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By B. K. McMahon

Block caving is an efficient mass-production method for the underground mining of large orebodies. However, the block-caving method requires a substantial investment in developmental works, based on the assumption that the rock will cave. Efficient block caving is prevented if the rock forms stable arches or breaks into fragments that are too large to pass easily through the finger raises. Under these conditions, the cost of the additional labor, drilling, and blasting required to assist caving may be sufficient to make marginal orebodies uneconomic or alternative mining methods more attractive. Reliable methods for the prediction of the block-caving behavior of an orebody are clearly needed at the initial planning stage. These methods should be capable of considering both geological and engineering aspects of a block cave, as experience has shown that the manner in which a block cave is initiated and developed may be almost as important as the geological conditions such as the nature of the rock material, degree of alteration, characteristics of the joints and faults, etc. The initial state of stress in the rock mass should also be considered.

Jan 1, 1969

By Paul A. Gerding

PURPOSE: Presentation to Society of Mining Engineers, Technical Session, Wednesday, February 19, 1958 - 2:00 P.M. General Industral Minerals - Penn Top South The silica industry is relatively small and in general is made up of small plants located near the consumer. In the United States there are approximately 155 established operating plants located in 37 states, extending from coast to coast. Silica, in varying degrees of chemical purity, enjoys a very diversified market. Silica is the basic ingredient of glass, bothcontainer and flat glass, and is used for grinding and polishing of flat glass up to the final polishing stages where rouge is generally used. Silica is used for foundry molds and cores, sandblasting, stone cutting, refractories, placing sand in furances, glass coatings and linings, laboratory glassware, construction, oil well fracturing for increased oil flow, filtering purposes, silicate of soda, silicon carbide, and others.

Jan 1, 1958

By Alexander Sutulov

It is calculated that since the beginning of last century, which practically coincides with the beginning of the Industrial Revolution, our civilization has consumed around 239.5 million tons of copper (see: Table 1). According to the most pessimistic projections of today, with only a 2.5% annual growth rate in demand, we are bound until the end of this century to consume another 200 million tons of copper in remaining 17 years. A recent study made by US Bureau of Mines (1) indicates that the proven ore reserves of 150 major operating mines and about 120 deposits sufficiently explored for development and feasibility studies accumulate a total mass of 49.3 billion tons of ore, assaying an average of 0.82% Cu and containing around 324 million tons of recoverable copper. Consequently, there is a high grade of probability that the bulk of our future ore supplies, for our demand of, say, next 25 years will cane precisely from these mines. The interesting point in USBM study is that it indicates the recoverable byproduct content of these ores and which is: 118.2 million troy ounces of gold 2277.4 million troy ounces of silver 7.1 million tons of lead 24.7 million tons of zinc 1.3 million tons of nickel 3.1 million tons of molybdenum 765 thousand tons of cobalt, and 720 thousand troy ounces of platinum. This information gives us a relatively reliable profile of our future ores for next 25 years, and thus makes possible evaluation of byproduct credits in our future copper mining and producing activities.

Jan 1, 1983

By Kevin Sierra, Orfelinda Avalo, Julio Guizado, Edwilde Yoplac, David Martinez

Mining tailings are slurry byproducts of mineral recovery. They generate serious environmental risks due to their toxicity when exposed to water and oxygen. Studies focus on eco-friendly alternatives for mitigating these environmental impacts. Processing these tailings enables a sustainable mineral production model through circular economy practices. This study evaluates using gold mining tailings to recover gold and produce bricks. Flotation tests obtained a concentrate with 86.66% gold recovery, containing sulfides (pyrite, arsenopyrite) and a tailing with silicates and oxides suitable for brick manufacturing and ornamental pieces. This approach promotes eco-friendly solutions and a greener approach to mining operations.

