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By R. W. Brown, J. L. Loper

The process of sand erosion has been harnessed to perform a useful function—the directed perforating of oilfield tubular goods and formation rock. In this process the sand is carried by a liquid medium and the resrrlting slurry is forced through a nozzle at an extren~ely high velocity. Upon impingement against casing or formation, the fast-moving sand particles erode a perforalion in the casing followed by cavity formation in the medium behind the casing. The many factors influencing the rate and extent of this penetration are inherently difficult to establish experimentally. Equations describing submerged jet behavior have been applied to these conditions. The following paper develops the equations for predicting the performance of the perforating jet. INTRODUCTION The cutting power of high-velocity sand has been well known in the petroleum industry for many years. Sand carried by a high-velocity gas stream causes severe erosion. This effect has been the cause of numerous production problems in certain areas. It was logical to expect that this phenomenon would one day be adapted to useful industrial applications. Development of mobile, high-pressure, high-horsepower pumping equipment in the last decade has made this possible. The sand erosion process involves pumping a fluid containing abrasive solids through a set of nozzles at a high differential pressure (2,000 to 4,000 psi). The pressure conversion into kinetic energy imparts high velocity to the sand particles which, upon impact with the formation face or casing wall, erode the material in an organized pattern. This paper attempts to establish the effects of the various parameters and to predict the performance and limitations of the process. The following factors will be considered: nozzle differential pressure, perforation size, sand concentration, nozzle stand-off distance and backpressure. In general, this discussion is presented along theoretical lines and is substantiated by field results and data where reliable field data exists. POWER EQUATIONS The penetration rate of a high-velocity hydraulic jet is proportional to the power or energy of the jet at the point in quesion. The power of the submerged jet will decrease with distance (or penetration) into the cavity created by the jet. As the cavity is extended into the formation, the power of the jet diminishes to a value equal to the threshold cutting power of the particular formation which is defiined as the lowest power level at which the formation will be abraded by the jet. Obviously, when this point is reached, no further cutting of the formation can occur. It is assumed that this power level for a particular formation is a function of the hardness of that formation. The following equation can be written for the hydraulic process of formation abrasion.

By V. S. Tuman

In the first part of this paper, an estimate is made of the magnitude and extent of the thermal stresses which result from mud circulation. Our study is made for the period of relaxation, i.e., when the drilling operations are terminated and mud circulation is discontinued. In the second part, we have shown how the thermal stress can affect the wave propagation. An example is worked out for a Carbondale sandstone (Illinois basin). It is concluded that, in extreme cases when differential temperature is about 100°F, the travel time will be affected by about 2 microsec/ft. For more refined permeability studies, such corrections would be desirable. MAGNITUDE AND EXTENT OF THERMAL STRESSES RESULTING FROM MUD CIRCULATION When geological beds are penetrated by boreholes, it is observed that the formation temperatures increase with depth; however, the temperature profile varies considerably from place to place. During drilling operations, mud pumped from a pit at atmospheric temperature absorbs heat from the lower beds. As a result, the drilling fluid returning to the surface is at a higher temperature than the surrounding beds. The temperature gradient in a well depends on the rate of mud circulation and other factors; normally, this temperature gradient is smaller than the natural gradient in the formations. (See Fig. 1.) The temperature difference between the mud column and the surrounding beds gives rise to therma1 stresses (which are also important in the phenomenon of fracturing), and it is expected that they will affect the transit time of the sonic front in velocity logging.1 It is evident chat beds near the surface will undergo various cycles and will have a complicated dynamical and thermal-stress history. A limestone bed which is just penetrated will act as a source of heat, warming up the cold mud pumped down a few minutes earlier from the surface pit. The same limestone bed a week later will act as a sink, absorbing heat from the drilling mud which has already warmed up sufficiently to be at a higher temperature than the bed in question. No doubt a large section of the hole will undergo a heat treatment, which will make the calculation of the exact magnitude of the thermal stresses very difficult. In the solution of wellbore thermal equation, it is assumed that the rock around the wellbore is elastic and isotropic, and that the system is radially symmetrical. A complete dynamical solution of the thermal stresses set up at different horizons during the drilling operations would require a comprehensive history of the mud circulation, the surface temperature of the pit and the number of hours in which mud was not circulated. CONDUCTION OF HEAT AND THERMAL EQUATION OF STATE

