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By Joseph P. Sobanski, Michael P. Bruen

The North Branch tunnel segment of the Tunnel and Reservoir Plan Mainstream System consists of 14,075 m (45,885 ft) of 9.2 m (30.2 ft) finished diameter and985 m (3,232 ft) of 2.5 m (8.25 ft) finished diameter concrete lined rock tunnels. The TBM mining and concrete lining methods used in completing this $166million project differed from “typical” TARP construction methods in that a two-stage concrete lining was placed and the lining was initially placed concurrently with TBM mining as a two pass system in the same tunnel segment. For the main tunnel (9.85 m diameter), TBM mining averaged 24 m/day (79 ft/day), excluding downtime associated with two main bearing changes, and the concrete lining placement, averaged 117 m/day (380 ft/day) and 53 m/day (174 ft/day) for the invert and arch segments, respectively.

Jan 1, 1999

By Odd E. Hanssen

In April 1982, the contracting Companies, ABV of Sweden and Hoyer-Ellefsen of Norway forming the Consorcio Escandinavo Agoyan, signed the contract for the construction of the civil works of the Agoyan Hydroelectric Project, located in Ecuador, South America. The project is located in the Andes mountain region of Ecuador - one of the smaller countries in this part of the world, located on the Pacific Coast. The contract was signed with the Instituto Ecuatoriano de Electrificación (INECEL), a public institution in charge of the development of all major energy producing projects in Ecuador, for a value of approximately US$ 120,000,000. The contract's main elements are - Concrete gravity dam with a total volume of approximately 210,000 cu m. (60 m wide x 45 m maximum height, 320 m crest). - 2,400 m of headrace tunnel, interior diameter of finished lining 6 m of which 450 m is in-situ tunnel formed in a trench. - Pressure shafts, 132 m long, the lowest meters with sheet lining, the rest with concrete lining. - Powerhouse cavern with an excavated volume of approximately 25,000 c m in which two turbines of 78 MW each will be installed. - Two 140 m tailrace tunnels with a finished diameter (concrete

Jan 1, 1985

By Wolfgang Gütter

India is targeting to boost its electrical capacity from 100 GW to 200 GW within the next 10 years. The National Hydroelectric Power Corporation (NHPC) has decided in2001 to take execution of the 800 MW Stage-II of the prestigious 2,051 MW Parbatihydrol electric project in Kulu district of the northern province Himachal Pradesh. Two parallel 30° inclined underground pressure shafts of 1.542m in length each will be excavated in different geological formations and lined with hexagonal concrete segments by a hard rock double shield TBM. That kind of heading will be a novelty to India and an innovative method for inclined pressure shafts. The 4.88m Mitsubishi DSTBM will be assembled underground on a swivelling steel platform especially designed for the launching as well as for the acceptance of the TBM in the upper cavern of each shaft. The hexagonal segmental lining system causes a significant higher job safety than an open TBM with conventional support. Each ring consists of four honeycomb segments with 20 cm thickness. After finalisation of the excavation a steel liner will be installed and concreted. The Joint Venture Jäger-Seli will perform the two pressure shafts as a sub-contractor for the Indian company Gammon India Ltd.

Jan 1, 2005

By Brian Fulcher

The Arrowhead Tunnels Project represents the final portion of a 70 km (44-mile) long water conveyance facility that will bring up to 28 m3/sec (1,000 ft 3/sec) of water into Southern California. The 13 km (8-mile) tunnelling project is well underway and consists of two, 5.8 m (19-ft) diameter TBM bores through extremely variable geological conditions. An extensive and essential pre-excavation drilling and grouting program was performed in all reaches of the Arrowhead Tunnels Project, located north of San Bernardino, CA. This program supported the advance of two hybrid hard rock TBMs though extremely challenging ground conditions under substantial ground cover and up to 27 bar (900 ft) of ground water pressure. The well known San Andreas Fault lies nearby and has greatly influenced the local geological conditions. This paper will describe the means, methods and materials used throughout the numerous phases of the pre-excavation grouting program. It will also describe many versatile, flexible and innovative drilling and grouting methods and equipment systems utilized to improve performance, save time and costs in constantly changing geological conditions. Considerable lessons learned have been learned while overcoming some extremely formidable ground conditions and safely advancing the tunnels.