Feb 1, 2024

By Peijian Zhang, Yansheng Liu, Yuusaku Tominaga

The directions for ventilation control are often given in linguistic styles such as "if the airflow rate measured is small, a high value of rotation on a local fan should be chosen." In order to control the underground climate using a computer instead of a human being, both the reliability of data values measured underground and the application of human recognition of data values are required. The efficiency of data transmission is dependent on a method of checking a signal which is changed by mixing noises resulting from cases of electrical and mechanical damage to cables. In the study, fuzzy reasoning is adopted to choose a checking method for underground conditions from a normally operating state to an emergency. Fuzzy reasoning is applied to control airflow rate under the linguistic control rules given. It is shown that an effective series of linguistic control rules derived by fuzzy-sets theory is available in ventilation control when used in conjunction with an air velocity sensor, a computer and a local fan with thyristor control. Moreover, a system to make an optimum series of linguistic control rules for ventilation control is introduced.

Jan 1, 1987

By Sheldon P. Wimpfen

Under the Wilderness Act of 1964 and the accompanying House Conference Report, the Geological Survey and Bureau of Mines are charged with the responsibility of making recurring mineral studies of wilderness and wilderness candidate areas in national forests within and proposed for the National Wilderness Preservation System. The Wilderness Act, a major shift from the multiple-use concept of national forests, identified for the first time the value of mineral resource information in decisions for single-use designation of public lands. This concept was further realized when the Secretary of the Interior in May 1974 recommended that mineral studies be made prior to wilderness recommendations for five large Interior-managed game ranges and the Glacier Bay National Monument aggregating 7.8 million acres. Presently, our studies have been completed on 126 wilderness and proposed wilderness areas totaling 15.4 million acres in the national forests. In 1973, 1 year in advance of the act's 10-year review deadline, we completed the 34 primitive areas, originally the only potential additions considered by the 1964 Act.

Jan 1, 1975

By J. D. Grace

[Screening by centrifugal force is an unique, subject, for with the exception of only one vibrating screen presently on the market, all vibrating screens depend upon, gravity to pass material through a sizing mesh or screen cloth. This one screen that sizes by centrifugal force and utilizes gravity only to convey materiel along the screen, is the SYMONS V-Screen. This screen was designed by Loren Symons, a member of the family that has contributed so much to the metallic and non-metallic mineral processing industries. Among Symons' other outstanding contribution to these industries are the original Cone Crusher which revolutionized reduction crushing practice, the first high-speed horizontal vibrating screen, the original Rod Deck Screen, and one of the earliest vibrating Bar Grizzlies.]

Jan 1, 1965

By A. T. Yu

Technology and economies of scale have, in the past decade, brought about the emergence of giant vessels. Meanwhile, to answer the need for rapid dispatch, as a means of combating the proportionately far greater demurrage charges, shiploading and unloading speeds have soared (Ref. 1, 2, 3). As the loading and unloading rates have dramatically increased, so has the cloud of dust grown in unbearable proportions. It not only has threatened to be a real menace to machinery and men, but in certain instances has also seriously jeopardized fish and marine life (Ref. 4). In an era when ecology is king, dust in shiploading and unloading can no longer be shrugged off as a mere public nuisance, and its control is now duly recognized as of grave concern to all. Even if public outcry were not a problem, from the operator's own parochial point of view, dust can adversely affect productivity and the well-being of the operating personnel. Without adequate control, it can also result in costly equipment maintenance, particularly when the dust is micronic in size, and abrasive. The Hierarchy of Control Techniques Given the great fortune of not yet having to deal with gas and odors, in the jargon of pollution control, our problem is confined to having to control "particulates" only. To deal with "particulates", the myriad of dust control techniques can be utterly confusing to those who are not entirely well versed in the methodology. Our analysis of what is available to date results in the following hierarchy of logical preferences: 1. Prevention 2. Removal 3. Suppression 4. Containment 5. Dilution Since it deals with the root cause, prevention always outranks the cure. Once the dust is generated, removal nips it in the bud. Only when dust removal is

Jan 1, 1972

By Musa I. Marto

The theory of ore flotation has developed at a rather fast rate and the application of theory to practice has been successfully investigated. Significant technological advances have been made in such areas as control of the ore grade, automation in metallurgical control through conductivity measurements, and the development of faster and continuous analytical techniques for ore pulp analysis. Further significant improvements in mill control are being_ investigated through the application of a computer control to the process. This represents the more advanced trend in process control. At the heart of a control system installation, the digital computer will communicate directly with process instrumentation, perform' complex calcu¬lations to determine on a timely basis the control settings for attaining optimum results and automatically furnish signals to effect control actions. The process is considered as an integrated unit and economic criteria are used to measure its performance. The approaches to a mathematical model development to describe the process, optimization and control schemes as applied to an ore beneficiation process will be discussed.

