Search Documents

By Eivind Grøv

"INTRODUCTION Tunneling and underground excavation is related to handling of uncertainties, risks associated with geological conditions are significant and ‘unexpected geological conditions’ often claimed. This fact was brought to the table long ago, and ITA (the International Tunnelling and Underground Space Association) published its 25 Recommendations on Contractual Sharing of Risks in 1988 (Ref. 1). This public-cation constitutes an important asset to the tunneling industry in terms of being a guideline for those working with contractual issues, even today almost 30 years after being published. A more recent document is the ITIG code of practice for risk management of tunnel works from 2015 (Ref. 9). Various countries or geographical regions have their own view and tradition on risk sharing and tunnel contracts. In Scandinavia unit rates contracts are most commonly used with bid-build model, it shares risk between owner and contractor, owner retains the risk for geological conditions while contractor carries risk for performance efficiency. Rock strengthening is determined assessing rock mass quality encountered at tunnel face. Grouting is applied to stem water. Actual quantities may differ from the contract’s BoQ but a flexible contract with remuneration is installed to enable adjustment of actual quantities. Variations of quantities involve a clause to adjust construction time. Unit price contracts deals with expected and foreseen still ‘unexpected geological conditions’, if the ‘unexpected’ element results in variations in quantities. Work activities have quantities and ‘standard capacities’ for regulation of construction time. Variations in quantities are expected in tunnelling and hardly deserve the term ‘unexpected’. If truly unforeseen geological features necessitate work not included in the BoQ, then the contract must be supplemented and can be said to be inappropriate. Fixed price contracts may not provide the intended predictable cost and is as such also inappropriate in the view of a risk sharing principle, once the geological baseline proves to be incorrect. ‘Adjustable fixed price’ contracts, combining unit rate and fixed price, may prove suitable."

Jan 1, 2016

By Reinhard Gertl, Maximilian Weithaler, Harald Kammerer, Juan Pablo Muñoz, Juan-Carlos Rueda

The Guillermo Gaviria Echeverri tunnel and its access roads project in Antioquia, Colombia is a mega infrastructure project that includes a road network with the longest tunnel in Latin America and several short tunnels, the latter being the focus of this study. The design of the project required careful consideration of several special factors, such as the tunnels’ steep slopes of up to 5%, high fire load of 100 MW, bidirectional operation, and short lengths that make it difficult to place ventilation equipment. The combination of all these parameters cause a challenging design problem for the ventilation systems and smoke control of the short tunnels. To address this challenge, a risk assessment study was conducted to support the design of a new and innovative ventilation strategy that deviates from relevant guidelines and standards, like the Austrian RVS [1][5][6] or the German EABT [8] in order to provide a customized solution for this particular project. This strategy resulted a cost-effective solution, that allowed a reduction in the number of required jet fans and at the same time reaches or reduces the risk level compared to traditional ventilation strategies.

Jun 13, 2023

By Samuel J. Gambino

Preliminary recommendations for the Upper Northwest Interceptor 1&2 specified installation of reinforced concrete pipe using pipe-jacking methods. However, a larger one-pass tunnel constructed using precast segmental lining would provide additional storage volume. The risk of encountering unexpected conditions or events and the resulting cost impacts could differ significantly for these two options. A probabilistic life-cycle cost analysis of these alternatives was performed. This paper discusses the construction alternatives considered, the risk assessment methodology used to evaluate these alternatives, the input parameters and risk factors used in this analysis, and the recommended project which is currently being constructed.

Jan 1, 2008

By Reinhard Gertl, Soroush Dabiri, Juan-Carlos de Rueda

The Tunnel of Guillermo Gaviria Echeverri, spanning 6.05 miles, will be Latin America’s longest road tunnel, is currently under construction in Colombia’s Antioquia Department with a single bidirectional tube connected to a parallel rescue tube through multiple cross-passages. The study faces challenges in implementing the prescriptive semitransversal ventilation system due to design restrictions. Different ventilation concepts are eplored to nd the most suitable system for regular operation and re scenarios. A quantitative ris assessment evaluates each alternative system and identies the longitudinal ventilation system, accompanied by ris mitigation measures, as the safest choice, since it surpasses the prescribed semitransversal ventilation concept.