By Watson D. F

Armstrong's (1983) criticisms of PhiIip and Watson's (1982b) note on optimal drilling patterns are based on misinterpretation, supported by errors in geometry. Furthermore, Armstrong argues conceptually from the perspective of Matheronian geostatistics, as does also Rudenno (1983a, b). Thus, both authors embrace a global, probabiIistic method of assessing spatial data sets, an approach that must be contrasted strongly with local, deterministic interpolation methods. Some of the important assumptions of geostatistics are outlined and the non-unique nature of the method discussed. A probabilistic approach can be judged appropriate when exploration data are erratic, or known to be unreliable, or when extrapolation is desired. Where data are treated as exact, kriging can give the most biased result if tested against other interpolation methods. We reiterate our previous conclusion that the equilateral triangular grid is approximately 30 per cent more efficient (in terms of numbers of drill holes) compared with a square grid for the same maximum interpolation distance. This is simply due to the improved isotropy of sampling. New, locally-based, deterministic methods for computing ore reserves seem to be required.

Jan 1, 1984

By Derek G. Cieplinski

Regenerative conveyors with complex conveyor profiles place unusually stringent demands on the starting drive control. Depending on the nature of the conveyor loading, the drive must either provide a positive driving force to overcome conveyor friction and gravitational forces if the belt is empty or the inclined sections are loaded, or it must provide a retarding force to resist the gravitational load of decline sections to control the acceleration rate. This paper discusses the requirements of regenerative conveyors, reviews the working principals of fluid couplings, and examines their interaction by means of a case study of a 1700 m long regenerative conveyor utilizing a fluid coupling with a proportional brake control to provide controlled starting and stopping under all load conditions.

Jan 1, 1993

By Laszlo Toth

A feeder is used to control the gravity flow of bulk solids from storage areas, like a bin or a stockpile. For this type of application, it is important to select a proper drive that can fulfill all of the demands put on it. High starting torque capacity, variable speed and the ability to handle frequent starts and stops are some of the demands that the drive must be able to meet. The following is a comparison of the most common type of drives used today for feeder applications. When a feeder is started, the breakaway torque may reach as high as200% of the running torque. The accelerating torque usually is set to protect the carrying element of the feeder, like the belt for the belt feeder and the carrying chain of the apron feeder (Fig. 1).

Jan 1, 2003

By Robert E. Fosse

Driven 14-inch-square concrete piles were used as the foundations of Genentech Hall at the new University of California, San Francisco Mission Bay Campus. The five-story, steel eccentrically-braced frame building is currently under construction at a 43-acre property located in a former large shallow marshy inlet from San Francisco Bay. The piles were driven through 10 to 25 feet of fill and 20 to 60 feet of soft compressible Bay Mud into an underlying dense sand layer. Pile design capacities were developed for traditional allowable stress design, load factor and resistance design, and ultimate design criteria. The ultimate level capacities were for checks of loads occurring when the links in the eccentrically-braced frame yield during an earthquake. A load test program was performed to confirm pile design recommendations. Two test pile locations were selected for compression, tension, and lateral load tests to evaluate pile capacity and pile/soil stiffness under long-term, short-term and rapid loading conditions. Maximum test loads were 1000 kips downward, 350 kips uplift and 50 kips lateral. Foundation construction began by driving 34 indicator piles with a Delmag D46-32 diesel hammer of 113 foot-kips maximum rated energy. All indicator piles were monitored during initial driving using the Pile Driving Analyzer. Restrike data, obtained several days after initial driving, indicated significant pile-soil setup and typical pile capacity increases from 750 to 1000 kips. The majority of the 1242 production piles were then driven to acceptance criteria of 75 blows per foot and a minimum embedment of 10 feet into the dense sand bearing layer. Piles driven to full length without achieving the blowcount criteria were evaluated on a case-by-case basis. Acceptance of these piles was established by evaluating restrike data.

