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By Erika Moonin, Jim Nickerson, Claudio Cimiotti, Roberto Bono

"In response to the severe drought on the Colorado River basin and in order to preserve existing water capacity to the Las Vegas Valley, the Southern Nevada Water Authority contracted a new deep-water intake (Intake No. 3) located in Lake Mead. The current project (Contract No. 070F-01-C1) includes 5 km (3 miles) of tunnel with very difficult geological conditions and a 200- m (650-ft) deep shaft and marine works. This paper will present the current status of the design-build contract being constructed by Vegas Tunnel Constructors and the challenges and problems faced and the innovative solutions developed to handle the difficult conditions encountered during tunneling with up to 15 bars of pressure.ProjectbackgroundThe Las Vegas Valley receives the majority of its water from Lake Mead, which is located approximately 30 km (20 miles) east of the Las Vegas, NV metropolitan area. Due to the severe drought that has hit the southwest region of the United States, the water level in Lake Mead has receded from its high water level of 372 m (1,221 ft) above mean sea level (amsl) to a low of 330 m (1,076 ft) amsl in June 2015. Should the lake level continue to fall, at elevation 320 m (1,050 ft) amsl, the current water intakes will not be able to draw enough water to meet the needs of the local area. The risk of losing water capacity has prompted the construction of a new deeper intake. Not only is the new Intake No. 3 situated at a lower elevation in the lake at 262 m (860 ft) amsl, the new Intake No. 3 is also located to draw better quality (Fig. 1).Project challengesThe project has had several difficult challenges to overcome:• The work consisted of a 1.2 kt (1,300 st) structure constructed on a barge and lowered 100 m (330 ft) into Lake Mead anchored with 9,200 m3 (12,200 cu yd) of tremie concrete.• The drill-and-blast starter tunnel was impacted by three inflow events, resulting in a one-year project delay.• One of the main challenges was selecting the tunnel boring machine (TBM) and excavating the tunnel with expected hydraulic head pressure of as much as 17 bar (16 bar was the highest pressure recorded during the drive), crossing faulted areas, low rock cover and the risk of tunnel instability due to direct connection with the lake.• Extensive pre-excavation grouting with a constant head pressure ranging from 12 bar to 15 bar.• Structural repair of the cutterhead in difficult hydrogeological conditions [water inflow of approx. 800 m3/hr (4,000 gpm)].• Complete repair of the cascade sealing system for the main bearing and two replacements of the pinion bearings.• The TBM approach to the intake structure."

Jan 1, 2015

By Steve Kral

The Underground Construction Association?s (UCA) 2014 North American Tunneling (NAT) conference is expected to attract about 1,000 tunneling and underground construction professionals. With the theme ?Mission Possible,? attendees from around the world will hear the latest in tunneling and underground construction technology in the two-and-a-half days of technical sessions. The meeting is scheduled for June 24-27 at the JW Marriott Los Angeles Live in Los Angeles, CA. In addition to the technical programming, the accompanying exhibit has attracted 143 exhibitors in 162 booths. And the conference will offer short courses and plenty of social activities that will provide attendees the opportunity to catch up with each other. In addition, a proceedings volume containing all of the 128 papers will be available. An impressive lineup of sponsors will help attendees enjoy the conference. They include Brierley Associates, Kiewit Infrastructure Group, Parsons, Skanska, Traylor Bros., MWH and HNTB.

By Gunnar Nord, Per-Anders Persson, Duri Prader

The paper gives a short resumé of the findings of the joint US - Swedish "Mechanical Boring (MB) or Drill and Blast Tunneling (DB) ? Workshop" in Stockholm December 1976. New developments and trends in both MB and DB techniques in Europe since 1976 are described, and information is given on some interesting new projects. Differences in contracting principles between the US and Europe lead to different practices for preinvestigations, design, excavation and arbitration and legal affairs. It is shown that this often leads to a higher cost in the US than in Europe for similar excavation jobs. A typical US tunnel job also has more men on the site than a similar job in Europe. This adds to the cost difference and is only partly balanced by a slightly higher rate of excavation in the US. A comparison is made between two quantitative methods of predicting MB penetration rates. These are in reasonable agreement. A probable future development in machine design is an increase in cutter load towards perhaps 25 tons per disc where the tunnel diameter is large enough to house the machine size dictated by the size of the very large electric motors required. Recent European developments in drill and blast technique include improved methods for cautious blasting, precision hydraulic drilling of small diameter holes, and non-electric interval blasting techniques. These developments still keep the drill and blast method ahead of mechanical boring costwise for tunnels in igneous rock whereas for most sedimentary materials mechanical boring has a lead, particularly for long tunnels.

