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By Dong-mei Zhang, Feng Zhang, Hong-Wei Huang, Qiang Huang, Bin Ye

"1. INTRODUCTION Nowadays, many cities around the world have constructed metro tunnels to alleviate transportation pressure from rapid urbanization. In soft soil areas, metro tunnels are usually constructed by shield-tunneling method due to its high efficiency and little disturbance to environment. However, the tunnels may show significant post-construction settlement after several years of operation. Take Shanghai Metro line 2 for example, the maximum longitudinal settlement reached 160mm after ten years of operation, shown in Figure 1. When analyzing varying factors that contribute to the long-term settlement of tunnels, the effect of cyclic loading from train vibration is rarely taken into consideration for most researches only focus on the influence of leakage problems in the tunnel while neglecting train vibration induced leakage and resulting settlement. It’s true that metro tunnels from shield-tunneling method are prone to have leakage problems due to the special structural configuration. Furthermore, trains move hundreds of times inside the tunnel every day, which inevitably will cause accumulation and dissipation of excess pore pressure. When the excess pore pressure dissipates, tunnel settlement induced by train vibration occurs(Deng F H, 2007). Although researchers (Zheng et al., 2005; Wongsaroj et al., 2007; Mair, 2008; Shin et al., 2012; Zhang et al., 2012, 2015) conducted extensive numerical analysis on the relationship between tunnel settlement and relative permeability of tunnel to surrounding soil by treating tunnels as permeable media, their attention was only paid to the tunnel settlement from reduction of hydrostatic pressure in the ground, rather than from the dissipation of excess pore pressure generated by train vibration. Therefore, the influence of train vibration on the long-term settlements of metro tunnels is still not clear."

Jan 1, 2016

By Steve Wirch, Robert Jankowski

The issue of dust control in underground coal mines has been extensively studied by both government and industry. This research work has resulted in many techniques which control the dust or help miners avoid it. Control techniques either prevent the dust from becoming airborne or cleanse the air before it can be inhaled. Avoidance measures minimize the exposure of miners to the airborne dust by blowing the dust away from work areas or making it unnecessary for a miner to occupy a dusty region. One of several successful dust control measures in continuous miner sections is the use of a machine mounted scrubber which cleanses the air and helps to prevent the contaminated air from reaching areas frequented by mine personnel. Research on the application of scrubbers on longwall shearers began in the 1970s and continued into the 1980s. The most successful projects showed only moderate improvement when a scrubber system was mounted on a longwall shearer, and the less successful projects actually increased worker dust levels. There are many reasons that scrubbers have not been successfully applied on longwalls. The most significant of these is that longwalls have across the face ventilation and generally have high face air flows. Scrubbers tend to work best when they are the primary cause of ventilation. Therefore, their capture efficiencies on longwalls tend to suffer because of the exposure of the drums to the primary airflow. Other reasons scrubbers have not been implemented on longwall s include the successful application of an excellent water spray system, effective cutting techniques, and dispersion of dust sources. These techniques can help control drum generated dust, increase production, and limit the relative effectiveness of a scrubber.

Jan 1, 1995

By Frank E. McCall, Michael A. Trevits, Fred Garcia

The U.S. Bureau of Mines investigated the influence of atmospheric pressure changes on methane gas migration through mine seals at a mine site located in the Pittsburgh Coalbed. The mine gained access to a coal reserve through part of an abandoned mine and constructed nine seals to isolate the extensive old workings from the active mine area. Underground problems were experienced when atmospheric pressure fell, causing methane gas to migrate around the seals and into the active workings. During mining operations, methane gas levels exceeded legal limits and coal production was halted until the ventilation system could be improved. When mining resumed with increased air flow, methane gas concentrations occasionally exceeded the legal limits and production had to be halted until the methane level fell within the mandated limit. To assist the ventilation system, a pressure relief borehole located in the abandoned workings near the mine seals was proposed. Preliminary estimates by a gob gas simulator (computer model) suggested that a 0.76 m (2.5 ft) diameter pressure relief borehole with an exhaust fan would be necessary to remove enough methane from the abandoned area so that the ventilation system could dilute the gas in the active workings. However, by monitoring methane gas emissions and seal pressure, during periods of low atmospheric pressure, the amount of methane gas that migrated into the active mine workings was calculated. Researchers then determined that a relief borehole, 20.3 cm (8-in) with an exhaust fan could remove at least twice the maximum measured volume of migrating methane gas. Because gas concentrations in the abandoned workings could potentially reach explosive limits, it was proposed that the mine eliminate the exhaust fan. Installation of the recommended borehole and enlarging two other ventilation boreholes located in the abandoned area reduced methane gas leakage through the seals by at least 63%.

