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By P. Momni, D. Ersenkal

Equator Principles (EPs) are a set of guidelines developed and adopted by a series of financial institutions for assessing and managing social and environmental issues in project financing. Established in 2003, EPs are now adopted by some 68 financial institutions from 27 countries. As more and more financial institutions join this global initiative, it is important for project owners to have a logical framework embedded into the project lifecycle to reduce the risk of non-compliance which could result in costly delays. This paper outlines a proactive approach for project developers in order to integrate environmental and social aspects into entire project lifecycle.

Jan 1, 2010

By Ellsworth R. Spencer

An assessment of U.S. western hardrock miners? noise exposures was conducted as part of a multi-year National Institute for Occupational Safety and Health (NIOSH) survey of noise exposures in each sector of the mining industry. Noise from selected mining equipment and operator noise exposures were measured, analyzed and tabulated for dissemination to the participating sites and are being used to direct NIOSH research and interventions to address the greatest noise hazards. Eighty-two noise dosimeter measurements were obtained, along with time-motion studies as the miners operated hardrock mining machines. Of the operators, 96% had daily noise doses that exceeded the U.S. Mine Safety and Health Administration?s (MSHA) permissible exposure level. The average gold miner dosages while operating the following equipment were: haul trucks - 261%, load-haul-dumps (LHDs) - 235%, single boom drills - 221%, bolters - 214% and dual boom drills - 163%. The worst exposure level was a silver miner with a daily dose of 873%. Time-motion data showed that this miner?s exposure accumulated most rapidly while operating a jackleg drill. These results will be used to help prioritize noise control development by NIOSH and other partners.

Jan 3, 2010

By E. R. Spencer

An assessment of U.S. western hard-rock miners? noise exposures was conducted as part of a multi-year National Institute for Occupational Safety and Health (NIOSH) survey of noise exposures in each sector of the mining industry. Noise from selected mining equipment and operator noise exposures were measured, analyzed, and tabulated for dissemination to the participating sites and are being used to direct NIOSH research and interventions to address the greatest noise hazards. Eighty-two noise dosimeter measurements were obtained, along with time-motion studies as the miners operated hard-rock mining machines. Ninety-six percent of the operators had daily noise doses that exceeded the Mine Safety and Health Administration?s permissible exposure level. The average gold miner dosages while operating the following equipment were: haul trucks - 261%, load-haul-dumps (LHDs) - 235%, single boom drills - 221%, bolters - 214%, and dual boom drills - 163%. The worst exposure level was a silver miner with a daily dose of 873%. Time-motion data showed that this miner?s exposure accumulated most rapidly while operating a jack-leg drill. These results will be used to help prioritize noise control development by NIOSH and other partners. Disclaimer: The findings and conclusions in this report have not been formally disseminated by the National Institute for Occupational Safety and Health and should not be construed to represent any agency determination or policy.

Jan 1, 2009

By Rakam Lama Tamang, Michael J. Byle, Stephen Ernst

"For various reasons, dredging may become necessary in front of existing bulkhead walls, either for channel deepening or for environmental remediation of contaminated sediments. The removal of sediments at the base of bulkhead walls removes support for the toe of the wall that must be assessed. Evaluation of this impact can be problematic for aging bulkheads for which no design or construction records exist. This paper will address the steps that should be taken in investigation and analysis to assure proper assessment and means to address uncertainties and gaps in information. The steps include pre-investigation data review, field inspection, geotechnical and geophysical investigation tools, parametric analysis and design tools. Examples from several bulkhead assessment projects will be provided that include a variety of conditions and tools for application. The focus of the paper will be on the integration of technologies to assess bulkhead geometry, geotechnical properties and stability, structural safety and constructability issues with removal of support, and means of temporary and permanent stabilization for environmental applications.IntroductionBulkheads and quays have existed as long as there have been waterfront activities. Some of the earliest date back to 1200 B.C.E.(Raban, 1987), however in the United States few predate the eighteenth century. Most extant bulkhead structures, and all steel sheet pile bulkhead walls date from the early 20th century or later. These structures function to protect the shore from erosion, support landside activities, and serve as place to moor and offload vessels. Regardless of the age or usage of existing bulkheads, it is essential to assess and protect them if needed where removal of soils on the water side of the bulkheads is planned to dredging.Waterfront BulkheadsExisting bulkhead structures can be classified into two types: Cantilevered, and anchored. Cantilevered walls are completely supported by the soil on the water side, while anchored bulkheads are supported both by the soil on the water side and anchorage on the land side (Figure 1). Walls may be constructed of timber, steel, or concrete. Timber walls may be lagging with soldier piles, cribbing with soldier piles, or timber sheeted such as Wakefield walls (Figure 2). Steel bulkheads are most commonly constructed using sheet piling comprised of interlocking A or Z shapes, though some historic walls were constructed with flat sheets. Precast concrete sheet piling has also been used in construction of bulkhead walls. Anchorage may be provided by steel bars or tendons attached to deadmen, sheet piling, driven piles, or earth anchors."