Jan 1, 2002

By Satyajit Vaidya, Rudolph Frizzi, Sandy Larimer

"This paper presents a case history in design and construction of a deep foundation system that included high-capacity open-ended driven piles constructed to support a high-rise building in Manhattan, New York. The project site is bordered by existing buildings, active streets, and critical public transportation infrastructure, which were considered in the new building’s deep foundation and seismic design. This paper focuses on driven pile foundation design and installation through relatively loose soil deposits. Unique design aspects included seismic design considerations, and pile splice design for open-ended steel pipe piles subject to significant uplift and lateral loading. Unique construction aspects included quality assurance of open-ended steel pipe pile splices, and uplift and lateral load testing of driven piles installed in close proximity to other foundation elements installed for the project.SITE CONDITIONS AND SUBSURFACE CONDITIONSThe project site is located in Manhattan, New York, and is bordered by existing buildings, active streets, and critical public transportation infrastructure that is located about 60 feet from the site. The existing sidewalk grades around the site are between about el 4 and about el 13; elevations are referenced to the North American Vertical Datum 1988 (NAVD88).Subsurface conditions at the site generally consist of successive strata of historic fill, former river bottom deposits consisting of compressible clayey soils, and medium dense to dense sand, overlying mica schist bedrock. A generalized subsurface profile is shown in Fig. 1. The historic fill stratum is about 10 to 45 feet thick, and generally consists of loose to medium dense sandy soils with varying proportions of silt, gravel, and miscellaneous debris such as brick, concrete, and glass fragments. The underlying former river bottom deposit stratum is up to about 15 to 20 feet thick, and generally consists of very soft to very stiff clay and lenses of very loose to loose sand. Medium dense to dense sand was generally observed below the historic fill and former river bottom deposit strata and overlying bedrock. Top of bedrock was generally observed at about 80 to 105 feet (i.e. at about el -75 to el -100), except in the southeastern portion of the site where the top of rock was observed as deep as about 140 feet (i.e., at about el -135). Groundwater levels typically ranged between about el 1.5 and el -0.5."

Jan 1, 2016

By Clayton A. Signor

Abstract: Expansive soils cause more damage to structures annually than a combination of other major natural disasters. Because of the cost to our society, all means and methods need to be fully explored to mitigate the problems associated with expansive soils. This study will present a foundation design approach that is underutilized in this application, driven piles. The main objective of the study is to present pile test results and analysis from four driven pile project sites in three types of expansive soils found in central Texas: Del Rio formation, Taylor/Navarro formation, and expansive alluvium. High strain dynamic pile tests were conducted on each of the four studies with rigorous signal matching analysis from the CAse Pile Wave Analysis Program (CAPWAP). Ultimate pile capacities ranged from 73 to 311 kips with an average of 61% of the total capacity coming from the pile shaft and were two to six times the structural capacity needed. Allowable loads calculated from Modified Gates dynamic formula best modeled allowable test results. Average unit skin frictions ranged from 0.50 to 4.71 ksf. Restrike pile tests of 1 to 17 days after initial driving reported 30 to 100% shaft capacity gain. All open-ended pipe piles driven produced soil plugs ranging from 4 to 14 feet thick. Small diameter, thick-walled, open-ended pipe piles reached penetration of twice the depth of designated zone of seasonal moisture change without problem. The observed production rate of the driven piles was on average 8 minutes, which implied daily production of 15 to 40 piles. Predrills or augered holes should be specified for underground obstructions found in soil investigation.

By N. Pajunen

The basic objectives of current EU waste policy are to prevent waste and promote re-use, recycling and recovery to reduce negative environmental impact (2008/98/EC). In this paper, we focus on drivers and barriers for sustainable development by decreasing amount of waste and increasing material efficiency. Main target is to understand what are the most efficient drivers for environmental friendly decision making for reasonable consumption and use of raw materials. Environmental control instruments usually mean those actions the regulatory authority uses to control and limit environmentally harmful behavior of companies. A major change in the environmental control system took place in the 1980s with the focus moving from specific environmental issues to the environment as a whole. The environmental control system i.e. the legal (administrative), economic and informative instruments focuses on prevention. Before and still, the legislation is one of the main drivers in improving material efficiency. In this paper, we focus on drivers and barriers for effective industrial material use, and mainly on drivers. The objective of this study is to analyze how the drivers are working and are there any possibilities to influence on those. Our aim is also to introduce few examples of the existing supply chains and the drivers for better environmental performance and material efficiency. These examples are also compared with ideal reference scenarios. Our main research question in this article is: ?Are the financial issues the most important driver for environmental friendly strategic decisions?? In addition, retell the story from another perspective: ?The most important barrier for environmental friendly innovations seem to be the investment cost, the high risk involved in committing capital to unproven technology.? Other drivers, like the corporate social responsibility, stakeholder pressure, and general public pressure, will also affect the final decision. This article is based on research projects and literature. Keywords: drivers, decision-making, environmental management, saving primary raw material, material efficiency, sustainable production, critical raw materials

