes, especially the Arctic and sub-Arctic, face a unique problem due to atmospheric temperature inversion, which is prevalent during winter. A number of Russian researchers have tried to understand the air inversion and resulting pollutant transport problem by modeling air flow phenomena in open pit mines (Baklanov and Burman 1996, Baklanov 1984, Baklanov 1995, Belousov 1985, 1989, 1995). Much of their work, however, was based on numerical models and methods of finite difference. Baklanov (2000) applied a modified ?-e and a ?-l CFD model to air flow phenomena on various terrains. More recently, Choudhury (2011) used the COMSOL CFD package for modeling pollutant transport for an idealized open pit mine. Collingwood et al. (2012a, 2012b) used a two-dimensional model for fluid flow and contaminant transport at an Arctic open pit mine. The authors have also previously presented work on CFD modeling of an actual open pit mine at high latitude (Bandopadhyay et al. 2014, Raj et al. 2015a). However, the CFD work done by the above-cited researchers lacked model validation with field-measured data. Validation of a developed model is important in assessing the quality and accuracy of the predicted results. In general, experiments are done numerous times in controlled environments to assess the validity of collected data. There are two types of assessments used in CFD simulations: (1) verification and (2) validation. Model verification is checking the accuracy of the computer codes during the implementation phase of a real-world problem, within the specific limits of accuracy (Oberkampf and Trucano 2002). Since, the pollution transport model presented in this paper used the commercial ANSYS-FLUENT CFD package, verification is not needed as the program has been tested widely, and verified numerous times."

Jan 1, 2016

By Eoin Murphy, Stephen Beauchamp, Steven Cowell

"INTRODUCTION Electrification of the heavily trafficked Manchester to Preston route by Network Rail required the rehabilitation of the Victorian era Farnworth Tunnels to accommodate 21st century high speed trains. Network Rail, J. Murphy and Sons Ltd (JMS) and OTB Engineering Ltd (OTB) collaborated closely to complete these works in close proximity to heritage infrastructure whilst maintaining a rail service on the route. This significant challenge has been mastered by a combination of detailed investigation, complex modelling, robust design, extensive monitoring, ground treatment, secant piling, sprayed concrete, steel arches and segmental lining techniques. Investigation of the “Down” Tunnel found deformation and cracking of the lining and this was reconstructed during 11 weekend possessions. The “Up” Tunnel was filled with low strength concrete and a 9m diameter open face shield was used to construct an 8m diameter segmental lined tunnel during a 23 week blockade whilst traffic was maintained in the “Down” Tunnel. ELECTRIFICATION OF THE RAILWAY The Farnworth Tunnel project is part of the UK wide £1bn Railway Upgrade Plan to provide improvements throughout the rail network which includes the Manchester to Preston route. The project also supports the UK Government commitment to build a “Northern Powerhouse” by improving links that bind northern England together and which will help it release its full potential with a more balanced, healthier economy. The majority of the current UK rail network infrastructure resulted from the rapid growth of the railways in the mid to late 19th century which means that most of the existing tunnels are over 120 years old. Over the centuries the introduction of larger rolling stock has reduced the original clearances provided in tunnels. The electrification of a route requires that any over-line structures provide clearance for Overhead Line Equipment (OLE), new rolling stock and to meet modern standards. As part of Network Rail’s current electrification programme a further 36 tunnels have been identified on routes requiring electrification. Not of all these Victorian structures will require alterations to provide OLE clearance but the condition of the existing tunnels and modern fire / waterproofing requirements may ultimately dictate the need for rehabilitation."

Jan 1, 2016

By Yun Bai, Ang Chen, Xiangdong Hu, Yanfei Zhu, Gang Li

"It is well known that tunnelling involves a high degree of risk. Conventional risk management only evaluates risks and chooses mitigation measures before the start of a project. However, mitigation measures also introduce risks, which are ignored in the conventional risk control process when choosing different measures. The Multiphase Risk Management Method (MRMM) takes the risk of mitigation measures and dynamic risk control into consideration. This paper introduces this new method and provides a flow chart for better understanding. A case study of the MRMM is given based on Ningbo Metro Line 3, the first quasi rectangle shield tunnel in China. INTRODUCTION Tunnelling itself is generally complex and involves a high degree of uncertainty (Huang, 2006; Thompson and Thompson, 2006). In recent years, several metro tunnel projects in China have been involved in accidents (Wang, 2006; Gong and Zhang, 2012).As a result, Chinese tunnel engineers are paying more and more attention to risk management in tunnel projects (Xiao-lin and Ping et al., 2009; Zhong and Jia et al., 2014), and scholars around the world have put forward many management processes. Existing risk management mainly focuses on a particular stage of a tunneling project. Tunnel engineers or other project parties usually carry out risk assessment and set up schemes or choose mitigation measures before a project begins. The risk from this initial risk assessment may be defined as the initial risk (Bai and Dai et al., 2013). This kind of managing process has been widely used for its simplicity and comprehensibility. However, this static theory cannot properly reveal the dynamic character of the risk during tunnelling. In addition, to reduce the risk from unacceptable level to acceptable level also calls for optimum measures. Therefore, the multiphase risk management method was proposed (Bai and Dai et al., 2013). The purpose of this paper is to introduce and develop the MRMM, and to provide a brief flow chart to illustrate the risk management process based on it. Finally, an example of the first quasi rectangle shield tunnel in China in Ningbo Metro Line 3 is illustrated. It analyzes the initial and secondary risk and sets up a risk control system."