Jan 1, 1962

By David C. Grant

During in situ uranium mining using ammonium bicarbonate lixiviant, the ammonium exchanges with cations on the ore's clay. Mter mining is complete, the ammonium may desorb into post-leach ground water. For the particular ore studied, other chemicals (i.e., uranium and selenium) which are mobilized during the leach process, have also been found in the post-leach ground water. Laboratory column tests, used to simulate the leaching process, have shown that aluminum chloride can rapidly remove ammonium from the ore and thus greatly reduce the subsequent ammonium leakage level into ground water. The aluminum chloride has also been found to reduce the leakage levels of uranium and selenium. In addition, the aluminum chloride treatment produces a rapid improvement in permeability.

Jan 1, 1982

By W. Dan Hausel

In previous reports by Hausel et. al., (1979 a, b, and c), Leighton and McCallum (1979), and McCallum (1974;1979), several exploration procedures were examined as to their effectiveness in locating kimberlite intrusives in northern Colorado and southeastern Wyoming, where approximately 90 kimberlites have been recognized within 5 districts (Figure I). Briefly, geological mapping and stream sediment sampling for indic- ative heavy minerals of kimberlite (pyrope garnet, chrome diopside, and magnesian ilmenite) proved to be the two most effective methods in isolating kimberlite occurrences within the granitic terrain of Colorado and Wyoming (Hausel et. al., 1979 a, b, and c; Leighton and McCallum, 1979). Where a kimberlite intrusive is deeply weathered, remote sensing using color and color infrared aerial photography may be a potential reconnaissance tool in kimberlite exploration. The kimberlitic eluvium supports thicker grassy vegetation, and at least one species of grass (the Bluebunch Wheatgrass) is found to grow only within the eluvium. The result is that vegetation in the kimberlitic eluvium is a better infrared reflector than the vegetation in the surrounding granitic soils (Hausel et. al., 1979 b; McCallum, 1974

Jan 1, 1980

By S. Upadhyay, A. M. Afrapoli

"Fluctuation in market price of mineral products has enforced mining companies to cut down their operating costs. One useful way of reducing operating costs in mining operations is to make optimal operational decisions, incorporating efficient mining fleet management systems (FMS). Over the last 50 years, several types of FMS have been developed and introduced in the mining systems around the world. However, there are two major shortcomings in existing systems. Firstly, none of the existing systems consider effects of the short-term plan on dynamic truck assignment. Secondly, most of the existing FMSs make decisions in a way that optimize a specific objective while ignoring others. Herein, we propose a multi stage and multi objective FMS that deals with aforementioned shortcomings of the currently available systems. The developed FMS, in its upper stage, links semi-dynamic operational decision making process to the short-term production plan by simultaneously assigning shovels to mining faces and allocating trucks to the shovels by implementing its first multi objective decision making model. Then in its second stage, in a real time dynamic decision making process, it assigns trucks to shovels and corresponding destinations by optimizing its second multi objective decision making model. The developed fleet management system has been verified using an Iron ore case study and the results are presented in this paper. INTRODUCTION Open pit mining method is the most common method to mine mineral from the earth. Based on Wetherelt and van der Wielen (2011) there exist 2500 open pit metal mines that are categorized as industrial scale mines. Over all of those, the amount of material handled using truck and shovel material handling system is more than the amount handled by all other systems together (Humphrey & Wagner, 2011).It has been proven by several studies that more than 50 percent of operating cost in a truck and shovel based open pit mining operation is accounted for material handling (Moradi Afrapoli & Askari-Nasab, 2017, Alarie & Gamache, 2002, Ahangaran et al., 2012). Thus, introducing even 1 to 2 percent cut in its material handling cost saves huge amount of money for the stakeholders. Over the last 50 years, two major areas have been identified to cut this cost. On one hand mining industries have been implementing equipment with higher production capacities, and on the other hand, researchers have been developing operations research techniques to make dynamic decisions as close to optimal as possible to deduct operational costs in truck and shovel based mining operations."

