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By B. Campbell

This paper will detail the successful construction methods of a 20- foot diameter wet well shaft, approximately 180 feet deep in overall depth and 150-feet below the water table, adjacent to Lake Nacimiento, in San Luis Obispo County, California. In addition to this, highlights will include the selection process in determining the most economical support of excavation, while minimizing risk of large water inflows as indicated in the Owner?s Geotechnical Baseline Report (GBR).

Jan 1, 2010

By W. W. Roberts

Key elements to the successful excavation and support of the Forest Glen Station and Tunnels for the Washington Area Metropolitan Transit Authority are discussed. Excavations encompassed a twin-vault station; 2339.3 m (7675 feet) of conventional drill and shoot tunnel; and 810.8 m (2660 feet) of mixed faced tunnel. The use of dewatering, boom type continuous miner and shotcrete in the mixed faced tunnel, along with hydraulic drills, bolts, and shotcrete in the rock tunnels and station proved to be effective methods.

Jan 1, 1983

By D. R. Taylor, R. G. Goss

The use of clay granules as carriers for pesticides dates from the early 1940's and by the present day represents a business conservatively estimated at between 200 - 300 thousand tons / year in the U.S. alone. Aside from economic and specific target pest efficacy advantages, the use of clay granules as pesticide carriers also delivers a number of environmental benefits which will be reviewed. Topics to be discussed will include: 1) drift control (versus liquid sprays), 2) mobility (in the environment), 3) worker safety, and 4) transportation (spill) safety.

Jan 1, 1999

By Eugie Kabwe

The velocity of detonation (VOD) is a significant property considered when rating an explosive. It may be quantified as a confined or unconfined velocity. The confined velocity is the rate at which the detonation wave propagates through an explosive within a blast hole or any restrained space. The unconfined velocity emanates when an explosive is detonated in the open. However, the confined velocity is more significant as explosives are usually employed under a definite degree of confinement. This paper evaluates the increment of air deck volume and its effect on the VOD. The air gap (air deck) volume is increased stepwise from 10 to 30% of the total blast hole volume by reducing the stemming height in the collar zone. Thereafter, the VOD estimation in the 172-mm-diameter explosive column is conducted using the Dáutriche technique. It is observed that the VOD reduced with the increasing air deck volume and detonation failure is high when 30% of the blast hole volume is replaced with air deck. It is deduced that the increment of the air deck volume has an effect on the attenuation of the steady-state VOD.

By I. M. Eitani, M. Karmis

Ground control presents the most serious problem in underground thick seam mining. In addition to parameters such as depth thickness and inclination of the seam and nature of the coal and the immediate strata, the stress interactions caused by the mining sequence must be carefully evaluated and understood, if safety and productivity objectives are to be fulfilled. In this paper, the most widely-accepted thick seam coal mining methods are reviewed and suggestions are made for future work pertaining to ground control problems.

Jan 1, 1981

By Edward C. Dowling

Dilbert, management mumbo-jumbo, and human resource buzzwords aside, this paper defines corporate culture and why it is important to understand it. The sum of company experience, both good and bad, defines the way people work together. This integration of experience outlines the expected behaviors, or culture, in an organization. Given the competitive pressures inherent to our industry, the dizzying ongoing industry restructuring, and the recognition that behaviors drive effectiveness, the appreciation of an organization's culture is a prerequisite to meaningful improvement, particularly for those organizations undergoing growth, acquisitions, or mergers.

Jan 1, 2001

By A. John R. Hart

INTRODUCTION The use of precast concrete tunnel liners as the initial and final tunnel lining for transit systems has been a major consideration of designers for over three decades. The obvious benefit of building a tunnel that requires only a single pass in constructing the structural lining can provide the opportunity of saving both time and cost. This technique has had worldwide application in transit systems in London, Munich, Hong Kong, Toronto to name a few. In the United States precast liners were evaluated for use on the BART System in San Francisco in the early 1960's but did not provide sufficient confidence in the sealing capabilities available at that time. In 1976 it was decided to call for bids on the Lexington Market Tunnels in Baltimore with a precast concrete liner alternative for one of the tunnel drives. This option was selected by the owner and UMTA to provide a study evaluation for the benefit of the industry. HISTORY In 1983 Washington Metropolitan Area Transit Authority began calling for a series of bids on soft ground tunnels on the Green Line, which included the option of using precast concrete tunnel liners first as an alternative to fabricated steel tunnel liners. Over the years following, the precast concrete tunnel liners have become known as the conventional tunnelling system and, in the last year,