Sep 1, 2012

By Gary MacDonald

What is the primary function of an impact assessment? Many people at the International Association of Impact Assessment?s (IAIA) annual conference said that it is time to return to the fundamentals and consider the underlying drivers of impact assessments ? human health, safety and security. This fall, managers struggling with those fundamentals will receive extra support when a new course focusing on health and socially responsible security is launched online and in British Columbia, Canada, home to many of the world?s junior miners. Now in its 33rd year, the IAIA conference recently held in Calgary, Canada, typically brings together a range of professionals who work in the impact assessment field, including academics, as well as people conducting applied disciplines, such as social and environmental performance management. It is a chance for people grappling with how to assess impacts from projects (for example, dams, mining and other extractive projects), to compare notes and to talk about developments in how to measure, track and report on them. The comments about returning to fundamentals rose as participants talked about the ongoing and increasingly recognized divergence between three main impact assessment streams: environmental, social and health (EIA, SIA and HIA, respectively). Discussions in sessions and in the corridors included calls for streamlining, for integration, for improvement and sharing of practice ? particularly in the HIA stream, where those deeply engaged in the health discipline questioned how HIAs and their intended outcome of protecting human health can be better integrated into the EIAs or SIAs that dominate the impact assessment realm. EIAs and SIAs have become the main tool, particularly from a permitting perspective for large-scale mines, but seem to leave projects with little real information about what they need to do. Human health is not the only concern re-emerging. Although not reflected at the conference, there appears to be an emerging understanding of the need to link the determinants of health with socially responsible security practices. Companies conducting independent social performance assessments for international financial institutions based on the International Finance Corporation?s Environmental and Social Performance Standards increasingly wrestle with both community health and security issues as extractive companies encounter challenging social environments around the world. Once again, the intended outcome is to better protect human health, including avoiding health impacts from conflict, abuses and violence.

Aug 1, 2013

By R. K. Matheson

THE Nivloc mine is 9 miles west of Silver Peak, Esmeralda County, Nevada. It has been operated by Desert Silver, Inc., since the summer of 1937. The cyanide mill treats 19o tons of silver-gold ore per day. In March of this year the main operations were about 2000 ft. west of the main shaft, which served as the downcast air passage for the mine. The mechanical blowers in use were sufficient to ventilate the west end at that time, but it was foreseen that as the mining area was extended ventilation would be an increasingly difficult problem, especially during the summer months. It was decided, therefore, to continue a raise from a point 100 ft. above the highest mining level (440-ft. level) to the surface; a distance of 443 ft. at approximately 65° From this point 40 ft. of drifting would be necessary to connect with a shallow shaft on the surface. (Fig. I.) All the raise was serviced from the 440-ft. level; costs and progress obtained in the initial 100 ft. are included in the following pages. CHOICE OF RAISE A raise in this locality would have four objects: (I) to provide an ample supply of fresh air to the working places; (2) to explore the vein from the highest mining level to the surface; (3) to provide waste fill for stopes in the area, and possibly provide a transfer for waste from the surface; (4) to provide an emergency exit in the west end of the mine. Before the mining of an ore shoot in the eastern part of the mine, a similar raise had been driven for purposes of ventilation and exploration. This raise and subsequent mining showed the vein to be noncommercial for a distance of about 250 ft. below the surface. However, in the area under operation, old surface workings showed occasional values. Thus from a development standpoint the raise was an excellent prospect. The raise chosen was a three-compartment, stulled raise having two chutes and a manway. The manway inside timber measured 4 ft. 8 in. by 4 ft. 6 in.; it carried air and water pipes, a ladderway and a slide for a timber skip. The two chutes would be used for drawing off the muck and the cleaning of the bulkhead, as well as for ore and waste passes, which would be especially useful for lateral exploration from the raise. The fairly large cross section of the raise (6 by 15 ft.) would provide a large quantity of waste for backfilling, and more could be obtained from a glory hole on the surface. TIME SCHEDULE As speed in completing the raise was the main requisite, three shifts were considered, but two shifts were decided upon when it was found that three would necessitate considerably larger fans than those available for clearing the raise. The main diffi-