Jan 1, 2018

By Jamal Rostami

With the recent technological advances; Tunnel Boring Machines (TBM) have become a viable economic alternative to drill and blast in hard rock excavation. These machines are finding increasing use in underground mine development due to the potential benefits they offer. The successful application of TBM technology to mining depends on the selection of the most suitable equipment and cutting tools for the rock and ground conditions to be encountered. In addition to required testing and geotechnical investigations, cutterhead design optimization is an integral part of the machine selection to assure a successful application of the machines in a specific project. This paper presents and discusses the back-ground of TBM application in a mining environment and the lessons learned, the process of conducting site investigation and the necessary laboratory testing together with machine selection and performance estimation for TBM use III mine development.

Jan 1, 1997

By Paul Nicholas, Raju Gottumukkala

"India’s economy is expanding with rapid urbanization. Improvement in infrastructure is a keystone to the Indian government’s economic plans, including expansion of transit systems. Most of these systems are designed with elevated and underground sections. New Delhi, a city of 23 million people, suffers from heavy traffic congestion and pollution. The transit (metro) system is seen to be of critical importance. Phase 3 of the Delhi transit system project is 140 kilometers (km), with 40 km of twin-bore tunnels requiring 35 tunnel boring machines (TBMs) for construction. Transit systems are also under design or construction in Chennai, Bangalore, Kolkata, Hyderabad, Jaipur and Mumbai. Most have twin-bore tunnels. At present, 55 TBMs are operating on underground metro construction, and future projects will increase this number. This paper highlights the unique challenges of construction of underground metro systems in highly congested urban environments, using Kolkata and Delhi systems as examples. INTRODUCTION The first transit system in India was constructed in Kolkata (India’s third-largest city by population.) This line is 28 kilometers (km) in length, has underground and at-grade sections, was built in phases, runs north/south, and has 24 stations. This project was sanctioned in 1972, started construction in 1984, and was completed in 1995. The tunnels were constructed primarily by cut and cover methods with some open-face, compressed air shield tunneling. In 2006, the urban transport policy recommended construction of transit rail systems in all urban cities with a population exceeding 2 million. Further, in 2014 the central government stated that it would assist in financing transit systems in all cities with a population of over 1 million. In 2015, the central government approved the development of transit systems in 50 additional cities across India with a budget of $75 billion (see Figure 1). Transit development is just part of a huge expansion in planned rapid transport systems, which include metro, bus, high-speed rail, and monorail systems. Metro systems will include elevated and underground sections with twin-bore tunnels and underground stations. In the Delhi/National Capital Region (NCR), now the largest city in India by population, Delhi Metro Rail Corp (DMRC) was formed in 1995 as a joint venture company between the central government and Delhi state. DMRC operates the Delhi metro system. (see the case studies described later in this paper). DMRC has developed an external function to carry out studies and to offer consultancy to other cities planning transits. Since its inception, DMRC has produced Detailed Project Reports (DPRs) for every metro and monorail project in India. In 2012, DMRC became a partner in the management consultancy for Jakarta Mass Rapid Transit System, its first project overseas. DMRC became a model organization for other cities to follow. These cities have included Chennai, Hyderabad, Kolkata, Bangalore, Jaipur, Mumbai, Ahmedabad, and Nagpur. Other cities (e.g., Lucknow and Patna) are in the metro planning phase. Metro systems are under construction or partially operating in Hyderabad, Bangalore, and Jaipur."