Jun 23, 2024

By Franco Oboni, Iain G. Bruce

The design of tailings containment structures relies on well-understood engineering methods being applied consistently. Unfortunately, not all facilities are designed or managed to the same level of competency. To standardize procedures, the Mining Association of Canada (MAC, 1998) prepared a “Guide to Tailings Management.” It recommended review of designs and an assessment of the risks associated with tailings impoundments be implemented during all phases of amine life. This paper describes how the quantitative risk assessment (QRA) process can be used to define risks associated with the design, construction and operation of a tailings management facility. And it discusses how, once the risk tolerability curves (RTC) are defined for a project, they can assist the risk management (RM) process.

Jan 1, 2002

By John Waggoner, Steve Klein, John Townsend, Jay Arabshahi

The Riverside Badlands Tunnel is a 13 km (8 mile) long segment of the Inland Feeder Project. This 3.65 m (12 ft) finished diameter water tunnel presented many challenges that had to be overcome to take the project from concept to reality, not the least of which were the diverse ground conditions. Construction of the tunnel was carried out by a single tunnel boring machine (TBM) in one tunnel drive. The project is considered a success due to the accurate baseline established for the ground conditions; the approaches used to mitigate adverse conditions; and the appropriate use of TBM excavation methods, which achieved rapid advance rates despite the challenging ground conditions.

Jan 1, 2003

By Henning Schwarz, Faisal Al Arifi, Anas Almousa

"The Riyadh Metro Project forms part of a complete new public transport system integrated in the urban planning and development of the fast growing capital city of the Kingdom of Saudi Arabia. The Design & Build project consists of 176 km of a new metro network with 57 km of double track single tunnel infrastructures, spread over six metro lines. During the design phase, geological, hydrogeological, geotechnical and geophysical site investigations were undertaken to chart the, previously uncharted, underground construction space. Different TBM solutions were selected for implementation taking due consideration of the ground conditions of each metro line. The results obtained from deep excavations for underground stations and analysis of the TBM tunneling data will be used as key input for future tunneling projects in the Riyadh and the Kingdom of Saudi Arabia. The present paper details the design conditions and presents the solutions for large diameter tunnels in karstic limestone. INTRODUCTION The High Commission for the Development of Arriyadh was established in 1974 as the organizational, planning, executive and coordinating body responsible for the development of Riyadh. Arriyadh Development Authority (ADA), established in 1983, is the High Commission’s executive, technical and administrative arm. The ADA is responsible for implementing the High Commission's organizational, planning, executive and coordinating decisions and missions (ADA 2015). One of the remits of the ADA is the preparation and execution of a transport plan for the city. The metro network is planned to be the backbone of the public transport system developed as part of the King Abdulaziz Project for Riyadh Public Transport in Riyadh. With six lines and a total length of 176.5 km (Table 1) and 85 metro stations, the metro network will cover most of the densely populated areas, public facilities, and the educational, commercial and medical institutions. The network will connect the King Khalid International Airport, the King Abdullah Financial District, main universities, Riyadh downtown and the public transport center. The public transport plan includes a future bus network with 22 lines on 1200 km and 6765 stops that will be the main feeder for the Riyadh metro network; it will also be the main mode of transportation within and around Riyadh districts (ADA 2015)."