Jan 1, 2008

By Brian Fulcher, Michael Bell, Shimi Tzobery, Werner Burger, John Bednarski

The Arrowhead Tunnels Project represents the final portion of a 70 km (44-mile) long water conveyance facility that will bring up to 28 m3/sec (1,000 ft3/sec) of water into Southern California. The 13 km (8-mile) tunneling project is well underway and consists of two, 5.8 m (19-foot) diameter TBM bores through extremely variable geological conditions. The tunnels lie near the base of the San Bernardino Mountains and several significant faults including the San Andreas Fault run within one kilometer (0.6 miles) of the tunnel alignment. Numerous other significant faults cross the tunnel alignment and water pressures in the tunnel have been recorded as high as 20 bar (300 psi). This paper describes some of the problems and challenges encountered and the solutions implemented to advance the two hybrid TBMs under conditions that ranged from hard rock with no water inflows to full-face granular material under 10-bar pressure and in excess of 32 l/sec (500 gpm) inflows. Due to the range and severity of ground and water conditions actually encountered, the Owner-Contractor-Designer team eventually found that adjusting the means and methods to be more responsive—virtually on a day-by-day basis—was needed to suit the conditions

Jan 1, 2007

By Y. Boissonnas

INTRODUCTION, The transalpine rail routes in Switzerland are well over one hundred years old. As the established routes no longer meet the demands of the continually increasing volumes of rail traffic between north and south, two new routes through the Alps were planed. The old Gotthard rail line is in fact a mountain railway. The northern and the southern access ramps?with a maximum speed of 80 km/h and a maximum slope of 2.2%?reach the old Gotthard rail tunnel at an elevation of approximately 1,100 m above sea level. This is approximately 900 m higher than the city of Milan. In 1992, the Swiss electorate people voted with an overwhelming majority in favor of the project to build the new base routes through the Alps. The Swiss voted again in 1998 in favor of the financing proposal for the new infrastructure. Swiss Federal Railways together with the BLS Lötschbergbahn were commissioned for the realization and management of the Gotthard and Lötschberg routes. AlpTransit Gotthard Ltd., founded by Swiss Federal Railways, was given the task of managing the design and realization of the Gotthard route until the start of regular service. In the meantime the shorter Lötschberg Base Tunnel was open to traffic in 2007

By Peter Loehr

Full-face tunnelling machines were introduced into German coal mines 12 years ago. It was aimed to utilize these highly efficient systems to drive mine tunnels in rock so that the large demand for development work in some mines could be met. A characteristic feature of coal deposits in Germany - and particularly in the Ruhr Area - is a thick overburden strata. Access is therefore only possible through vertical shafts. A network of horizontal drivages leading from these shafts open the deposits between the different mine levels. The hardcoal-bearing formations are multi-folded and heavily tectonically stressed. Apart from a few extensive fault zones there are many single faults of different natures in the carboniferous strata. During the course of decades coal mining has penetrated to ever increasing depths. Nowadays coal is mined from depths of between 600 m and 1,200 m. The effects of ground pressure in connection with extremely varying rock strengths and high temperatures are particular difficulties which have to be overcome during drivage work. The first full-face tunnelling machines to be applied in the mines had originally bee deigned and developed for tunnelling projects. Not only the machines themselves, but also the back-up equipment had to be adapted to meet the special demands of German coal mines.

Jan 1, 1983

By Harold J. Schock

This paper describes an experimental method for the monitoring of diesel-generated exhaust gas pollutants in a dead-ended drift for the purpose of assessing the effect of control approaches. Experiments were conducted to determine the relative merits of these ventilation configurations: no auxiliary ventilation, induction ventilation at the entrance to the drift, and ventilation of the dead-ended drift with positive displacement tubing. The drift used in this experimental work was approximately 105 ft. (32.0 mf long and slightly downsloping, with an average height and width of 8 ft. (2.4 m) and 28 ft. (8.5 m1 , respectively. The data were gathered for assessing these ventilation methods and for gathering data to support a computer model of the dispersion and mixing processes. For this drift, it was found that ventilation with positive displacement tubing provided the best removal of diesel-generated pollutants. Induction ventilation appeared to be the least effective of the three methods examined. A comparison was also made between personal monitoring and area monitoring. Results of this analysis showed that in regions of high concentration gradients, it was not possible to get good agreement between point sampling and personal monitoring. In well-mixed areas, good agreement between the two methods of monitoring was obtained.