Jan 1, 2016

By D. C. Martin

Construction of the Cerro Colorado on-off leach pad in northern Chile required placement of approximately 3,000,000m3 of fill over a P1an area of approximately 600,000m in irregular terrain with relief of up to 40m. Earthwork construction was completed in approximately six months using mine waste which was placed in 4 to 6m lifts using mine haul trucks. The lift thickness was reduced and the compactive effort increased in the upper 10m to enable development of a mat and additional resistance to possible differential settlements under dynamic (earthquake) conditions. A single 80 mil (2mm) HOPE liner was used below the leach pads and this was protected from the loading and unloading equipment using an engineered liner system consisting of screened sand, gravel and silt from local sources as the bedding and cover layers, and a heel of screened gravel and primary crushed low grade ore. Settlement monitoring, field testing and subsequent assessments of liner performance have indicated an adequate design was achieved and the project proceeded with considerable savings in time and construction costs.

Jan 1, 1995

By M. Hepokoski, M. Klein, L. Yan

"NIOSH research has shown that heat/humidity buildup is a major concern within coal mine refuge alternatives (RAs). These high temperature and humidity levels inside an RA may expose occupants to heat stress. Due to the safety risks associated with testing using human subjects, NIOSH partnered with ThermoAnalytics to create detailed thermal simulation models of RAs with human occupants. The objective of this effort was to predict a miner’s core temperature response and moisture loss in environments that may be encountered in a coal mine RA. These parameters were studied across a range of temperatures and relative humidity values to determine if the current 95°F apparent temperature limit for RAs is reasonable. The results indicated that the 95°F apparent temperature limit is protective, provided that miners are supplied with sufficient water. The results also indicated that the body core temperature did not reach dangerous levels even at an apparent temperature of 130°F. However, the results show that moisture loss increases with apparent temperature. Therefore, if the apparent temperature limit were increased, the water provided in an RA would have to be increased to offset moisture loss. INTRODUCTION The purpose of this effort was to predict a miner’s core temperature and moisture loss (sweating and respiration) in environments that are likely to be encountered in a coal mine refuge alternative (RA). A range of temperatures and relative humidity were studied to determine whether the current 95°F Steadman apparent temperature (AT) limit and 2.25 quart/day water requirements for RAs as mandated by the Mine Safety and Health Administration (MSHA) are reasonable [1, 2]. The effects of metabolic heat rate (activity level), miner size (height and weight), and pose (sitting or lying) on core temperature and moisture loss were also studied. MODEL DESCRIPTION TAITherm thermal modeling software (ThermoAnalytics, Inc.) was used to simulate humans in RA-like environments within a range of temperature and relative humidity combinations. The TAITherm Human Thermal Model (HTM) predicts the dynamic thermal response of the simulated miners while accounting for clothing, human tissue thermal properties, and active thermoregulation. The following sections describe the HTM in more detail, the thermal model setup for this analysis, and core temperature and moisture loss metrics found in published literature. Human Thermal Model Overview The TAITherm human thermal model was used to simulate the heat generated by the shelter occupants, and to predict the miners’ skin and core temperatures along with their sweat evaporation rates. The thermoregulation model simulates the process by which the body attempts to maintain a constant core temperature by considering the effects of shivering, sweating, and changes in skin blood flow. This model calculates surface and deep tissue temperatures within the human body as described by a surface mesh."