Jan 1, 1989

By Keiichi Fujita, Katsumoto Ueda, Hiroshi Nakauchi, Naohiko Okumura

INTRODUCTION This paper presents (1) modified slipform system which was employed for simultaneous concrete placement for permanent lining and Instruction of a partition wall in the execution of a ventilation shaft 620m deep, and (2) current shaft sinking techniques which have been applicable and efficient for the subsurface conditions in Japan. MODIFIED SLIPFORM SYSTEM FOR PERMANENT LINING OF VERTICAL SHAFT General Information This paragraph deals with rapid construction by using modified slipform system for the permanent concrete lining and a partition wall of ventilation shaft, which has inside diameter of 620m and depth of 620m, of Enasan Highway Tunnel. The general feature of the shaft is illustrated in Fig. 1 and standard section of the shaft is illustrated in Fig. 2. The geological condition surrounding the shaft is mainly of ryolite and surface is of talus, but as a whole, they are rather weak and weathered rocks with faults, fissures and clay seams. 220mm borehole for the geological investigation was used as a drainage hole, predicting the amount of water inflow into the shaft to be 10t/min. The shaft was executed mainly by means of the conventional short step sinking method of 1.2m lift, employing temporary headframe and hoists. For each lift, 40 to 50cm thick temporary concrete lining was used. About 28,600m3 of rocks were excavated and

Jan 1, 1979

By D. A. Robbins

Remote sensing for environmental measurements is already being used. Aircraft-mounted imaging spectroscopy has been used to evaluate historical mining operations, as well as active mine sites. To the extent that remote sensing can provide more sensitive, cost effective and timely monitoring potential, the technology is of interest to the industry. Questions, however, remain about the application and validation of the data and concerning the availability of the technology in the private sector. This paper discusses some of the potential uses, benefits and concerns related to remote sensing. And it discusses efforts to monitor the technology's development.

Jan 1, 2000

By Antonieta Middea, Rupen Adamian, Fernando F. Lins

This work presents the results obtained with aggregation of fine talc (-19 m), a naturally hydrophobic mineral, in the presence of KC1 solutions. The classical DLVO theory describes well the aggregation of talc in dilute KC1 solutions. Beyond 1 M KCI we have found indications that a non-DLVO interparticles force is operative, say an hydration (repulsive) force. This structural force could be responsible for the unexpected re-dispersion of talc suspension. However, no repulsive force (depression) has been observed in salt flotation of talc at higher ionic strength, up to 3 MKCI.

Jan 1, 1995

By J. G. Wargo

In situ leaching of disseminate gold deposits has been studied from a theoretical perspective to outline the operating environment for the process. Rock permeability and the relationship of permeability to the site of gold particle deposition are key factors in predicting the efficiency of in situ leaching. Permeability measurements, however, have rarely been made during gold exploration, so that secondary geologic features of the deposit must be used. This paper examines some of the geologic characteristics of disseminated gold deposits and comments on the problems and possibilities of in situ leaching of gold.

Jan 1, 1987

By Robert S. Ondrey, Robert A. Haney, David J. Atchison

The Mine Safety and Health Administration has conducted tests to determine the effectiveness of two methods for reducing diesel particulate emissions in underground coal mines. Both methods involved collection of the particulate material before being released into the environment. One method utilized a disposable pleated paper filter attached to the tail pipe; the other utilized a reusable wire mesh screen attached to the tail pipe. This paper describes the instrumentation and testing used to evaluate both control methods. Results of respirable dust and diesel particulate measurements made underground are presented and analyzed.