Jan 1, 1942

By P. S. Miller, S. H. Ash

EXTENSIVE and diversified resources justify large populations and great industries. To carry on the business of commerce and meet the demands of large populations, the utilization of tunnels in some form for transportation purposes constitutes an important link in modern civilization. The driving of tunnels has been appropriated by the tunneling branch of the heavy-construction industry, and the progressive steps taken by modern tunnel builders were not even dreamed of 50 years ago. Great strides have been made toward more rapid progress in tunneling in the United States during the past 10 years. Tunneling consists of a definite cycle of operations developed from ideas that are crystallized and translated into action programs through various engineering phases that begin with the first preliminary survey and do not end until the job is completed. Once the line of the bore is established and a time set for the completion of the work, the face must advance according to estimates prepared before the work commences. This schedule must be followed in regular sequence from the moment the drills start against a new face of rock until they are ready again to drill the succeeding face, constituting a round.1 Mining is largely tunneling carried on under conditions often more inherently hazardous than actual tunnel construction, but for various reasons1 tunneling is more hazardous than mining in any branch of the mineral industry, On the other hand, obstacles are sometimes encountered in heavy-construction tunneling projects that when met in mining enterprises do not offer comparable tasks to avoid or overcome them. One of these is the existence of water under high pressures. In mining enterprises, various alternatives offer a solution in driving a tunnel, even to the extent of its discontinuance or the abandonment of the mine, but a "construction" tunnel usually must go forward because some important project depends largely if not entirely upon it. This paper describes an unusual method of driving a water-supply tunnel through rock carrying water under pressures and conditions that did not permit the use of ordinary tunneling methods. THE DELAWARE AQUEDUCT The new Delaware aqueduct is a Manhattan project of some magnitude; when completed, it will contain what probably will be, for some time to come, the longest tunnel in the world. Various features in its construction are currently described in the trade journals of the construction industry, and informative engineering details are given in the Delaware Water Supply News, published twice a month by the Board of Water Supply of the City of New York. Work was begun on this project on March 24, 1937. The tunnel will convey water from reservoirs at the headwaters of the Delaware River to the City of New York.

Jan 1, 1942

By Jim Rix, Ken Been, Nihal Bohra, Anthony Rice, Juan Lopez

"A temporary bridge, supported on steel pipe piles, was built to expedite the construction of a breakwater structure off the western coast of Peru. The bridge provided access for dump trucks to the breakwater across a 342 m (1122 ft.) wide navigation channel from a liquefied natural gas (LNG) loading facility, at the end of a 1.3 km (0.82 miles) long permanent trestle, in 15 m (50 ft.) water depth. After the completion of the breakwater, the temporary bridge was removed, and the piles were extracted approximately one year after the initial driving. The bridge deck was typically supported on pairs of 914.4 mm (3 ft.) diameter, 18 mm (0.708 inch) wall steel pipe piles spaced at 7.5 m (24.6 ft.) across the bridge width and 18 m (60 ft.) along the bridge length. In an attempt to reduce the driven pile embedment, an inner closure plate was installed at 2.7 to 7 m (9 to 23 ft.) from the pile toe to force closed-end behavior. The piles were designed to carry 3400 kN (383 tons) axial compression load, and a minimum of 8 m (26 ft.) embedment was specified to provide sufficient resistance to the lateral loads.The subsurface conditions consisted of cemented conglomerate of sand, gravel, pebbles and some boulders, locally known as the Cañete Formation. The driven pile embedment varied widely, between 8 to 24 m (26 to 79 ft.). A significant portion of each pile was above the seabed, passing through seawater and up to the bridge deck, and was therefore unsupported. The extraction of the piles was challenging due to the subsurface conditions, presence of significant water column, pile weight, and the inner closure plate. Several different approaches were attempted before the piles could be successfully extracted. This paper summarizes the difficulties encountered and observations made during the driving and extraction of these piles."