Jan 1, 2016

By Henning Schwarz, Ade Ogunsola, Anas Almousa

"The Riyadh Metro, commissioned by Arriyadh Development Authority “ADA” - the executive arm of The High Commission for the Development of Arriyadh -, forms part of a new public transport-system of Saudi Arabia’s fast growing capital city. The Design & Build project consists of 176 km of Metro Line with 57 km of tunnels. Beyond the Design and Construction, an additional aim of the ADA is to introduce up-to-date methodologies and improve safety in construction projects. A systematic dilapidation survey of buildings and infrastructures was a prerequisite for designing the required instrumentation and monitoring tools. Site investigations required of existing methodologies and the use of geophysical methods for achieving reliable results. Large diameter TBM tunneling is challenging in hot weather conditions and karstic ground. The present paper shows how modern technologies for underground construction are introduced into the local industry and gives an outlook on future projects in the Kingdom of Saudi Arabia. INTRODUCTION Riyadh, the capital city of the Kingdom of Saudi Arabia, is a fast growing city with more than 5.7 million inhabitants. The growth of the city is linked to the recent history of the Kingdom, where some initial milestones from the 1950’s can be highlighted: Revenue generation from the exportation of oil from the Kingdom; downstream investment of oil revenue in the reconstruction and development of the Kingdom; a general plan for the settlement of the Bedouins; the provision of a public electricity network for the city; the opening of the Riyadh - Dammam railway corridor providing a link from the capital to the Eastern Region; the commissioning of Riyadh airport (converted to Riyadh airbase, after the opening of King Khalid International Airport in 1983); and the relocation of ministries and other central government agencies in 1955. In 1974, The High Commission for the Development of Arriyadh was established as the organizational, planning, executive and coordinating body responsible for the development of Riyadh. Arriyadh Development Authority “ADA”, established in 1983 is the High Commission’s executive, technical and administrative arm. The ADA is responsible for implementing the High Commission's organizational, planning, executive and coordinating decisions and missions. The ADA’s president is a member of the High Commission (ADA 2015). One of the remits of the ADA is the preparation and execution of a transport plan for the city of Riyadh."

Jan 1, 2016

By Martin Langenderfer, Catherine Johnson, Alexander Douglas

Mine haul roads degrade rapidly due to extreme loads on suboptimal construction materials. Unmanned aerial vehicles (UAV) are suited to quantify large-area road-network conditions, such as surface roughness, defects and grade to optimize remediation of poor conditions and reduce overall costs. Mine haul roads present unique challenges, such as material type and edge characteristics, to automatic road detection that often fails, requiring manual road input. This research work proposes a new method using the road center determined by the principal curve of a haul truck’s path. Analysis grids were created from this center line. A dense point cloud from UAV photogrammetry was generated and multiple linear regression analysis was conducted on each individual grid. The root-mean-square error in each grid indicates the surface roughness, and the change of slope between grids indicates the road grade inconsistencies. This method was applied to 26 road sections, and the results were validated by images taken from the truck operator’s vantage point. Critical defects were identified including excessive pothole formation, corrugation, depressions retaining water, and narrowing of travel lane. The results demonstrate this is a valid method of road identification and quantification of road defects at a mine site.

Apr 1, 2024

By David Caiden, Petros Fortsakis, Alan Hodgkinson

"1. INTRODUCTIONDo contractual practices affect project outcome? Can better contractual practices improve the likelihood of project success? The consensus amongst experts is that better contractual practices really do improve project outcomes. With this in mind the members of the International Tunnelling Association (ITA) Working Group 3 on Contractual Practices (WG3) pooled their collective knowledge to publish in 2011 the document entitled The ITA Contractual Framework Checklist for Subsurface Construction Contracts (ITA Working Group 3, 2011). Written for projects involving significant subsurface works, e.g. tunnels and caverns, the ITA Framework Checklist explains the major contractual issues that must be considered to ensure a successful project. Its goal is not to specify how each issue should be resolved, but rather to highlight the issues and give recommendations on how they should be addressed. The Checklist is compatible with, and provides guidance for reviewing, standard contracts such as FIDIC and NEC. One of the authors is a co-author of the Checklist and has contributed to previous papers describing the Checklist and its applicability to hydropower projects (Hodgkinson & Wilson 2014, Hodgkinson & Wilson 2015). The Checklist identifies a series of issues that should be contractually defined, which can be summarized as follows: •,Methods for dealing with geotechnical uncertainties should be defined in the contract •,There should be an appropriate level of geotechnical/geological investigation •,Sufficient mobilization periods should be allowed •,Sufficient time should be allowed for testing and commissioning •,Procedures for timely dispute resolution should clearly defined •,Quality and performance requirements should be clearly defined and measurable •,Provision should exist for cost consequences of unforeseen circumstances •,Dispute resolution processes should be clearly defined •,Payment processes should be fair and clearly defined •,Risk should be clearly allocated and parties should be able to bear the risks they carry •,There should be a mechanism for adjusting payments according to conditions •,The risk management approach should be clearly defined •,Admeasurement or unit price approaches are recommended •,The responsibilities of each party must be clearly defined •,The consequences of non-performance should be clearly defined •,The construction programme (schedule) should be realistic."