Jan 1, 1992

By B. Ollila, L. Brown

As mining fronts converge in sill pillar extraction, the mine seismic hazard can be significantly altered and large seismic events have been known to occur. This study used common seismological tools to analyze the extraction of highly stressed sills from two deep Canadian mines with the objective of characterizing the rock mass failure process and relation to large seismic events. The approach treated a sill pillar as a mine-scale failure process, meaning the temporal and spatial analysis scales needed to exist on a similar scale to a significant part of the mine. The temporal analysis scale overlapped with the entire mining sequence, included several years of data to establish long term change in the characteristics of rock mass failure. The spatial analysis scale included the rock mass surrounding a large part of the convergent mining sequence. To accommodate the large spatial and temporal scales, the highest magnitude 2% of events in the dataset were analyzed. Similar results were shown for sill pillars in both mines. Changes in event location, time, magnitude, energy index and apparent volume were similar to expected behavior of rock failure. Indications of strain hardening and strain softening were observed in the sills. The hardening period was characterized by a high rate of small events, high energy index and low apparent volume, giving an indication of high stress and low rock yield. The softening phase was characterized by a decrease in the rate of small events concurrent with an increase in the rate of large events, low energy index and high apparent volume, indicative of release of stress and increase in deformation. Large magnitude seismicity was strongly related to the softening phase, with several Nuttli magnitude 3.0+ events occurring shortly after the transition from hardening to softening failure regimes. Sill failure was indicated by consistently low EI and low levels of seismicity and seismic hazard in the sill pillar.

Apr 26, 2022

By Roger Beckie, Leslie Smith, Craig Nichol

To study the hydrogeological processes that control the movement of water through unsaturated waste rock, an intermediate-scale (8m x 8m x 5m) waste rock pile has been constructed and instrumented. The constructed pile is monitored for moisture content, matric suction, temperature, matrix water chemistry, gas chemistry, gas pressure, rainfall, evaporation, discharge volume and discharge chemistry. The pile is built upon a grid of 16 contiguous lysimeters. The experiment is designed to investigate the mechanisms that create rapid water flow through a pile and its exchange with slower-moving matrix water.

Jan 1, 2000

By V. A. Leach, Lokan. K. H., S. B. Solomon, R. S. O’Brien, L. J. Martin, K. N. Wise

INTRODUCTION The development during 1979 of a relatively small, but high grade (10,000 tonnes uranium at an average grade of 2 per cent), uranium ore body at Nabarlek in the Northern Territory, Australia offered an excellent opportunity to obtain detailed radiation data for an open cut mine operating during the dry season. The ore body (Queensland Mines Limited-1979), which was completely extracted in a period of four and a half months, consisted of a vein type deposit dipping at 30 to 45 degrees and contained a central core of pitchblende in massive and irregular pods, surrounded by lower grade fine grained disseminated pitchblende. Mineralisation extended from the surface to a depth of 72 metres over a length of 230 metres with an average but variable thickness of 1D metres. Ore near the surface had been heavily weathered and complex secondary minerals were formed which had dispersed from the main vein. Mining was carried out with large earth moving equipment. Overburden and weathered surface ore were removed initially with scrapers. At greater depths bulldozers were used to rip and assemble ore and rock at each level, and these were removed by large trucks to the ore and waste rock stockpiles. Where necessary, blasting took place during shift changes each evening. Mining was essentially continuous with two ten hour alternating shifts working for thirteen days out of fourteen. At the completion of mining a relatively small excavation (335m x 185m x 70m) remained, and this will serve as a tailings repository during the milling phase. FIELD MEASUREMENTS The inhalation of radon daughters, arising from the radioactive decay of radon gas is well established (Archer et. al. 1973) as a potential hazard in the uranium mining industry. Control over radon and its daughters to ensure that recommended exposure limits are not exceeded is achieved by providing adequate ventilation, and under normal circumstances natural ventilation from an open pit should be sufficient. However, during the dry season it is not uncommon for stable atmospheric conditions, with little horizontal air movement, to develop - particularly at night - and significant radon daughter concentrations may accumulate. Throughout the entire mining period measurements were therefore made of radon and radon daughter levels at representative locations within the pit and on the ore stockpile as it developed. Initially these measurements were carried out manually, using the Rolle method for radon daughters, (Rolle 1972) and .scintillation cells (Lucas 1964) or a two filter tube for the determination of radon (Thomas 1970). For the latter half of the period however, a continuous recording instrument, developed within the Laboratory was used to provide a detailed record of radon daughter levels within the pit. At the same time, continuous readings of wind speed and direction, and vertical temperature gradient between 10 and 3D metres were recorded on a 30 metre meteorological tower, situated 800 metres from the pit. Radon Emanation Rates It is evident that radon and radon daughter concentrations depend on the grade, or more particularly, on the surface radon emanation rate of the ore which is exposed. Accordingly, as the mine progressed, detailed measurements were made of both of these quantities. The surface emanation rate of radon was determined for each ore bench as it was exposed by placing an extended array of canisters, filled with freshly degassed activated charcoal, face down on the ore for a known time. These canisters, which had previously been calibrated in the Laboratory, adsorb radon with high efficiency, and the total radon adsorbed is measured after retrieval by detecting the gamma rays from the trapped radon daughters (Countess 1977). At the same time, as each canister was placed in position, a measurement of the local ore grade was made for each location. This was achieved with a calibrated sodium iodide scintillation detector, adjusted to detect the 609 keV gamma ray from the isotope 2148i, a decay product of radium. Finally, measurements were made of the radiation field 1 metre above the surface, with a gamma ray survey meter, which was calibrated in the Laboratory. The relationship between the scintillator count rate and ore grade was determined by comparing the scintillator output with the gamma monitor, and relating the latter measurements to ore grade (Thomson and Wilson 1980). It was observed that while emanation rates and ore grades varied widely, the ratio of emanation rate to ore grade was in general fairly stable. A plot of this ratio is presented as a function of depth below the original surface in Figure 1. For most observations the ratio is constant at a value of 80 Bq m-2 s -1 per unit ore grade, where ore grade is expressed as percentage of U308. At the surface however, where the ore was weathered, the ratio was about a factor of three higher, and at two particular depths, where high grade pitchblende was being removed, it was very much lower. This was not unexpected as earlier Laboratory studies of drill core samples from Nabarlek had indicated that the emanation coefficient (the fraction of radon produced within the ore which escapes from the mineral particles) decreases with increasing ore grade.