Jan 1, 2017

By Nihal Bohra

A temporary bridge, supported on steel pipe piles, was built to expedite the construction of a breakwater structure off the western coast of Peru. The bridge provided access for dump trucks to the breakwater across a 342 m (1122 ft.) wide navigation channel from a liquefied natural gas (LNG) loading facility, at the end of a 1.3 km (0.82 miles) long permanent trestle, in 15 m (50 ft.) water depth. After the completion of the breakwater, the temporary bridge was removed, and the piles were extracted approximately one year after the initial driving. The bridge deck was typically supported on pairs of 914.4 mm (3 ft.) diameter, 18 mm (0.708 inch) wall steel pipe piles spaced at 7.5 m (24.6 ft.) across the bridge width and 18 m (60 ft.) along the bridge length. In an attempt to reduce the driven pile embedment, an inner closure plate was installed at 2.7 to 7 m (9 to 23 ft.) from the pile toe to force closed-end behavior. The piles were designed to carry 3400 kN (383 tons) axial compression load, and a minimum of 8 m (26 ft.) embedment was specified to provide sufficient resistance to the lateral loads. The subsurface conditions consisted of cemented conglomerate of sand, gravel, pebbles and some boulders, locally known as the Cañete Formation. The driven pile embedment varied widely, between 8 to 24 m (26 to 79 ft.). A significant portion of each pile was above the seabed, passing through seawater and up to the bridge deck, and was therefore unsupported. The extraction of the piles was challenging due to the subsurface conditions, presence of significant water column, pile weight, and the inner closure plate. Several different approaches were attempted before the piles could be successfully extracted. This paper summarizes the difficulties encountered and observations made during the driving and extraction of these piles.

By Toby Forney, Joshua Schoonover

In typical surface quarry operations, productivity and efficiency related to pit development begin with drilling and blasting efforts. By embedding technology within drilling and blasting operations, blast results can be tailored to benefit the quarry by driving continuous improvement of production. This technical paper will focus on the continuous improvement efforts at a cement limestone quarry in Maryland and how those efforts have impacted mining production, safety, and efficiency with the application of specific blasting technologies.

Feb 6, 2023

By P. Holman

I would like to start this paper by looking back about twenty years to see where we have been in the mining industry. We will also look forward a bit and talk about what lies ahead. Here is what has happened to the world economy since the 1970s. Economic growth was strong in the early 70s, but slipped into a recession in the middle of the decade. Then, after a fairly decent recovery recession struck again in the early 80s and since then growth has been rather sporadic. All in all, it has been a real roller coaster ride. There will continue to be plenty of ups and downs in the world economy in the future.

Jan 1, 1993

The current drill-and-blast method of tunnelling is cyclic and, for this reason above all others, has a future application potential which is lower than that of continuous methods. There is scope for progress in several facets of today's drill-and-blast tunnelling. But even if each of its unit operations and the synthesis of these were to be optimised, this conventional method will, in the long term, fail to be a serious competitor for tunnelboring machines (TBMs), roadheaders and the like. If its role in tunnelling is not to decline at an increasing rate, drill-and-blast will need to be transformed into a continuous system. Boring and cutting machines consume considerable energy (and expenditure) in creating rock fragments which are smaller than those required by muck-handling equipment. In this respect, blasting is more efficient. Mechanical methods are also less versatile and flexible and, when planning proceeds on a basis of meagre or inadequate geological data, cannot be costed as accurately. Currently, research gains for TBMs and roadheaders are greater than those for conventional tunnelling. If (as is likely) the disadvantages of mechanical methods continue to be reduced at a greater rate, the swing away from drilling and blasting will gain momentum.

Jan 1, 1987

By W. L. Saunders

(New Haven Meeting, February, 1909.) This paper deals specifically with heading-driving as distinguished from the broader term tunnel-driving. A heading is a pilot or path-finder for the main tunnel. Some headings are complete tunnels in themselves; that is, conditions at times warrant driving a heading the full diameter of the proposed tunnel. A tunnel 10 ft. in diameter might be driven to advantage through a single heading, provided the nature of the material admits, but it usually pays to drive rock tunnels of large diameter through the heading-and-bench system. Much de-pends upon the material, as in soft ground tunnels of much larger diameter are driven in a single heading. In mines, the tunnels, drifts, cross-cuts, adits, etc., are usually of small diameter, hence the driving of headings applies to completed tunnels in minim-work, except, of course, in cases like drainage-tunnels and main entries leading into coal-mines, where conditions call for tunnels of large diameter, approximating those driven for railway-service. In building aqueducts the tunnels are driven from 6 to 8 ft. in diameter up to 15 or 20 ft., while in railway-service the dimensions vary from 18 to 30 ft. in diameter. There is no department of rock-excavation so difficult as that of heading-driving. This work. also belongs to the most expensive class in rock-excavation. A heading is driven .directly in the solid. There are no lines of lesser resistance towards which to direct the energy of the blast, but. the material must be blown out by main force. The completion of the heading simplifies all the rest of the work of excavation. It is easy, for instance, to enlarge a heading either from above, below or oil the sides, by breaking towards the open face through holes approximately at right angles to the axis of the heading; or the enlargement sometimes takes place by holes driven outside