Jan 1, 1995

By W. A. Hustrulid

Introduction A problem that has faced mining engineers and mining geologists for many years is how to best explore a particular prospect so that the basic decision as to whether the material present is ore or only high-grade rock can be made with some confidence. It is obvious that one could not begin a large scale mining program on the basis of tests made on a few hand samples. On the other hand, one could not be 100 percent certain as to the average grade or tonnage before beginning development, as this would require the orebody to be mined out in the sampling process. The basic objectives of the exploration program can be stated as (1) to reduce mining risk; (2) to lessen the cost of development; and (3) to increase the profits of mining. The exploration program should be terminated when these objectives are no longer being met. The construction of tunnels is a specific mining operation. In the exploration program one should gather the data needed to determine (1) the type of excavation technique(s) to be used; and (2) the rate of advance that might be expected. As in the evaluation of an orebody, with the data collected it should be possible to estimate mining costs and project life. Unfortunately, at the present time, it is not possible to do this at least when dealing with medium to hard rock types. The reason for this, it is felt, is basically the inability to identify what specific rock mass properties are of use in tunnel design and to specify how these may be obtained in an exploration program. In short, the exploration program should be designed to give information regarding both the volume (length) and 'grade' (in

Jan 1, 1997

By A. C. Nixon, A. D. S. Gillies, Hsin Wei Wu

Ventilation and refrigeration strategies for the 3000/3500 orebodies, Mount Isa Mines, Australia were reviewed. The orebodies lie between 1,200 and 1,800 m below surface and are characterised by steep geothermal gradients, intensively mechanised stoping methods and high ambient air temperatures in summer. Providing acceptable working conditions under these situations is difficult and costly. The ventilation air quantity required in the 3000/3500 orebodies exceeds 550 m3/s when the production rate is greater than 2.5 million tonnes per year. The maximum quantity that can be supplied and exhausted using the existing intake and return ventilation system is estimated at about 630 m3/s. For production rates greater than 3 million tonnes per year, either new intake and return airways will need to be developed or innovative approaches such as controlled partial recirculation used. A description is given of technical and economic investigations conducted at Mount Isa into controlled partial recirculation. During these investigations, a major field trial of a controlled partial recirculation system was undertaken with results indicating that an acceptable working environment can be achieved practically and economically utilising this approach. The cost involved in controlled partial recirculation for supplying the required ventilation quantity when the production of 3000/3500 orebodies exceeds 3 million tonnes per year is examined. A cost comparison between recirculation and other conventional alternatives such as new surface shaft or underground booster fans is included. The results indicate that the option of a new surface shaft will incur a high initial capital cost and moderate annual operating costs. The alternative of underground booster fans will necessitate a moderate capital cost and very high operating costs. Controlled partial recirculation, in this case, offers both the lowest capital and operating costs of the three options evaluated.