Jan 1, 1981

By Brij M. Moudgil, Ivan U. Vakarelski, Yakov I. Rabinovich

Polymer and surfactant dispersant are widely used to disperse filler particles within a medium. Sur- faces active dispersants form self-assemble structures at the solid-liquid interface. The mechanical properties of the surfactant structures have been determined to strongly influence the dispersion behavior. In this study the atomic force microscope (AFM) is used to determine the elastic modulus and yield strength of a steric dispersant layer adsorbed to a rigid non-deformable surface. To interpret these values a model for elastic body contact based on a modified Hertz theory is applied. The results from this method may aid in the design of application-based dispersant systems.

Jan 1, 2003

By Andy J. Robinson, Mark D. Claassen

Railroad companies and transit authorities have been slow to acknowledge that for many—utility crossings, a direct pipe installation below live rail can be just as effective as a more intrusive traditional cased crossing. Properly designed and specified pipe jacking work, and specifically pressure-balanced microtunneling, coupled with careful specification and analysis of geotechnical monitoring and, where necessary, ground improvement measures, can produce a low-risk, low ground movement solution to the needs of utility companies and municipalities whose services need to pass below urban and rural rail corridors. This paper discusses the design, geotechnical and ground improvement aspects of microtunnel crossings below active heavy and light rail lines and crossings beneath active subway tunnels.

Jan 1, 2003

By Norman D. Harte, George W. Holl

The development of the most important tool used in Site Testing is reviewed briefly and the application of the information gained is described. The operation of Site Testing and pregrouting of underground excavations is dealt with in detail. Practical experiences (and pitfalls into which the inexperienced might fall) are recorded. But for the application of Site Testing and grouting of shafts, tunnels and other excavations, vast areas of the present goldfields in South Africa would remain unexploitable.

Jan 1, 1981

By Malcolm J. McPherson

There have been numerous recorded cases of mine explosions being initiated by falls of roof. The actual mechanism of the ignition has often been unknown. One possibility is incendive frictional sparking, particularly when the falling rock contains quartz. Another possibility that has received little attention is the increase in temperature of the air due to adiabatic compression under the falling roof. This paper analyses that possibility and concludes that falls which are extensive in plan area but not necessarily of great thickness of falling rock can, indeed, produce temperatures in excess of those required for the ignition of coal dust or methane.

Jan 1, 1995

By G. Gaidajis

In this paper, a semi-qualitative methodology is presented and then applied to an aluminium extrusion industrial facility in order to perform an initial environmental assessment. The results of the assessment enable an improved understanding of the environmental performance of the facility and more importantly identify the areas of significant environmental concern. Following, the application of case-specific sustainability indicators related with the areas of significant environmental concern, leads to a more comprehensive sustainability assessment. The applied two-step approach offers a quick and reliable environmental assessment and help focusing on the most environmentally problematic areas. Moreover, the follow-up of the specific indicators seems to be appropriate for the improvement of the environmental performance of the examined industrial facility.

Jan 1, 2008