Jan 1, 2016

By Gary D. Aho

The United States on a daily basis no consumes about 15MM barrels (2.38 x 106m3) of oil; 5MM (0.79 x 106 m3) of this is imported. This compares tai a daily consumption of 18MM (2.86 x 106 m3) in 1980 when we imported 8MM (1.27 x 106 m3). We are producing the 10MM barrels (1.59 x 106 m3 ) of conventional oil at home from what amounts to just 2% of our domestic energy reserves. Nearly 90% of our total domestic energy reserves occurs in solid forms such as coal, oil shale, and tar sands; this is more than enough to meet our needs for the next 100 years. Worldwide, oil shale is second only to coal as a potential source of energy and the U.S. has approximately one-half of the world oil shale reserves which average over 25 gallons per ton (10.43 x 10-2 L/kg). Since the United States has immense oil shale resources, including some of the richest in the world, and since oil shale produces a superior transportation fuel, it would seem logical that the U.S. would be prudently developing this domestic resource. Unfortunately, despite over 50 years of research and a number of false starts, there is not a commercial shale oil industry in place today. There are a number of recurring roadblocks which have hindered private industry's efforts to develop oil shale and we will look at some of these.

Jan 1, 1983

By H. Copur

Roadheaders have become widely used in underground mining and tunneling operations because they offer the flexibility to excavate soft- to medium-strength rock formations. A critical issue in successful roadheader application is the ability to develop accurate and reliable estimates of machine production capacity and the associated bit costs. Increased pressure to improve productivity and lower costs in the mining and civil construction industries has been the driving force behind the more wide- spread use of mechanical excavation systems. This has caused both industries to move away from the conventional drill and blast methods. Additional benefits of mechanical mining include improved safety, reduced ground support requirements and fewer personnel. These advantages, coupled with recent enhancements in machine performance and reliability, have resulted in mechanical miners taking a larger share of the rock excavation market. Roadheaders are the most widely used underground partial-face excavation machines for soft- to medium- strength rocks, particularly for sedimentary rocks. They are used for development and production in soft rock mining (main haulage drifts, roadways and crosscuts), particularly in coal, industrial minerals and evaporitic rocks. In civil construction, roadheaders are used to excavate railways, roadways, and sewer and diversion tunnels in soft ground conditions. They are also used to enlarge and rehabilitate underground structures. Their ability to excavate almost any profile opening also makes them attractive to those mining and civil construction projects where various opening sizes and profiles are needed. In addition to their high mobility and versatility roadheaders are generally low capital cost systems com- pared with most other mechanical excavators. Because of higher cutting-power density due to a smaller cutting drum, roadheaders can excavate rocks harder and more abrasive than continuous miners and borers.

Jan 1, 1998

By H. Copur

Roadheaders offer a unique capability and flexibility for the excavation of soft to medium strength rock formations, therefore, are very attractive in underground mining and tunneling operations. This paper reviews the importance, technological developments and application limits of roadheaders based on the case histories, which are compiled in a database including different roadheaders in various geological conditions. The paper also discusses the database and empirical performance prediction studies regarding instantaneous cutting rates and bit consumption rates.

Jan 1, 1998

By James S. Goff, Stephen J. Navin, Wesley W. Moulton

The White River Shale Oil Corporation (WRSOC) is developing a prototype oil shale facility on Federal Lease Tracts Ua and Ub located in northeastern Utah. This paper covers the successful driving of 1,525 m (5,000 ft) of dogleg downgrade decline with a 70-ton Paurat Roadheader mining machine and a conveyor muck-handling system. Ground support is with rock bolt and shotcrete; welded wire mesh is optional. The Upper Decline of 3.89 m by 8.69 m (12.75 ft by 28.5 ft) was mined through the Uinta Formation sandstones and shales in 210 days. The sandstones have a compressive strength in the 48 MPa (7,000 psi) range with a few bands of shale up to 137.8 MPa (20,000 psi). Green River Formation dolomitic marlstone with some sandstone lenses was mined in the Lower Decline 3.89 m by 5.64 m (12.75 ft by 18.5 ft) in 175 days. The Green River marlstones are tough massive formations ranging up to 206.8 MPa (30,000 psi). Roadheaders for use on steep slopes must be modified to accommodate the particular problems associated with mining downdip. The paper concentrates on the application of Roadheaders to steep slopes and the problems of mining tough materials such as marlstone. The paper also shows the advantage of using the method of excavation on long drives.