Jan 1, 1979

By G. Vogt

Water is one of the most important ressources of our planet. Unlike many other natural resources, water cannot be substituted by anything and must therefore be handled with the utmost care. Depending on the region and the possible shortage of water, the importance of water increases even further. Water consumption is not the only factor. In the construction industry, water pollution from auxiliary and operating materials and processes as well as other contaminants and their resulting load on wastewater play an important role. The sources for wastewater on tunneling construction sites are various: Washing water, seepage water accumulating in construction pits, tunnel water, water used in the slurry circuit in fluid-assisted tunneling methods or water from concrete work and stone cutting all these waters are contaminated with a range of pollutants like solids, hydrocarbons, heavy metals, etc. These contaminants can be removed or treated/reduced with the help of specifically designed wastewater treatment plants (WTPs). After the treatment the cleaned water can be either, in best case, reused on the construction site itself or discharged into water utilities like the available sewer or river pin respecting their discharge requirements. Due to dwindling water resources globally, the continuously rising discharge limits and the ever more important aspect of sustainability the use of WTPs on tunneling construction site will be indispensable. In this paper, it will be presented how these systems are designed and work, what advantages they offer environmentally as well as financially and what to look out for when planning and implementing such a system onto jobsite.

Jun 23, 2024

By Priscilla P. Nelson

Many concepts concerning equipment selection, performance prediction, and evaluation of support requirements for tunnel construction in soil or hard rock tunnels cannot be extrapolated directly for application in soft rock (compressive strength between 1.0 and 35.0 MPa). Case histories for small diameter (less than 3.5 m) tunnels in Austin, Texas, are analyzed to gain insight into particular problems encountered during tunnel excavation in weak sedimentary rock, and the performance of different excavation systems are compared.

Jan 1, 1987

By Diana Diaz, Rakshith Shetty, Vitaly Proschenko, Mike Mooney

Cohesive clay soil poses a significant risk to earth pressure balance tunnel boring machines (EPBM) due to unstable face pressure, clogging potential, high cutterhead torque, poor muck flow, low advance rate, etc. This paper details the performance measures desired when EPBM tunneling in clay soil, and the scientifically-supported conditioning methods to transform in-situ clay to a muck with such characteristics, giving particular attention to ground conditions. The paper then examines TBM data from multiple clay soil projects in the context of these performance measures to demonstrate the influence of cohesive soil conditioning on EPBM performance.

Jun 13, 2023

By Steve Karl, Rock Jenkins

Continuing its objective of sharing new ideas, methods, theory, and engineering developments, more than 550 members of the underground fraternity gathered in New York City for the 1985 Rapid Excavation and Tunneling Conference (RETC). Since the first meeting in 1972, RETC’S aim has been to lay a foundation of tunneling experience on which the industry could expand and develop over the years. The RETC is jointly sponsored by the American Institute of Mining, Metallurgical, and Petroleum Engineers (AIME), the American Society of Civil Engineers, in cooperation with the Canadian Institute of Mining and Metallurgy, and the Engineering Institute of Canada. The 17 sessions included 72 papers that explored up-to-date practices in the mining and civil engineering fields. Session topics ranged from geotechnical and seismic design, through design, construction, and support of underground openings, to ground water control in shafts and mine openings. Case histories of tunnel boring machines and large diameter tunnel and underground openings were also reviewed. All the papers presented at the three-day conference are valuable additions to improving the state of rapid excavation. A few sessions, however, are particularly noteworthy as they are geared to the mining industry. The two volume proceedings of the entire conference are available from SME. (See ad on page 1003).