Jan 1, 1995

There are bound to be changes with age, so I should not have been surprised or disappointed when what I had considered as high ad- ventures were much fewer and more widely scattered in the last 20 years of my long and active business life. But such adventures came until I was past 80 years of age and no one could expect more than this. Frequent visits to mines in this country and Canada and directorships in Bralorne and its subsidiaries, Homestake Mining Co., Bradley Mining Co., and the Bunker Hill Co.; and Copper Range Co. and its great new White Pine mine in Michigan, lasted far beyond the usual retirement age. The least happy part of my last two decades of active life was the death or sickness of many of my old friends. Hubert d'Autremont, whose friendship no one could replace, died suddenly in 1946. Henry Carlisle and Temple Bridgeman, for many years office associates, had heart attacks that cut down their activities far too soon. Many other less intimate friends died or became ill, but I knew that with advancing years such losses were inevitable. These memoirs would be endless if they covered all of the unusual work and associations I found in the last 20 years. So I must confine the rest of my recollections to expeditions that would have thrilled any engineer at any time. Masaro Mine, Mindanao, Philippines The first of the four "high adventures" came late in 1949, when I was 65 years old. For over a month I had been discussing reported rich lead-silver-copper properties in the Philippines with Thayer Lindsley and other officers of Panaminas. A competent and agreeable "Elderly" (not as old as I was) engineer named Ward Williams had talked with Thayer about high grade mines in a remote part of the

Jan 1, 1976

By Joe Keane

DOUG HALBE: The kickoff speaker, and my unanimous choice, is Joe Keane. Joe was born in Butte, Montana, and began his association with the mining industry as an under- ground miner at age 16. Currently he is president of KD Engineering and Metcon Research. He had it lucky when he went to school because there were only 44 elements in the periodic table, I understand. [laughter] Here's Joe. JOE KEANE: I'm doing this under protest. Maybe we can start the slides. Mr. Halbe gave me this topic, but I don't like it. I don't like Mr. Halbe either [laughter] because of the way he shanghaied me into this. He called me up on the phone and said this is what you're going to speak about: "Five Things I Never Want to See Again in Plant Design," and I said, "Huh!" Then I started getting stuff from SME about how to make a presentation. I have decided to change the title to "More Than Five Things I Never Want to See in Plant Design," since you can't have a completely negative speech; you have to have other topics. So we will have some other, not completely nonrelated, topics to sort of break the tension. I tried to find a joke to open with. I talked to Omar Mutati. All of his jokes were either about Bill Clinton, our beloved President, or they were too filthy to say in a mixed group. [laughter] So I decided to start this out with a profound statement. The pro- found statement is, "The meek shall inherit the earth, but not the mineral rights," [laughter] by J. Paul Getty. J. Paul Getty was one of my favorite guys because when a real obnoxious reporter asked him one day, "How can I become wealthy?" he said, "Drill for oil and find it."

Jan 1, 1998

By S. R. Dismukes

Mining is likely to be targeted by The United States Environmental Protection Agency (“EPA”) as one of its key enforcement targets for fiscal year 2002-2003. Identifying the mining industry as an enforcement target, coupled with an increase in enforcement activity in recent years, places each mining operation at increased risk of receiving enforcement attention. A properly developed and implemented Environmental Management System (“EMS”) tailored for your operation is invaluable in reducing the risk of incurring liability for non-compliance. At the heart of an effective EMS is an audit program that checks the company’s compliance with environmental requirements. In addition, audit privilege (in select states), voluntary self-disclosure, and the attorney-client privilege serve as very effective tools for managing those liabilities that may arise during auditing a well-developed program. Of course, these latter tools are effective only if the auditing program is properly structured and properly managed. EPA and some states also provide varying degrees of immunity for environmental violations that are voluntarily disclosed in writing by the company. However, self-disclosure laws and policies typically prescribe stringent requirements for parties seeking to take advantage of them. For example: U.S. EPA has recently extended the time period in which to provide full written self-disclosure to 21 days. However, U.S. EPA’s revised Self-Disclosure guidance also addresses when a company obtains knowledge of a violation for purposes of triggering the 21-day clock and specifically extends the knowledge requirement to include the company’s agents and consultants. This expansion increases the difficulty companies may have in clearly defining and managing when they obtained knowledge. This difficulty increases the importance of managing factual development and the strategic use of other