Jan 1, 2017

By A. Torrance, M. G. Seo

Velocity of detonation (VOD) is an important variable when evaluating the performance of mine blasts. Typically, for a VOD measurement, individual probes have to be loaded into each blast hole that requires a measurement, which increases the loading time and is not representative of the whole blast. Experimental studies of electromagnetic pulse (EMP) from the detonation of explosive charges show that electric and magnetic field signals are observed when chemical explosions occur in the air, at the ground surface, and in the underground. EMP has the potential to evaluate VOD of the whole blast without impeding the loading process. Due to a variety of physical causes which make the electromagnetic effects complex, measuring EMP of the detonation of explosive charges has not been fully studied yet. Five different antennae were tested with explosives, which are commonly used in mining industry. Among the five antennae, aluminum and copper tape, and wire were successful to detect the EMP. INTRODUCTION The measurement of the velocity of detonation (VOD) helps in evaluating and comparing relative performance of explosives in mine blasts. A VOD of an explosive is usually predicted by empirical mathematical equations or measured in-hole by VOD meters. However, conventional methods to measure a VOD have constraints: only a limited number of holes can be measured because cost of consumables for such systems is very high, and systems only allow a certain number of holes to be measured. The measurement cables have to be placed into the holes prior to loading with explosives which means that preparing to take the measurement is time consuming and has to be well coordinated with the mine. In order to evaluate VOD for a whole blast, there is a possibility of using electromagnetic pulse (EMP) from the detonation of the explosives. As there are many parameters that affect the generated EMP from explosive charges, measuring EMP of the detonation of explosive charges has not been fully studied yet. Most studies conducted relate to military related explosives, not the ones frequently used in mining industry. This research has been performed to have a better understanding of EMP from the types of explosives which are commonly used in the mining industry. To discover a way to detect EMP efficiently, five different types of antennae have been studied in the air and in the underground blasting conditions: coil, monopole rod, log periodic, wire, and aluminum and copper tape. LITERATURE REVIEW Conventional methods of measuring VOD Over the years, demands for more accurate theoretical predictions and physical measurements of the effects of the explosives have increased. Especially when both demand and commodity price decline, mining companies are keen to understand the effectiveness of explosives since it has a direct relationship with fragmentation, which influences their production rate. Since the 1940s, various methods have been devised to determine VOD of explosives.

Jan 1, 2019

By T. McCallum, C. Cooper, B. Hutzler

"In copper solvent extraction, managing the quality of the organic phase is a key parameter to ensure optimal physical and metallurgical performance in the plant. Increased throughput as a result of declining ore grades coupled with advances in plant design and practice, resulting in reduced organic losses, has pushed the limits of the status quo with respect to organic quality. Clay treatment of plant and recovered organic at the optimal dosage is critical in maintaining quality, however, achieving the optimal dosage through existing filtration capacity and practice can be difficult. Cytec has developed a process aid that increases efficiency of existing filtration equipment that has been successfully implemented at two commercial SX operations. ACORGA® CB1000 enables higher dosages of clay while allowing for more efficient use of existing filtration capacity. This study analyzes results from commercial trials and demonstrates that improved organic quality and clarity is achievable through optimization of current treatment practices. INTRODUCTION Decreasing ore grades have prompted copper solvent extraction operations to raise PLS flow rates, increasing plant throughput to maintain production1. The ability to process higher flow rates through existing mixer-settlers historically came at the expense of increased entrainments2. However, advances in mixer-settler design, practices and improvements in organic recovery processes have enabled operations to maintain, and in some cases reduce organic losses while achieving higher flow rates through existing equipment. Based on the increased demand on the SX equipment and reduced losses (or more efficient recovery) maintenance of the circuit organic quality through efficient clay treatment is now more important than ever. This paper discusses common industry practices and related issues in organic clay treatment, and presents benefits achieved in commercial operations through the use of ACORGA® CB1000 Clay Binder. IMPROVEMENTS IN DESIGN AND PLANT PRACTICE Mixer-settler design has improved since the first commercial copper SX operation in the late 1960s. Advanced designs in mixer, settler, and settler internals have contributed to reductions in entrainments. For example, improved impeller designs have been reported to decrease organic in aqueous entrainment from the ‘old designs’ of 50-200 ppm3 to as low as 4 – 10 ppm confirmed via diluent and reagent consumptions . Similarly, operations are reporting a 20-50% decrease in reagent consumption when compared to the original design criteria3. Operations have optimized settler internals to increase coalescence and have improved settler operating practices which have been shown to reduce entrainments7. Comparison of the SX world operating data from 1999 and 2007 shows reductions in organic entrainment losses with increases in flow rates."