Jan 7, 1985

The Earth?s population is approaching 6.6 billion people. More than half live in urban areas. And, as those figures continue to grow, the need to make wise use of the world?s natural resources as well as its living space will also grow. Thus, the concept of sustainable development ? meeting the needs of the current generation while preserving resources for future generations. The use of underground space is only one part of the sustainable development concept. But it is an important one. Tunnels and underground space are environmentally friendly and contribute significantly to sustainable development. But it takes years to plan and build tunnels and other underground infrastructure. And the demand for infrastructure in the world?s mega cities has grown significantly. In December, about 100 people representing several developed and developing nations spent a day at the United Nations (UN) in New York City discussing the future of underground space development throughout the world. The meeting was put on by the UN?s Department of Economic and Social Affairs and the International Tunnelling and Underground Space Association (ITA). The conference was titled ?The Use of Underground Space as an Unexpected Solution for Promoting Sustainable Development.? Its aim was to promote practical solutions to the use of underground space and tunnels as feasible alternatives to promote sustainable development throughout the world. A panel of speakers from government, academia, the UN and the ITA stressed that development is not sustainable without infrastructure. And, as the world?s population grows, there is now an urgent requirement to efficiently plan for the use of underground space to preserve it for the future benefit of mankind. The benefits of the use of underground space are many, they said. Among them: ? Tunnels channel clean water in and waste water out. This promotes health and sustainability worldwide, particularly in developing countries. ? The use of tunnels and underground space helps conserve energy and increases its efficient use ? the use of tunnels cuts commuting time and so saves energy. ? Tunnels, microtunnels and other underground structures promote the more efficient use of space in large cities ? the bulk storage of water, fuel and other goods. ? Underground structures are subject to less stress than surface structures, making them safe havens for natural and man-made hazards, including earthquakes. And, because underground structures are more durable, lifecycle costs are less than surface structures. ? Underground structures promote the multiple use of available land. Land owner-ship at several layers increases land use and provides more usable space. Han Admiraal is director of the Center for Underground Construction in the Netherlands. He said that urban planners need a new vision concerning the use of underground space. Going underground protects historical and archaeological surface facilities, he said. Underground space use can also protect populations located in adverse climates. And sensitive environmental areas on the surface can also be protected from development. In addition to the transportation of people, freight and water, underground development can also store water, as well as provide storage for waste, hazardous materials, carbon dioxide and geothermal energy. The upshot of this new awareness and vision for under-ground space is that its use should be considered before surface development, Admiraal said. And planners and developers are placing more emphasis on underground space development as part of their overall development plans for urban areas. That was not always the case, he said. In the past, underground space was not considered until after the surface space had run out, he said.

Jan 1, 2008

By Nik Sokol, Mike Jaeger, Leo C. Weiman-Benitez

Silicon Valley Clean Water signed a progressive-design-build (PDB) contract with Barnard Bessac Joint Venture (BBJV) to design and construct the Gravity Pipeline tunnel in Redwood City, CA. Owner and Design-Builder teamed with designer Arup to provide a final product: 3.3 miles of 182 in. O.D. precast concrete segmentally lined tunnel with 10 ft. and 11 ft. I.D. Fiberglass Reinforced Polymer Mortar (FRPM) carrier pipe, complete with two FRPM Drop Structures. BBJV and Arup collaborated with SVCW to evaluate alternative design concepts, negotiate an agreeable price and reduce contingencies through a transparent estimating process, and deliver the project ahead of schedule.