Jan 1, 2001

By R. L. Derick

On a regular basis, mine personnel should obtain air samples directly from active underground areas as well as remotely from sealed locations. These samples provide mine officials with data relative to the makeup of the various atmospheres. Should conditions underground change, these results can provide a baseline that can assist officials in determining the extent of change. Relating the concentrations of individual gases to time, applying gases to equations, and examining their change over time are tools that have been successfully used to determine if a heating event exists and, if so, the extent of the emergency. These atmospheric status equations have either been developed for the mining industry or adapted from other industries. They serve as tools to assist personnel in determining the condition of underground mine atmospheres. As long as the problem area continues to be ventilated, certain gases, gas ratios, and equations can be used to determine if a fire exists, what type of material could be burning, and what quantity of coal is burning. Once the mine or the involved section has been temporarily sealed, gases, ratios, and gas-derived equations can assist personnel in determining how conditions within the sealed volume are changing over time. To alleviate potential explosions when fresh air is once again introduced into the sealed volume, equations and a diagram have been developed to predict the likelihood of an explosive atmosphere. Similarly, prior to commencing recovery of a mine or section, equations exist that can assist in determining if the fire will rekindle when air is reintroduced. This paper serves as an overview to remind and/or instruct readers about gas-sampling methodologies and gas analyses to assist in determining the status of underground atmospheres.

Jan 1, 2006

By G. T. Lineberry, L. Adler

Due to safety-imposed constraints on clearances for mobile bulk handling equipment, it is necessary to optimally select a unit based on speed and size. The unit cannot be both large and fast. Since output is proportional to both size (or capacity) and speed, the combination must be carefully examined to maximize output. A simple graphical procedure and a calculus-based solution are presented to accomplish this. While the procedure applies to all mobile bulk handlers, as an example of the solution technique, attention is focused on shuttle cars. Background Major variables To fully define a bulk handling problem, the conditions, equipment, and activities must be characterized. The conditions and activities, when lumped together, are termed "encumbered space," since they "act to impede motion, as with a burden" (Lineberry, 1979). The insertion of mobile bulk handling equipment into what is already a difficult set of conditions and activities compounds the state of encumbrance, as limited space is competed for by many normal and life support systems. Long (1972) recognized the effects of design criteria, including road width, on haulage vehicle speed and, therefore, on production. Velocity -clearance curves Velocity-clearance curves are either available or can be constructed in the field. A preliminary set of curves for average conditions and activities is shown in Fig. 1, where clearances are only for the side of the vehicle (Lineberry and Adler, 1984). These curves set the safe speed limits for a vehicle operating at given clearances, under given conditions and activities. When feasible, velocity-clearance curves should be constructed through field measurement and observation. Curve construction should also consider haulway roughness, distances, and operator skill, as well as loading and dumping characteristics. It should be noted that haulage capacity determination is a total systems problem, not one just dependent on velocity and clearances. Production requirements and company capabilities also influence capacity determination.

Jan 10, 1985

By D. Noon

Mine production crews and drill-and-blast crews may be exposed to unexpected movement of ground when working under pit slopes. Without specialist geotechnical advice and appropriate measurement systems, mine crews are faced with conducting risk assessments and relying on subsequent controls that may or may not be adequate to ensure their safety. Mine crews need an ?early warning? monitoring system to give them the confidence that they will have time to walk out of the danger zone if the pit slope begins to move. Slope stability radar technology is used by mine geotechnical engineers to assess overall slope stability over an extended period, typically days or weeks, and to critically monitor slopes that are actively moving and may become unsafe. The complexity of slope stability radar allows for geotechnical engineers to assess movement types and movement rates across multiple work areas of a mine from long ranges, with alarm capability to a central location. However there are many mine work areas where production and drill-and blast crews are not adequately covered or alarmed by slope stability radar systems. What is required is an easy-to-use, short-range, fast-scanning tool that can be operated directly by a work crew and can provide a local alarm with sufficient warning when a wall movement occurs within the work area. The Work Area Monitor (WAM) concept has been developed specifically to be operated by a mine production crew. The system comprises a sensitive, fast-scanning radar coupled with a high-resolution camera, built into a mine-standard light vehicle. The system has been designed specifically for ease of use with the output being a local area alarm to warn workers of slope movement in their vicinity, as opposed to the broader pit monitoring and long-term deformation measurements of the known slope stability radar systems.