Jan 1, 1980

By Theophilus Mensah, Kwame Awuah-Offei

Engineers face significant challenges when determining what geometry provides the most profitable and safe stope for extraction. Several techniques and optimization algorithms have been developed in recent years, but most fail to find optimal solutions because they are heuristic or LP-based without efficient geometric constraints. This paper presents a two-dimensional binary linear programming (BLP) model for determining the optimal combination of blocks in a stope that maximizes the economic value of the layout of stopes for a sublevel deposit. The work draws from Queyranne and Wolsey’s (2017 & 2018) formulations of tight constraints for bounded up/down times in production planning problems to formulate novel and efficient geometric constraints along with geotechnical and grade constraints for the BLP stope layout optimization problem. Results from the model indicate that it is possible to formulate efficient shape constraints in LP-based approaches. The model used for the numerical example contained 144 valuable blocks out of 774 blocks, which translates into an economic value of $53.21M. The BLP model selected 60 valuable blocks and 13 waste blocks that met all constraints translating into a maximum economic value of $34.4M in 1.83 hours within a gap tolerance of 0.00%.

Jun 25, 2023

In late November 2010, a Laotian landmark was achieved for the country?s first tunnel boring machine - (TBM) driven tunnel. Italian contractor CMC di Ravenna celebrated the breakthrough of a 7.6-m- (25.1-ft-) diameter Robbins single shield TBM for a hydroelectric tunnel on the Nam Theun River. The Theun Hinboun expansion project and 5.5 km (3.4 miles) headrace tunnel will bring much needed power in-creases to Laos and Thailand. . ?Since this is the country?s first machine, it has awakened people?s curiosity and interest. We had experienced Italian and Chinese crew members, but we also trained many Lao workers during the course of the project, as this was something they had not seen before,? said Luca Barbàra, Far East Manager for CMC di Ravenna. The machine broke through on Nov. 21 into an exit shaft close to the intake structure on the river. The machine is now being disassembled and removed - CMC hopes to use it on upcoming projects in the region. Due to the current rainy season and relative low level of the tunnel, the last 100 m (330 ft) up to the intake structure will be completed using drill-and-blast after the waters recede below the tunnel invert.

Jan 1, 2011

By L. K. Eigenbrod

Throughout the mining industry, pneumoconiosis is one of the most severe occupational health problems being faced. The goal of completely eliminating pneumoconiosis as an occupational health hazard was underscored by the Federal Government with its enactment of Public Law 91-173 (Federal Coal Mine Health and Safety Act of 1969). Under this law, permissible dust level standards will be placed at 2 mg/m3 in mine atmospheres by December 30, 1972. The mining industry is thus faced with the tremendous technical challenge of achieving this level. Two basic questions can be raised with regard to this legislation. First, does a maximum dust concentration of 2 mg/m3 prevent the occurrence of pneumoconiosis? Secondly, can this dust standard be achieved using presently available methods and equipment? A precise answer to the first question has not yet been developed by the medical profession. Studies are continuing on the origin, prevention, and therapy of pneumoconiosis, and permissible dust levels could become even lower as medical evidence accumulates. The mining industry has addressed itself to the problems of dust con-tro1 for many years as related to personnel health, explosive mixtures, visibility, and machinery damage. Dust control methods being employed involve