Jun 13, 2023

By H. J. Handewith

"After having performed qualitative and quantitative tests on nearly 550 rock specimens from tunnel projects throughout the world and comparing the results with actual boring in eight distinctly different rock types which varied in compressive strength from 12,000 to over 34,000 psi, it has been concluded that any rock -andesite, granite and even taconite -can be machine-bored. The question is -can it be bored economically? The intent of this paper is to delineate the investigative needs to accurately and reliably answer this question. A piece of NX core in the hand represents less than 50 per cent of the worthwhile geologic information that could have been obtained from a given core hole. A thorough site investigation by competent personnel can gene-rally foretell to what extent, if any, varying geologic conditions will hinder machine progress.A laboratory testing technique has been developed that has been correlated well (80 to 120 per cent) with actual boring results. This technique will be discussed in detail. Rock cutter life is a function of the penetration rate and the forces required to sustain that rate. Cutters are now, and will be for .some time to come, the single, most expensive consumable item involved in continuous tunneling in hard rock. It is by strict attention to predicting these rates and forces that tunneling costs can be optimized."

Jan 1, 1970

By Alena Conrads, Markus König, Markus Scheffer, Markus Thewes, Hannah Mattern

"INTRODUCTION In recent years, the development of tunnel boring machines has revolutionized the tunneling industry. The general structure of a tunnel boring machine (TBM) can be described as a multi-component system. To achieve high performance rates, machine elements have to perform reliably. Performance losses and interruptions of the construction process should be prevented or at least, reduced to a minimum. In order to achieve high advancing rates, cutting tools must be in good condition at any time. Furthermore, failure of individual tools might result in increased and faster wear of remaining structural components. For this reason, maintaining and replacing cutting tools is crucial to prevent project delays due to insufficient boring performance. Precise prognoses concerning the prevailing geology are infeasible and thus, efficient scheduling of maintenance actions is challenging. The intention of this work is to analyze different approaches of TBM maintenance in soft ground. Different strategies are analyzed by the use of a simulation approach. Cutting tool condition is regarded as performance limiting factor. The maximum operation time of the cutting tools is determined using the “Soil Abrasivity Index”. A case study serves to show the effects of different maintenance strategies on total project duration. SCHEDULING OF MAINTENANCE ACTIONS Scheduling maintenance actions of single and multi-component systems concerns numerous fields of industrial production. Concentrating on mechanized tunneling in soft ground, cutting tool maintenance represents the most common reason for intermission of advance (Köppl 2014). In literature, time-based and condition-based maintaining techniques are widely discussed. The following section outlines the principles of time- and condition-based policies. Furthermore, examples for their applications in recent research are given. Time-Based Maintenance In general, the time-based maintenance approach assumes that the failure behavior of the system components is predictable. Maintenance actions are scheduled according to predefined intervals (e.g., hours, days, weeks). A detailed analysis of preventive repair times or interval forms the basis for maintenance decisions. For this approach, an adequate quantity and quality of data is fundamental. Numerous studies deal with the analysis of time-based maintenance for production equipment. In fields of mechanized tunneling, unplanned machine downtimes restrict the applicability of time-based maintenance approaches. Thus, this paper mainly focuses on condition-based maintenance."

Jan 1, 2016

By David R. Wayman

This paper summarizes environmental compliance and related issues associated with underground construction and tunneling operations, whether new work or rehabilitation. Underground construction and tunneling operations have (in most cases) both an underground and surface component. Since many of the major tunneling projects occur in urban areas, often is areas inhabited for several decades or centuries, environmental problems may already exist in a project area, though that may not yet have been formally recognized. Large projects often attract more than their fair share of regulator attention. This paper addresses the issues with the greatest potential to be encountered by underground constructors, with the emphasis on minimizing contractor liabilities, both in the short- and long-term. Minimizing contractor liability begins with understanding bid documents, contract provisions and necessary means of protection, and carries through project execution by responsible control of hazardous materials, avoidance of media contamination, proper waste disposition, as well as compliance with other environmental requirements.