Jan 1, 2012

By I. S. Parrish

One of the most common errors uncovered while performing a reserve, or resource, audit is not in the geological modeling or grade problems due to poor sampling, prepartion or assaying. The error most commonly found is in tonnage or, more specifically, in the tonnage factor - that factor applied to volume to derive tonnage. Tonnage factors In the metric system, the tonnage factor is the density, or specific gravity. Specific gravity (Sp.g.) is defined by Dana (1947): • "The specific gravity of a mineral is the ratio of its density to that of water at 4° C (39.2° F). • "Density is the mass of the unit volume or weight of the body divided by the weight of an equal volume of water." When Sp.g. is multiplied by the metric volume it yields metric tonnes. In the English system, the tonnage factor is usually expressed in cubic feet per short ton (cu ft/st). When the volume in cubic feet is divided by cu ft/st, the resulting figure is in English short tons. Table 1 gives the cu ft/st factors equivalent to specific gravities from 1.6 Sp.g. to 5.8 Sp.g. The table is based on the following equation: cu ft/st = 0.9072 divided by Sp.g. times 0.02832 The blase attitude that most geologists have toward tonnage factors is echoed in the prevailing definitions of Reserves and Ore, as provided by the US Securities and Exchange Commission (S.C Form S-18), Canadian National Policy 2A and the SME Proposal for Reporting Terminology (SME February 1991). In each case, it is stated that "quantity" (SEC, SME), or "tonnage" (Can.2A), "is computed from dimensions revealed in...." etc. Unfortunately, "dimensions" do not directly yield tonnage. Dimensions must be factored by density to derive tonnage.

Jan 1, 1993

By Joachim Klein, Frank Reimann

Nodular-graphite cast iron (GGG) is a material similar to steel, and one which exhibits excellent properties, in particular for components exposed to pressure. GGG cast iron has been used in many cases when sinking mine shafts with conventional tubbing. With linings made of cast iron tubbings (the backfill concrete is not integrated into the calculations, and merely serves as bedding) the properties of the cast iron can be made full use of, provided the tubbing is made to the appropriate cross-section. Calculations have shown that better static values can be arrived at when using cross-sections other than those of tubbings made to conventional German standard. The cross-sectional design of the new types of shaft lining made from GGG is to be developed on these lines irrespective of the cast iron structure being only stressed component or its restistance function being combined with the one of concrete. GGG 50 is used for the first time to make the reinforcing inner liner of a main shaft currently sunk in Germany. The physical properties of nodular-graphite cast iron, strength and deformability, suggest that, in the future, its application will not be restricted to shaft support but also in tunneling. New moulding techniques with better three-dimensional modelling resulted in new tubbing designs as installed e.g. for the Hannover underground at present. Shield-driven tunnels have to withstand earth and water pressure, apart from axial machine loads. In this field time is money as well. Therefore easy handling and quick installation are necessary for successful, use. Last but not least, safety is of first-order importance for work in shaft sinking and tunneling. Cast iron lining systems, accordingly, are adequate systems, in particular for excavations underneath water for transport systems and for goods and passengers.

Jan 1, 1987

By Antonio Nieto

According to the analysis of surface powered haulage accidents involving off-highway haul trucks in openpit mining, the U.S. Mine Safety and Health Administration (MSHA), reported 1,300 fatal accidents from 1990 to 2005. Of these, 163 were considered off-highway truck haulage accidents, and at least 23 involved collisions of an off-highway truck with a neighboring vehicle or a worker on foot (Nieto and Dagdelen, 2006). In general, an average of 18 nonfatal accidents and three fatal accidents occurred in openpit mining per year when equipment backed over the edge of an embankment, stockpile or dump point (Fessak, et al., 2003). The specific problems that need to be solved can be determined by carefully studying the accidents involving haulage trucks (Marrara, et al., 2004). Solutions to haulage truck safety must consider the human factors affecting each task even when engineering solutions seem most appropriate. In surface haulage, human performance becomes a critical issue because of the unusual demand the vehicle?s places on their human operators: ? Roadways and working areas change frequently in mining operations. ? The sheer mass of mining equipment such as trucks requires control inputs (e.g., braking) far in advance of the desired action. ? Rough roads, loading and unloading impacts can subject the driver to dangerous shocks and vibration. ? Visibility is sharply curtailed by the bulk of the vehicle generating large blind spots. All of the above issues can be attributed partially to the lack of visibility (Pyles et al., 2003). Driver visibility and communications are key issues to reduce mining truck accidents. Analysis of fatalities and injuries involving mining equipment demonstrates the need to develop new intervention and control strategies to mitigate the risks associated with mining equipment operation. Ongoing development of these and other new strategies is required to achieve a reduction of injury in the mining industry

