Tunnel Engineering Handbook

Frontmatter

1. An Introduction to Tunnel Engineering

Abstract

A tunnel is much more than just a tunnel. It serves any of myriad functions—highway, railroad, or rapid transit artery; pedestrian passageway; fresh water conveyance, cooling water supply, wastewater collector or transport; hydropower generator; or utility corridor. Tunnels are constructed by cut- and-cover methods; in long, prefabricated sections sunk in place as in immersed tubes; in short prefabricated sections pushed into place from jacking pits; by drilling and blasting; by mechanized means such as tunnel boring machines or continuous miners (roadheaders), with the aid of a protective shield in free or compressed air; and they will eventually be constructed in ways now existing only in our imaginations. In cross section it takes one of several shapes—circular, multicurve, horseshoe, cathedral arch, arched, or flat-roofed, and with clear spans of from a few feet to more than 50 ft and, in cavern form, much wider. Its length can vary from less than 100 ft to more than 30 miles. A tunnel can be lo- cated in any of a variety of places—under mountains, cities, rivers, lakes, sea estuaries, straits, or bays.

Elwyn H. King, Thomas R. Kuesel

2. Tunnel Layout

Abstract

This chapter covers considerations of internal clearances and overall alignment that are common to all transportation tunnels, including highway, railway, and rapid transit. Water tunnels are governed by different considerations, discussed in Chapter 15. Also covered here are limitations on the tunnel layout imposed by operating requirements and by factors inherent in certain construction methods. Finally, alternative layout concepts for underwater tunnels, which generally admit a greater variety of approaches than land tunnels, are discussed.

Elwyn H. King, Thomas R. Kuesel

3. Tunnel Surveys and Alignment Control

Abstract

Sputnik 1, launched October 4, 1957, heralded a revolution in technology that has continued to expand at an ever-increasing rate. The development of electronic computation and miniaturization of computer components, together with advances in communication and satellite technology, have significantly affected the surveyor, providing instruments and techniques that greatly enhance the accuracy and production rate of surveys for all aspects of planning, design, and construction. In the recent past, requirements for field and office work often had to be tempered by the cost and time needed to accomplish the survey and prepare computations and maps, because of the amount of labor needed to accomplish the work.

Peter K. Frobenius, William S. Robinson

4. Geotechnical Investigations

Abstract

Geology plays a dominant role in many major decisions made in designing and constructing a tunnel, from determining its feasibility and cost to assessing its performance. In tunnels, unlike other structures, the ground acts not only as the loading mechanism, but as the primary supporting medium as well. When the excavation is made, the strength of the ground keeps the hole open until supports are installed. Even after supports are in place, the ground provides a substantial percentage of the load-carrying capacity. Thus, for the tunnel designer and builder, the rock or soil surrounding a tunnel is a construction material. Its engineering characteristics are as important as those of the concrete or steel used in other aspects of the work.

Harvey W. Parker

5. Tunnel Stabilization and Lining

Abstract

This chapter covers the behavior of tunnels during excavation, and how this behavior may be modified by installation of a variety of reinforcing or supporting systems. Stabilization designates systems installed before, during, or immediately after excavation to provide initial support and to permit safe, rapid, and economical excavation. Lining designates systems installed either shortly or considerably after excavation to provide permanent support and durable, maintainable long-term finishes. The type of system chosen depends primarily on the ground conditions and on the end use of the tunnel. Frequently, stabilization and lining are provided in two separate operations; this is called a “two-pass” system. In some situations, a “one-pass” system will combine the functions of stabilization and lining.

Thomas R. Kuesel

6. Soft Ground Tunneling

Abstract

As the population of urban areas increases, so will the congestion at the earth’s surface. To provide the services (e.g., transportation, water and wastewater, utilities) required by the populace, more and more of those services must be provided by going underground, simply because economical space to provide those services does not exist at the surface. Since tunneling is less disruptive and destructive than cut and cover and since tunneling depth in most large cities lies within the soft ground zone, it is clear that the need for soft ground tunnels will increase. This chapter covers the major considerations that influence the design and construction of soft ground tunnels, which are defined as tunnels that could be excavated using hand tools and methods, although they seldom are in today’s mechanized world.

James E. Monsees

7. Rock Tunnels

Abstract

As late as World War II and for a number of years thereafter, rock tunnels were “designed” by assigning the responsibility (and all risks) to the contractor for excavating and stabilizing the ground and then constructing a concrete lining of contractual dimension and detail. Lining thickness was based on judgment and prior experience. This frequently boiled down to roughly an inch of thickness per foot of span, with some adjustment for quality of rock anticipated. The lining was conceived of as a conventional freestanding arch, such as a bridge arch, carrying a uniform load of (dead) rock of arbitrary thickness, or alternatively, a half-span loading of similar thickness in order to “quantify” moments by which to design the reinforcing steel.

Elwyn H. King

8. Tunneling in Difficult Ground

Abstract

In this chapter, the emphasis is placed on creating and maintaining stable openings in ground that actively resists such efforts. As adjuncts to tunneling, mention is made of the problems of creating permanent portals in predetermined locations and some of the stability problems encountered in cavern excavation.