Apr 1, 1909

By J Taylor, M Smith, A Tunnadine, D Nikolakopoulos

As Olympic Dam rapidly expands into the Southern Mine Area (SMA) the Mine Geology team has concurrently ramped up underground diamond drilling to sustain rates of above 175 km/a. With >10 underground rigs double-shifting, traditional paper sections used for the management of drill programs were no longer optimal due to scale of operations. An opportunity was identified to modernise monitoring of all underground diamond drill programs, through the integration of logged copper sulfide estimates with Olympic Dam’s first-fully integrated deposit-scale geological model in Leapfrog Geo. This paper describes the transition within the Mine Geology team from reliance on 2D paper sections, towards near-real time 3D geological modelling for optimising end-of-hole decisions in the field. This transition was enabled by innovative database solutions informing locally constrained implicit models, limited by a distance buffer around active underground fan drilling. Due to the high volume of historic drilling, there were significant computational challenges with the implementation of daily production style implicit models at Olympic Dam and initial testing of regular updates to implicit gradeshells and sulfide domains required in excess of 12 hrs to run. The enabling solution was to optimise the interfaces between the AcQuire database, Deswik MDM and Leapfrog Geo to create a dynamic, streamlined workflow that was easily completed by Mine Geologists in accordance with daily production duties. Geologists are now building rapid implicit models for a range of variables from an integrated data set of logged sulfide estimates and existing assays, spatially constrained by 150 m buffers around active drilling using a unique drill fan identifier flagged during the planning phase. Once the live-implicit models are updated, they are exported for visualisation on field tablets to be used during logging and core checks at the start and end of every shift. To manage the risk of ‘going digital’ interpretation remains at the forefront of the drill section close-out process, with Mine Geologists critically reviewing the finished sections on a standardised template with new learnings wireframed and communicated to stakeholders. The Live Field Model has enabled a step-change in the geological effectiveness of diamond drilling, reducing over – and under-drilling ore-waste at Olympic Dam continuing to push drilling effectiveness towards 20 per cent of intercepts >2 per cent Cu. In addition, upside or risk identified during the proactive management of drilling execution can be rapidly capitalised or mitigated.

Mar 22, 2022

By E. E. Mason

THE Myrtle group of mining claims is situated on Barkerville mountain in the Cariboo mining district of British Columbia, west of the old mining town of Barkerville. An 1,800-foot adit, known as the Shamrock tunnel, was driven in 1935-36 from the Barkerville road and in the general direction of the Myrtle group. It was proposed to enlarge this adit to more convenient section, extend it 2,500 feet int0 Myrtle ground, and from there drive a main entry 3,000 feet along the length of the group. Several laterals were also to be driven off this main entry as part of the tunnel schedule. It was thus originally proposed to drive 5,500 feet of new adit and 1,800 feet of laterals, a total of 7,300 feet of new work. Work was commenced with a bulldozer on April 21st, 1941, cutting a bench on the hillside for a plant site. The power plant was ready for operation on August 8th. Slashing and re-timbering of the old adit rook longer than was expected. It was found that 57 per cent of the length required timbering, chiefly by fore-poling, and there was also trouble in several sections with swelling ground. First round in the new face was taken on September 17th, when a 2-shift daily schedule was commenced. Due to delays in delivery of electrical equipment, it was not possible to add the third shift until November 14th. From then on, a 3-shift daily schedule was maintained with the exception of holidays and fortnightly change Sundays until August 1st, 1942, when shortage of labour caused the dropping of a shift. All work was suspended on August 14th. The ground through which the tunnel passed was such that the driving was often interrupted by the need of protective timber at the face. Further, crews were continuously employed timbering behind the face, and in maintenance of timbered sections in swelling ground. Roughly 980 feet of the new workings are now timbered, about 21 per cent of the total.

Jan 1, 1942