Jan 1, 1999

By Kenneth W. Torpey, James G. Ball, Richard F. Flanagan, David S. McAllister

INTRODUCTION Under a Federal grant by the Urban Mass Transit Administration (UMTA) (80%), and sponsored by the State of New York (200), Niagara Frontier Transportation Authority is constructing a 10.3 km (6.4 mile) light rail rapid transit system in Buffalo, New York. The $450 million project, which began construction in the Spring of 1979, is unique in rail transit alignment designs in the U.S.A. and the first predominantly underground light rail system in North America. The Buffalo project is unique in that the first phase of the expandable system follows the alignment of Main Street and is on the surface in a proposed 1.6 km (1.0 mile) pedestrian mall in the downtown business district. The alignment then progresses northward into a cut-and-cover portal and standard double-box configuration for 2.74 km (1.7 miles) at a depth of 9.1-10.7 m (30-35 ft) and subsequently drops into bedrock at depths of 18.3-27.4 m (60 to 90 ft). The 5.63 km (3.5 mile) rock tunnel section consists of two single tunnels 4.88 m (16.0 ft) nominal finished diam. and includes five stations. The rock tunnel line section was divided into a north and south contract of 2 316 m (7,600 ft) and 3 243 m (10,640 ft), respectively. Due to the existing surface facilities and the future station locations, the line tunnel contracts differed considerably in their shaft access

Jan 1, 1981

Later this month (June 24-27) in San Francisco, the Society of Mining Engineers of AIME, together with the American Society of Civil Engineers, the Canadian Institute of Mining & Metallurgy and the Engineering Institute of Canada, is sponsoring the second biannual Rapid Excavation and Tunneling Conference. The dominant theme of the Conference is the practical application of techniques and research relating to underground rapid excavation and tunneling. In the following pages, ME gives highlights of many of the 24 technical sessions and some of the papers being presented. The full proceedings of the Conference will be published by SME-AIME later this year.

Jan 6, 1974

By Peter J. Tarkoy, Terence G. McCusker

INTRODUCTION The discovery of oil and gas reserves in the North American Arctic has led to substantial thought being given to their development. Systems adequate for exploration are not always, or even often, suitable for permanent installations. Combinations of offshore pipeline, drilling ships, platforms, sub-sea systems, sand islands and -ice island bases have been proposed. However, conditions in the Arctic are such that these methods may be difficult or impossible to implement. Problems exist with (1) the freezing of the Arctic Ocean surface for 9 - 10 months per year, (2) the movement of sea ice, (3) scouring of bottom sediments by ice islands and icebergs to great depths below the ocean bottom and (4) deep water channels. Any method which can avoid the problems associated with surface construction in these very adverse conditions merits detailed examination. One of the proposed solutions is to tunnel from a convenient or available access point to a point within the field, construct a chamber large enough to accommodate the drilling equipment and drill the development wells in a protected environment. Service and delivery lines would use the access tunnel and further tunnels and chambers would be constructed in a radiating pattern to develop the whole field. In order to determine the feasibility of underground construction in the North American Arctic, it is first necessary to understand the geologic and environmental factors which would affect such construction, to be knowledgeable concerning the problems and then to consider the techniques appropriate to the conditions which will be encountered, bearing in mind the need to minimize both con-

Jan 1, 1976

By K. E. Wood, K. J. DiRocco, L. A. Becker

The Russia Wharf segment of the Silver Line Phase II Project for the MBTA incorporated ground freezing and underpinning during New Austrian Tunneling Method(NATM) tunneling through timber pile foundations, urban fill, and abandoned wharf structures beneath two historic 7-story buildings with steel frames and masonry facades. During construction, the project team implemented an extensive program to monitor, evaluate, and mitigate the ground and building movements caused by the various construction activities. Mitigation included freeze cycling and building raising/lowering to compensate for ground movements and safely maintain the serviceability and occupancy of the buildings. In this paper, we present the history of the freeze, tunnel construction, and thaw-related movements that occurred and the building response that we observed.