Terrence G. McCusker

9. Shafts

Abstract

There are generally two modes of access to tunnel construction: through a portal providing direct access at the surface or through a shaft providing vertical access to the level of tunnel operations. Since urban land is valuable and interference with existing services must be minimized, most tunnels built through urban areas require shafts to reach the working area and to provide for removal of tunnel muck.

Robert J. Jenny

10. Deep Shafts

Abstract

Very deep shafts have traditionally been associated with the gold mining industry in South Africa, where depths of 6,000 to 8,000 ft are common. In good, hard rock with dry conditions, shafts with circular concrete linings of 25 to 30 ft internal diameter have been conventionally sunk and lined at rates of up to 1,250 ft in a month (e.g., Buffelsfontein Eastern Twin Shaft, 1962). In contrast to mine shafts worldwide, where 2,500 ft depths have been commonplace for over a century, the very deepest shafts for most civil engineering projects rarely exceed 2,000 ft depth. Applications include ventilation shafts more than 2,000 ft deep for long transportation tunnels through high mountain locations such as the trans-Alpine tunnels connecting population centers in Switzerland, Austria, and Italy, and high-pressure penstock shafts of 2,000 to 3,000 ft deep for hydroelectric pumped storage projects.

Maurice Grieves

11. Tunnel Boring Machines

Abstract

Tunnel boring machines (TBMs) are used to excavate tunnels in virtually all types of ground and under widely different physical conditions. This chapter covers hard and soft rock TBMs with full-face rotating heads and their development from soft ground shields. Roadheaders (boom headers) are also discussed here because of their growing role in the softer rock tunnels and caverns. The innovative Ranging Mobile Miner, which combines some of the advantages of the roadheader and the TBM and can be used in harder rocks, is also covered.

Harry Sutcliffe

12. Shotcrete

Abstract

Shotcrete is not just “pneumatically applied concrete.” Although the basic materials (cement, aggregates, water) are the same and meet the same ASTM standards, additives (e.g., accelerators, microsilica, and steel fibers) change its character to make shotcrete unique and usable in quite a different fashion than concrete.

Elwyn H. King

13. Materials Handling and Construction Plant

Abstract

Materials handling is the key element in the tunneling process. To achieve their designed productivity, virtually all tunneling activities depend upon materials handling systems. Likewise, the facilities required to support the tunneling operation are largely oriented toward keeping the materials handling systems operating efficiently and at their planned rates of production. This requires systems for communication, power supply, and environmental control as well as facilities for storage, equipment maintenance, personnel needs, and administrative functions.

A. A. Mathews

14. Immersed Tube Tunnels

Abstract

Immersed tube tunnels are composed of prefabricated sections placed in trenches that have been dredged in river or sea bottoms. The sections are usually constructed at some distance from the tunnel location and made watertight with temporary bulkheads. They are then floated into position over the trench, lowered into place, and joined together underwater. The temporary bulkheads are removed, and the trench is backfilled with earth to protect the tubes. Immersed tubeshave been widely used for highway and rail crossings of soft-bottomed, shallow estuaries and tidal rivers or canals in which trenches may be excavated with floating equipment.

Ahmet Gursoy

15. Water Conveyance Tunnels

Abstract

Water conveyance tunnels require special considerations regarding friction losses, drop shafts for vertical conveyance, air removal, control of infiltration and exfiltration, tunnel linings, lake taps and connections to live tunnels, and maintenance.

David E. Westfall

16. Small-Diameter Tunnels

Abstract

Conventional tunnels are driven by workers excavating, supporting, and advancing the tunnel at its face. As the tunnel diameter decreases, work becomes more difficult. Thereis less room for personnel. Efficiency and advance rates decrease. It becomes increasingly difficult to erect the tunnel lining system from within the tunnel. At diameters of 60 to 18 in., it becomes more efficient to push the lining into place from a shaft or portal. This lining is a string of pipe sections. This method of tunnel construction, commonly referred to as pipe jacking, was introduced in the United States during the 1890s. Pipe jacking is commonly used at highway and railroad crossings to install conduits or sewers through soft ground instead of trenching. References

David E. Westfall, Glenn M. Boyce

17. Cut-and-Cover Tunnel Structures

Abstract

Shallow-depth tunnels, such as large sewer tunnels, vehicular tunnels, and rapid transit tunnels, are frequently designed as structures to be constructed using the cut-and-cover method. Tunnel construction is characterized as “cut-and-cover” construction when the tunnel structure is constructed in a braced, trench-type excavation (“cut”) and is subsequently backfilled (“covered”). For depths up to 35–45 ft this method is often cheaper and more practical than underground tunneling, and depths of 60 ft or more are quite common for rapid transit cuts. This chapter discusses the design and construction of the larger cast-in-place concrete structures used as sewer tunnels or transportation tunnels for pedestrian, vehicular, or rapid transit traffic. The tunnel is typically designed as a box-shaped frame, and due to the limited space available in urban areas, it is usually constructed within a braced excavation. Where adequate space is available, such as in open areas beyond urban development, it is often more economical to use open-cut construction.