Jan 1, 2016

By John Reilly

"INTRODUCTION Successful management of megaprojects, meaning delivery within budget, on time and according to expectations, is a fundamental requirement. Many projects have been successful, some have not. This paper reviews megaprojects1, drawn from the author’s projects over the last 50 years, with “lessons-learned” and a summary of recommendations that, if implemented, would improve megaproject management and delivery. Characteristics of these projects are summarized – including outcomes related to key factors such as politics, management, organizational structure, contracting methods, cost estimates, risk and other elements. The projects include the Washington D.C. Metro, Boston Southwest Corridor, LA Metro, Toronto Rapid Transit Expansion Program, BART San Francisco, MARTA Atlanta, London Underground and the Washington State Highway megaprojects – including the SR520 Floating Bridge and the Alaskan Way tunnel. Other projects that illustrate successful, innovative management and contracting methods include the Madrid Metro (low-cost delivery), the Sydney Northside Storage tunnel (outturn cost, alliancing) and the Lake Mead tunnel (working in partnership, risk management). KEY ISSUES A characteristic of megaprojects is that their complexity increases exponentially with size (Reilly 2010, Galloway et al. 2012). These projects are very visible politically, have many stakeholders who must be satisfied and generally span many years and political election cycles. To be successful they must meet expectations, function efficiently, and be delivered under, at or close to budget and schedule. There is a widely-based perception that large, complex projects are always delivered late, over budget and with problems. Specific examples include projects such as Tren Urbano in Puerto Rico – $1.28 billion over initial budget (+133%), the Silver Line Transitway Project in Boston – $286 million over budget (+90%), the London Jubilee Line Transit Project – 2 years late and £1.4 billion (+67%) over budget, the Channel Tunnel Rail Project – £3.7 billion (+80%) over budget, Denmark’s Great Belt Link rail and road link (54% over budget), the 2003 Woodrow Wilson bridge tender in Virginia (72% over estimate) and Boston’s Central Artery Project – several billion (perhaps 100%) over what would have been a realistic initial budget and years late (Reilly 2001c, 2004a; Salvucci 2003)."

Jan 1, 2016

By Philip Antunes, A. E. (Tony) Reschke

"INTRODUCTION Tunnel Boring Machine (TBM) operations require the injection of material into the annular tail voids as the machine advances ahead of the segmental concrete lining. This annular gap is created because the cutting diameter of the TBM has to be larger than the outer diameter of the concrete segments of the tunnel lining. Fundamentally, the two basic types of annular grout are thick, concrete like mortars and thin, mobile, two-component grouts. While some European countries seem to still favor the concrete like mortars, from a global perspective it is now the two-component type grouts that dominate the industry. Two-component type grouts are comprised of an “A” component grout (typically cement, flyash, bentonite and a retarder/stabilizer) and a “B” component accelerator (sodium silicate or water glass as it is sometimes known). They are thus sometimes referred to as A/B type or bi-component grouts and were pioneered by the Japanese over 30 years ago. They offer a host of operational benefits over thick mortars, such as reduced settlement (Feddema et. al., 2001), effective penetration of the void space, with less energy, and reduced strain on the segmented linings (Robinson et. al., 2007). Two-component grouts are highly mobile and can be pumped many kilometers. The use of a retarder/stabilizer can also extend the shelf life of the “A” component grout for several days while the early strength of the accelerated grout stabilizes the ground and supports the segmental liner almost immediately. The batch plants that prepare the two-component grouts use one of two possible mixing methods for preparing the “A” component grout. The simplest plants use paddle type mixers and numerous tunnels worldwide have been successfully grouted using this technology. However, a superior type of mixer is available, namely the high shear colloidal mixer. Keller Colcrete successfully pioneered the development of the colloidal mixer back in 1937 and for over 75 years colloidal mixers have been internationally recognised as the most efficient method of mixing cement based grouts (Houlsby, 1990). These mixers are used in grout preparation for radioactive waste encapsulation, hydro dam grout curtains, soilcrete jet grouting, soil nailing, and numerous other geotechnical applications. In tunnelling, these mixers are also used for ground treatment, compensation grouting and for the preparation of bentonite lubrication for pipejacking. It has been only within the last decade however that these high-shear colloidal mixers have been adapted for use in the preparation of two-component grouts."

Jan 1, 2016