Jan 1, 2005

By Thomas Adair

Moderator-Thomas Adair is now a tunnel consultant with Perini Corp., Spring Lake, N.J. He has had 40 years experience in tunnel and shaft-sinking work in both soft and hard rock, as well as subaqueous rock. He has used moles in various locations and has traveled around the world studying the problems. SOME BRIEF COMMENTS ON "MOLES" by Thomas Adair We of the Perini Corp. have been, over the past 15 years, in the forefront of the battle to develop the mechanized miner. We have contributed much to pioneer, develop, and promote the use of the mining machine. Our money and talent have not been spared in this effort. However, we are sorry to say that as of the present time (1968), at least from the economic stand- point, this effort has not been very rewarding. But, I must say to those who are presently involved in the work of building mining machines, do not be discouraged. There is money in it. We of Perini Corp. know because we put it in there. It has been estimated that during the next 15 years, some $20 billion will be spent on underground excavation; more than 13 thousand miles of sub- surface tunnels will be excavated throughout the nation. An aggressive, properly structured research and development effort would produce, within the next five or ten years, a better excavation technology and improved boring system capable of reducing present costs drastically, with a resultant great saving. The time for this effort is now, but where the enabling money for this effort will come from, I have no idea. Machine builders should be encouraged to design and develop a shield- type boring machine capable of continuous mining through varying types of ground or rock by incorporating the possibility of making minor modifications such as change of bit type, power package, etc. Such a machine could

Jan 1, 1970

By Klaus Rieker

The main train station of Leipzig in Germany is currently being upgraded from a head station to a partially thru station. In order to achieve this, significant ground improvements are necessary. Soil freezing for example is used to create the excavation box retaining walls. The freezing works will be carried out from two tunnels with an inner diameter of 2.4 m (~ 8ft). The tunnels were constructed by the pipe jacking method. The cutter head of the machine was equipped with discs and scrapers. Driving and excavation was carried out using a bentonite supported face. Due to the small arrival shafts, the machine had to be lifted out in components. The essential limitation of settlements during the drives was achieved even better than expected.

Jan 1, 2008

By James J. Kabat, James A. McDonald

Impregilo/SA Healy JV recently completed this Project using the first slurry shield TBM’s in the United States. The Project used two TBM’s to mine 18,000 feet in sands, gravels, and silty alluvial materials under the Willamette River and downtown Portland, Oregon. This paper discusses alignment and geological conditions, equipment selection and plant setup, and tunnel excavation means and methods, parameters, and results. Extensive hyperbaric operations were required and will also be discussed.

Jan 1, 2007

By Christoph Schulte-Schrepping, Bou-Young Youn, Rolf Breitenbücher

"The main requirements of two-component grouts are a high workability and sufficient stability against sedimentation with a retention time of more than 72 hours, as well as a rapid strength development im-mediately after grouting. Component A usually consists of OPC, water, bentonite, and retarding agent. Component B, a liquid accelerator, is added to Component A during grouting at the end of the shield tail. Current investigations on different compositions of Component A showed a high workability lasting for at least 72 hours. The workability could be extended with increasing amount of the retarding agent to a certain degree. An increase of the bentonite content improved the stability of the mix, but had a negative impact on the flowability respectively the workability of Component A. High compressive strengths could be rather achieved by an adapted mixing ratio of Component A and B than by increasing the amount of the accelerator. Thereby, the interactions and compatibility of the selected constituents play an essential role. INTRODUCTION In mechanized tunneling with segment linings, the annular gap between segment ring and soil must be filled instantaneously with an adequate grouting mortar. The main functions of the annular gap grouting are to stabilize the tunnel lining and to minimize settlements of the ground surface at the same time. Thereby, two contradictory requirements are demanded on annular gap grouts: On the one hand a high workability and sufficient stability against sedimentation, on the other hand a rapid strength develop-ment immediately after grouting. Besides single-component grouts, which achieve the necessary stiffen-ing by dewatering into the surrounding soil, two-component grouts are used, especially in cohesive soils with a very low permeability. Basically, annular gap grouts are almost exclusively defined on empirical basis. Fundamental studies about the constituents and composition of the grout as well as the related achievable properties are still missing so far. Therefore, it is necessary to investigate the material-specific correlations regarding the relevant parameters of annular gap grouts – workability and flowability, stability of the mix as well as strength development – in comprehensive experiments. Based on the knowledge gained from the investigations, it should also be possible, to perform the grouting material according to a real design concept and thus, to ensure an adequate grouting in prac-tice considering the geological and hydro-geological conditions."

Jan 1, 2016