James L. Wilton

18. Safety Provisions

Abstract

At one time, tunnel accidents claimed one life for every half mile of tunnel constructed. Increased concern over construction safety has led to improvements in the miner’s working conditions, with a subsequent reduction in the frequency of deaths and disabling accidents. However, based on 1986 OSHA statistics, lost-time accidents still occur at more than twice the frequency for underground workers compared with other construction workers, and three times the rate for manufacturing workers. Approximately the same adverse ratio applies to fatalities. Obviously, there is a need for more improvements in safety for underground workers.

Robert J. Jenny

19. Fire Life Safety

Abstract

Major tunnel fires have been rare occurrences. However, the potential for entrapment and injury of large numbers of people who routinely use highway tunnels, underground mass transportation facilities, or mainline railroad tunnels warrants special considerations.

Norman H. Danziger

20. Tunnel Ventilation

Abstract

Whereas tunnels themselves date back to early civilizations, the ventilation of tunnels has taken on greater significance only within the past 100 years, as increasing quantities of combustion products and heat have become more trouble some.

Arthur G. Bendelius

21. Tunnel Lighting

Abstract

The maintenance of traffic volume at design roadway speeds through a tunnel on a bright sunlit day depends on the ability of the motorist to see the interior of the tunnel and objects on the roadway for a safe stopping distance. The geographic location, orientation, and portal surroundings influence the ability of the human eye to adapt from the bright ambient roadway to the “black hole” of the tunnel interior. The lighting of the tunnel interior to eliminate and or diminish the effect of the black hole is achieved through varied lighting concepts. The most prominent lighting concepts employed are the symmetrical and the asymmetrical, of which there are two types: the counter beam and line-of-sight. Linear or point source luminaires or a combination of types of sources are employed to provide for specific illumination requirements for unidirectional or bidirectional traffic tunnels as appropriate to the system.

Peter A. Mowczan

22. Power Supply and Distribution

Abstract

Power supply and distribution systems for tunnels are similar to those of a high-quality industrial facility, where power must be distributed to the associated equipment and systems with a high degree of safety, reliability, voltage quality, and maintainability. Basic requirements of such systems are outlined in various publications, including the IEEE Red Book (IEEE, 1986a).

Elies Elvove

23. Water Supply and Drainage Systems

Abstract

Most tunnels will require systems to provide water to the tunnel and remove wastewater from the tunnel. A water supply system is required primarily for fire protection and possibly for wall-washing operations. A drainage system is necessary to collect, treat, and discharge the wastewater resulting from fire-fighting operations, washing operations, and leakage.

Arthur G. Bendelius

24. Surveillance and Control Systems for Highway Tunnels

Abstract

Unlike open highways, tunnels require special attention to maintain safety under normal and abnormal traffic conditions. Most modern tunnels, including their approach roads, require a centralized control system to meet these goals. Although not all tunnels require the same attention or installed features, they all have the following general features. [Note: The dimensions shown in this chapter are indicative guidelines. All English unit equivalents are soft (rounded) conversions of metric.]

Richard J. Naish

25. Tunnel Finish

Abstract

The elements or materials that constitute the exposed surfaces of a tunnel interior can be described as the finish of a tunnel. In tunnel work, the same term refers to elements installed after completion of the structural lining that constitute an integral part of the complete tunnel interior, often in a separate “finish” contract. Tunnel finish work can include wall and ceiling finish materials and support systems; tunnel roadway pavement, barrier curbs, sidewalks/safety walks, and railings; utility niche frames and doors, doors and frames for cross-passageway utility closets, used increasingly in lieu of sidewall niches; and police booths or sidewalk patrol cars. All can be considered finish work, and are discussed in this chapter.

Stanley Lorch

26. Service Buildings and Ancillary Spaces

Abstract

The number, type, and specifics of tunnel ancillary facilities and service buildings depend on the functional requirements of each tunnel. Broadly speaking, ventilation equipment, electrical switchgear, and other mechanical and electrical equipment required for the operation of a roadway tunnel are housed in one or more below- or above-grade buildings. There must be space to house and maintain service vehicles and emergency trucks, shops for electrical and mechanical repairs, and adequate storage for the material and equipment needed to operate and maintain the tunnel and related roadways. Traffic control and surveillance, communications and equipment monitoring functions must be accommodated,and facilities for operating personnel have to be provided. In addition, facilities for the administrative operation of the tunnel must be provided, either as part of a broader district operational facility or as stand-alone quarters.

Stanley Lorch, Hanan Kivett

27. Tunnel Rehabilitation

Abstract

Over the last few years, the concern for infrastructure has created a new interest in the rehabilitation of existing tunnel facilities. Many of the tunnels in the United States and abroad were constructed prior to World War II and are approaching their design-life expectations. However, due to the high cost of replacing these facilities, many tunnel systems are being rehabilitated to extend their useful lives well into the next century.

Henry A. Russell

28. Tunnel Construction Contracting

Abstract

A whole separate book (or several) could be written about tunnel construction contracting. The purpose of this brief chapter is to explain why tunnel construction is markedly different from aboveground construction, and why and how the philosophic basis for modern tunnel construction contracting has evolved.

Thomas R. Kuesel