Jan 1, 1985

By Levent Ozdemir

An extensive study involving laboratory testing and computer modeling has been performed to assess the technical and economic feasibility of utilizing the recently developed minidisc cutters on roadheaders for hard rock mining. The results show that heavy duty roadheaders fitted with minidiscs can excavate hard rock formations at acceptable production rates and cutter costs. This paper presents and discusses the results of this study together with the ongoing developmental efforts of this technology, which include laboratory testing of a roadheader cutting drum with minidiscs and full scale field testing of a machine in hard rock

Jan 1, 1995

By Louis A. Sandbak

Drift excavation by boom-type roadheaders in the San Manuel and Kalamazoo sulfide copper ore bodies has been successfully demonstrated. Geomechanical rock classification in conjunction with detailed geologic mapping has been necessary to assess roadheader performance, and to predict advance rates in the varied rock classes in the San Manuel block caving mine. Rapid excavation and less fractured ground are obvious advantages of roadheader drift excavation over conventional drill and blast techniques. The geomechanical system of Engineers International (1984) can be an effective roadheader performance and ground support tool.

Jan 1, 1985

By D. Kwietnewski

The 4th bore of the Caldecott Tunnel is a 50-ft horseshoe shaped highway tunnel located in the hills east of Oakland, California. Tunnel excavation was mostly completed using one of the world?s largest commercially available roadheaders, a Wirth T3.20. The geologic profile included seven different geologic units, which displayed a range of different behavior with regard to excavation and initial support. Following a brief introduction to the excavation and support methods, this paper will discuss roadheader performance in the various geologic units encountered during excavation. Comments will also be made concerning the relationship between the roadheader method of excavation and observed ground convergence during excavation.

Feb 27, 2013

By Glen Church, Don W. Deere, Christoph M. Goss

The Standley Lake Dam Rehabilitation Project in Colorado included the complete replacement of the outlet works. This required two 1.8m (6 ft) diameter microtunneled wet lake taps, 380m and 186m (1246 ft and 636 ft) long, a permanent valve shaft 12.2m(40 ft) wide and 32m (105 ft) deep, and a 3.5m (11.5 ft) diameter (962 foot long) outlet tunnel driven with a roadheader. The tunnels were driven in low-strength, expansive, and slickensided claystone. The paper addresses the site investigation, shaft construction, roadheader performance, shotcrete placement, tunnel convergence, long distance microtunneling, and wet lake taps.

Jan 1, 2005

By J. S. McAlpine, J. Matousek, W. Muir, P. Downey, K. Major

The Golden Bear refractory gold ore roasting operation is located at Huddy Lake, in northwestern British Columbia, about BO km northwest of Telegraph Creek (see Figure 1). The mine access road, used for supplies delivery, was developed by Golden Bear and consists of a radio controlled 155 km gravel road originating at Highway 114. Hine operations are based on a two week in, two week out rotating shift schedule with personnel transport by chartered aircraft from Vancouver, Whitehorse or the 3 Talthan conmunities. The site runway Is located adjacent to the tailings impoundment.

Jan 1, 1992

By R. G. Reddy

Chemical and structural changes occurring during the roasting of refractory gold ores were investigated. Effect of temperature on oxidation behavior of ores was analyzed using TGA, DTA and X-ray diffraction methods. The experimental results showed that the carbon in the ore has to be oxidized to a minimum value before any appreciable oxidation of sulfur occurs. Oxidation rates as a function of temperature were calculated. Optimum conditions under which a successful roasting of the refractory gold ores can be obtained are discussed.

Jan 1, 1990