Jan 1, 1971

By Verya Nasri, Behrouz Esmaeilkhanian, Mohammad Motallebi

Réseau Express Métropolitain (REM) is the new Light Rail Transit (LRT) network of Montreal, Canada. This new LRT network uses a century-old Mont Royal Tunnel (MRT) to connect Downtown Montreal to the north side of the Island of Montreal by passing through Mount Royal Mountain. This railway double track horseshoe tunnel is approximately 5 km (3.1 mi.) long, 8.8 m (29 ft.) wide and 5.5 m (18 ft.) high, with a constant 0.6% grade. Due to different geological characteristics of the surrounding ground, varied from hard rock to soft soil, different cross sections and excavation methods were adopted for construction of this tunnel. In order to use MRT in the modern transit system, the tunnel needed to be inspected, rehabilitated and be compliant to the recent safety standards. This paper presents a summary of history and characteristics of the existing tunnel plus the implemented steps to upgrade the tunnel. It includes the details of the structural inspection and rehabilitation methods of the tunnel. Further, this paper summarizes the procedures for the space proong, construction of the separation center wall, and the tunnel enlargement. It also describes parts of complications encountered during the construction and solutions implemented to tackle these issues.

Jun 23, 2024

By Michel Claisse, R. P. Goel, André J. Rancourt, Kent Murphy

The Malana Hydroelectric Project is a private development located in HimachalPradesh State, India that was commissioned in June 2001. The plant was built and is owned by the Malana Power Company, a subsidiary of the Bhilwara Group of New Delhi. With a total head of 400 m and nominal capacity of 86 MW, the plant is capable of generating 360 GWh annually. The 3,1 km long, 4,0 m diameter power tunnel was designed to be excavated by conventional drill and blast methods. Contrary to traditional practice in India for pressure tunnels of providing a concrete lining, the Malana tunnel was finished mainly with shotcrete. In this way, the tunnel was completed in a period of18 months, a record for recent projects in the Himalayas, and at a cost substantially below that of conventionally lined tunnels. An interesting aspect of the project was the design of the steel tunnel liner linking the power tunnel to the penstock. The length of the liner was fixed finally on the basis of in-situ testing using both hydraulic jacking and doorstopper tests to evaluate the ability of the rock to withstand the internal pressure of4,0 MPa that exist near the downstream end of the tunnel.

Jan 1, 2003

By C. J. Myers, D. L. McKinnon, A. A. Dasys

In 1988, the National Institute of Occupational Health and Safety (NIOSH) published an information bulletin stating that whole diesel exhaust should be considered a probable carcinogen. Since then, regulations across Canada and the United States (Mine Safety and Health Administration, MSHA) have looked at appropriate exposure limits for underground mine workers. In Canada, an interim standard of 1.5 mg/m3 Respirable Combustible Dust (RCD) has been adopted by some provinces and is being looked at by others. MSHA is considering levels as low as 0.5 mg/m3 soot. Golden Giant, being aware of regulatory developments, decided to look at means of reducing diesel particulate on thier large production machinery. This machinery (LHDs and haulage trucks) is powered by Detroit Diesel 71N Series engines and is used to produce 3000 tonnes of ore/day with a longhole mining technique. Having looked at the various control technologies, it was decided to evaluate the potential of using diesel particulate filters with a copper-based fuel additive for regeneration (the process by which collected particulate is burned off). This paper outlines the control technology used and the results of the field evaluation indicating the benefits to the underground mine worker.

Jan 1, 1993

By Gunnar Sparrman, Börje Ahlgren, Sten Rosenström

Starting in 1967 two major hydroelectric power projects have been implemented in East Africa viz. Kafue Gorge in Zambia and Great Ruaha in Tanzania. The two projects have similar characteristics and each consists of an underground power plant, a dam in connection with the power plant and a reservoir dam. The power plants are both designed and constructed according to principles applied in Scandinavia for a long time. Each consists of a headrace of a horizontal unlined rock tunnel with a length of about 10 km, vertical penstock shafts, machinery and transformer halls in large rock caverns and a tailrace of an unlined rock tunnel with a length of about 1 km. The head of the power plant of Kafue Gorge is 400 m, Great Ruaha 175 m, the capacity is 900 MW and 200 MW respectively. Both plants were executed in one stage, but building and erection works were made in two stages. However, the power plants show some interesting differences in design. The power plants are briefly described in the following, special regard being paid to the excavation works. GEOLOGY General The foundation of Eastern and Central Africa is made up of ancient crystalline rocks, consisting of sediments, lavas and intrusives, mostly intensively altered by repeated metamorphism. This repeated metamorphism - dynamic, ther-