Jan 2, 2010

By Rodrigo Peroni, Euler Victoria

Knowing the depth of contacts between weathering zones in phosphate mines is determinant to define the stripping ratios and the mineralized zones. Contacts are gradational and difficult to define even in the drillhole samples, so the combination with geostatistical simulation techniques helps to define the contact zone and the grade distribution, providing a way to assess the probability of the occurrence and the positioning of contacts between the barren waste and the ore zones. These inputs are used in the scheduling, anticipating risks associated with mine planning scenarios. The results from an application to a case study showed a good improvement when compared to traditional techniques.

Jun 25, 2023

By C. Webb, M. A. Tuck

This paper describes the application of a cable disc elevator to continuous lift ore vertically from underground mines. Application of this system requires the tensions developed within the cable must remain within the carrying capacity of the cable including applicable safety margins. A critical element occurs at starting the system when it is fully loaded which requires the force developed by the system to exceed the static friction forces. This paper describes the laboratory rig developed to investigate the static friction forces. Details of the results of tests on three different ores for both dry and wet conditions are given. These results are discussed.

Nov 19, 2020

By Muhammad I. Kabir

The streamline method of recovery prediction reduces a two-dimensional problem to a bundle of one-dimensional ones. This paper presents the development and application of a novel scaling technique which, when used with a streamline model, causes s bundle of one-dimensional problems to further reduce to a single one-dimensional calculation. The one-dimensional calculation accounts for chemical-rock interactions and the streamline model for areal sweep. The scaling technique significantly reduces computation time, is readily modified to desk-top calculations, and can be applied to both absorbing and reacting species. The work was sponsored by the Interior Department's Bureau of Mines.

Jan 1, 1984

By J. L. Hoover, P. W. Conrad, J. Downey, S. Parrow, S. Rosenthal

The goal of the drill bit consumption study was to develop an equation(s) based on various components that affect drill bit wear and use that equation(s) to estimate the consumption of bits during production drilling. Drill bit data from various geographic locations were compiled and used to develop linear regression equations using the Microsoft Excel software package. Multiple drill bit consumption equations were developed and statistical analysis was used to verify the accuracy of those equations. The equations will allow mining companies to more accurately forecast drill bit consumption when evaluating new mine properties. This capability becomes increasingly beneficial to forecasting as the cost of consumables increases.

Jan 1, 2012

By Kenneth P. Neumann

The development of the Cyprus Thompson Creek Molybdenum Deposit near Challis, Idaho, began in 1967 when the first mining claims were staked on the intrusive rock outcrop. Exploration drilling continued for the next 14 years. During 1978, a decision was made to develop the deposit. In December, 1980, approval of the Environmental Impact Statement was received and construction of facilities and waste rock removal began. By the middle of 1983, 126 M metric tons of rock had been removed and all facilities were completed. The high work ethic of Cyprus Thompson Creek employees combined with innovation has made the mine one of the most efficient in the United States today.

Jan 1, 1983

By S. G. Britton

Thin seam mining presents unique challenges when management or economic conditions require significant productivity increases. These challenges are increased depending upon the presence of various external factors such as labor unions, Federal and state regulations, and market characteristics. This paper explores the turn-around situation occurring at Tanoma Mining Company (TMC), a medium-sized underground coal mining company in central Pennsylvania, USA. Using a systematic approach of improving management controls and direction, labor relations, and communications, coupled with an intensive upgrade/rebuild/replacement program for equipment and systems used at the mine, TMC has begun reversing its' cashflow position from negative to positive within two years.

Jan 1, 1991