Jan 1, 2015

By M. Noppé

"Dilution in underground coal operations can be underestimated by up to five times during Feasibility Studies, with disastrous economic consequences. Every 1% of stone waste introduced can reduce an in situ specific energy of 11,000 BTU/lb (25 MJ/kg) by some 110 BTU/lb (0.25 MJ/kg) and increases the abrasiveness of the run-of-mine coal. Where a wash plant is not in place, penalties imposed for not meeting contractual specifications alone can amount to some AU$1 million per year.This paper presents a method for monitoring, reporting and ultimately controlling dilution in an underground coal mining operation. The dilution trends before and after introducing the recommended controls in a continuous miner/longwall mine are presented over an eight year period. The additional information from such a dilution monitoring program can also be used to control mining horizons and plan longwall extraction heights across the face proactively, on a short-term scale with resulting improvements in productivity. INTRODUCTION Grade control, as practiced on any mine, is concerned with predicting routine quality and tonnage values for short- to medium-term mining operations, and the reconciliation of these predictions against “actual” results. For a longwall mine supplying steam coal, such routine parameters may include the proximate analyses, specific energy (SE), abrasiveness and sulphur, as well as float and sink analyses if the coal is beneficiated. In addition, grade control is concerned with identifying the mineable horizon (or horizons) in a selective-mining operation, together with monitoring how well these horizons have been extracted or adhered to. Close-spaced surface drilling can be costly for any mining venture, particularly for longwall mines operating in the deeper seams. For this reason, much of the data for short-term grade control requirements are acquired during actual bord-and-pillar development. The underground data are derived from so-called “channel” samples. These samples are cut or chipped from the coal seam, perpendicular to the mining horizon, with dimensions suitable for obtaining sufficient “representative” sample for analyses. For a 2m thick mining horizon, a channel sample 300 mm wide and 50 mm deep over the thickness of the horizon would provide some 4.5 kg of sample, sufficient for most of the necessary tests. To allow the information to be computer recorded, additional information such as seam thickness, sample co-ordinates, and the elevation of the seam (or horizon) roof or floor, may be required."

Jan 1, 2015

By Yiming Sun, David Tsztoo, Rick Nolting, Adam M. Wirthlin, Rebecca Fusee

"Excavation and initial support of the New Irvington Tunnel presented significant challenges, including rapidly changing ground conditions, heavy ground loads, and squeezing. Such behaviors were anticipated from historic tunneling records of the adjacent Existing Irvington Tunnel, and extensive site investigation, but clearer understanding of their actual extent and causes has resulted from convergence measurements, observations of ground behavior, initial support monitoring and detailed geologic mapping. Time-dependent movements, documented hours to months after excavation in clay-rich rock and in moderately to intensely fractured rock, identified squeezing areas, allowed classification by currently-used predictive methods and added to the list of lessons learned in tunneling such ground. INTRODUCTION In March 2003 the San Francisco Public Utilities Commission (SFPUC) authorized funding for the $4.6 billion Water System Improvement Program (WSIP) to repair, replace, and seismically upgrade its water system. The program consists of 35 local projects located within San Francisco and 48 regional projects located in several counties from the Sierra foothills to the San Francisco Bay Area. The New Irvington Tunnel (NIT), a key component of the WSIP, is located east of Fremont in Alameda County, on the east side of San Francisco Bay. The NIT is a new 18,660 foot (5,689 m), redundant tunnel, 190 to 670 feet (58–204 m) offset from, and subparallel to the Existing Irvington Tunnel (EIT). Built between 1928 and 1932, the EIT was constructed with an unreinforced cast-in-place concrete lining and is vulnerable to damage in the event of a major earthquake along the two closest active faults. The Hayward Fault is located less than a mile west of the tunnel, and the Calaveras Fault is located half a mile east of the tunnel. Although the alignment does not intersect these faults, the shaking and sympathetic displacement along secondary faults that cross the tunnel alignment are potential hazards. The NIT provides a seismically reliable water transmission facility capable of withstanding earthquake damage and maintaining continuous water service after a major earthquake. The NIT also adds system redundancy and provides for operation flexibility of running water through both tunnels, or through one tunnel while the other is out of service for inspections and maintenance."

Jan 1, 2016