Jan 1, 1979

By Y. C. Lo

This paper attempts to answer whether or not the mill performance at Bougainville could have, in fact, been predicted by the population balance approach, or whether other special considerations are required to explain their behavior. In recent studies, the plant tests were performed at Bougainville and batch tests were carried out at the Utah Comninution Center. In all tests power measurements were made and several levels of energy input to grinding were evaluated. Also, tracer tests were performed for mill residence time determination. The performance of Bougainville's 5.5 x 6.4 m mill has been very successfully predicted by population balance methods. The prediction errors are only about 1% on product size distribution and 4% on power with a mill volume scale-up of 3790 to 1. It is significant that this approach will reduce the risk of failure in large mill design that has been recognized in traditional methods.

Jan 1, 1987

By P. J. Ryan

Phelps Dodge’s Candelaria copper-gold mine is located 20 km (12miles) south of Copiapó in northern Chile’s Atacama province (Region III) (Fig. 1). The Candelaria Mine is about 800 km (500miles) north of Santiago and 75 km (47 miles) east of the Pacific Ocean. Its elevation is 600 m (1,970 ft) above sea level. The Copiapó River Valley is 6 km (4 miles) northeast of the mine site. It is the only major source of water in this arid region. The average rainfall is 14mm/a (0.5 in./year). During 1995, the mine produced 521.4 kt (574,800 st) of copper concentrate containing 150 kt (165,000 st) of salable copper and 3 t (98,800 oz) of gold. The 1995 unit cash cost was less than 50 cents/lb of copper. This makes Candelaria one the world’s lowest cost copper producers.

Jan 1, 1996

By J. A. Farinelli

In the Appalachian region of the United States, approximately 40% of the underground coal reserve base exists in seams 0.7 - 1.1m thick. These seams are, in general, often of premium quality and are frequently accessible through above-drainage drift-type openings. Unfortunately, there are no apparent advantages to mining thin seams, if quality is disregarded. The thin-seam mine is faced with the same legal and economic pressures as any other underground coal mine. But in addition to these common problems, thin-seam operations must also deal with the unique problems associated with mining at such a restrictive height. Small-scale, short-lived operations appear to be the most feasible means of mining these reserves. The purpose of this paper is to evaluate the production and safety potential of various thin-seam mining systems. Recommendations will be made regarding present and future thin-seam operations.

Jan 1, 1987

By S. S. Klima, H. Jiang, T. W. Beck, Y. Zheng

Researchers at NIOSH’s Pittsburgh Mining Research Division (PMRD) performed comparative testing of six different water sprays at pressures ranging from 689 kPa (100 psi) to 6,895 kPa (1,000 psi) in a 14.5-m3 (512-ft3) confined dust chamber. Testing was conducted to determine the effect of various pressures on each spray’s respirable coal dust knockdown ability. It is known that higher water pressures are typically preferred for lowering airborne dust concentrations, but it was important to determine at what pressure range the dust knockdown ability of each spray plateaus or reaches its minimum dust concentration. Results from this testing showed that several sprays saw up to 100% decrease in dust concentrations during the five-minute water spray testing period, with some occurring well below the maximum 6,895 kPa (1,000 psi) spray pressure.

Feb 1, 2023

By Stanley J. LeFond

The Republic of Botswana, one of the newer countries of southern Africa, attained independence on September 30, 1966. It covers an area of about 225,000 square miles (582,000 square kilometers) which makes it slightly larger than France, or slightly smaller than Texas. It is bounded by Zimbabwe, the Republic of South Africa and Namibia, including the Caprivi Strip. Angola and Zambia are close neighbors. (Map 1). Botswana lies at the center of the southern African plateau at a mean elevation of 3,300 feet (1,000 m). It is a natural habitat for most species of African fauna. The rolling sands and extensive grasslands of the Kalahari Desert cover the southwest. The climate is sub- tropical. Summers, although tempered by north- easterly breezes, are hot, but mean maximum temperature seldom rises above 100°F (38°C). Winters are dry with wide temperature variations, which often give rise to frosts.

Jan 1, 1981