Jan 1, 2017

By Sandeep Kumar Jeripotula, Govinda Raj Mandela, Aruna Manglapady

The main aim of this work is to evaluate whole-body vibration (WBV) of dozer operators based on three sitting postures (i.e., with 15° lean forward inclination posture, vertically erect posture with no inclination, and with 15° lean backward inclination posture) in Indian surface coal mines. A seat pad tri-axial accelerometer was used to collect WBV data from six dozer operators for three different sitting postures. Results showed that except for Dozer-1, 2, 4, and 5 operators during lean forward sitting posture and Dozer-4 operator during vertical erected posture, no other dozer operators have exceeded an exposure limit value (ELV) of 1.15 m/s2 in any of the considered sitting postures. Similarly, the vibration dose value (VDV) based on exposure action value (EAV) of 9.1 m/s1.75 has surpassed for all the dozers. But no dozer operator has exceeded an exposure limit value of 21 m/s1.75. The outcome of the study infers that based on “above health guidance caution zone (HGCZ)” for daily vibration exposure, i.e., A(8) measurements, for the operator sitting in lean backward postures the vibration amplification was reduced by 32.89% less compared with lean forward posture and 16.23% less when compared with vertically erected posture. Similarly, based on VDV(8), the exposure to vibration for the lean backward posture was reduced by 33.34% when compared with lean forward posture and 17.11% less when compared with vertically erected posture. Based on the above observation, it is concluded that lean back inclination with a trunk flexion of 15° is a favorable sitting posture, as it exposes the dozer operators to minimum vibration.

By H. Fujihara, K. Uesugi, H. Toda, A. Takeuchi, K. Shimizu

"Hydrogen is trapped at a variety of microstructures, for example grain boundaries, dislocations and particles. It is thought that hydrogen trapped at trapping sites is redistributed to the other sites under loading and then brittle fracture occurs with hydrogen accumulation. In order to understand hydrogen embrittlement behavior, it is necessary to investigate the time evolution behavior of hydrogen accumulation at each trap site. In the present study, changes in hydrogen distribution are observed under stress using Kelvin force microscopy (KFM) that can visualize hydrogen concentration distribution on material surface at high resolution. Spot-like hydrogen enriched regions are observed on the surface of a material. In addition, hydrogen depleted regions are observed around those enriched regions, and the appearance of hydrogen trap due to particles existing near the material surface is revealed. On the other hand, hydrogen trapped at grain boundary can be visualized. From in this result, it was suggested that crystallographic factors influence hydrogen accumulation. The relationship between initiation and propagation of intergranular crack and hydrogen accumulation under stress will be discussed.INTRODUCTIONHydrogen present in a metal sometimes has significant effects on various properties. Hydrogen in a metal is trapped at a variety of microstructure, for example dislocations and grain boundaries. Grain boundaries, dislocations and micro pores are the major trap sites in aluminum alloys. Some researchers considered that hydrogen redistribution and accumulation between these trap sites in a material with loading plays an important role in the brittle fracture behavior. In general, in intergranular fracture and quasi-cleavage fracture, the hydrogen trapped at grain boundaries and dislocations contributes to fracture behavior, respectively. Recently some researchers have shown that the ductile fracture in aluminum alloys is resulted from growth and coalescence of hydrogen micro pores. Analysis using first principles calculation indicates that intergranular fracture occurs when hydrogen concentration reaches 20 atom H/nm2ongrain boundary. From this report, it is considered that hydrogen redistributed during deformation accumulates locally in order to cause hydrogen brittle fracture. In order to understand hydrogen embrittlement, it is necessary to investigate the time evolution behavior of hydrogen accumulation at each trap site. In the present study, we evaluate the relationship between hydrogen accumulation behavior and fracture behavior in Al-Zn-Mg based alloys. In-situ observation was made by combining the tensile test with Kelvin force microscope (KFM) that can visualize the hydrogen concentration distribution on the material surface with high resolution. We also investigate the relationship between hydrogen distribution behavior and crystal orientation."

Jan 1, 2018

By Danielle Nhanqulumanga, Pranith Bhatt, Snehal Patel, Khadeeja Priyan

The Bi-Directional Static Load Test (BDSLT) is a test that determines the capacity of piles when loaded under bi-axial static compression. In recent years the BDSLT has seen an increase in demand due to its safety, speed, and affordability. This innovative foundation testing method has been universally used over the last 50 years, however respective codes and standards have only been published within the recent years. Detailed test procedures and methodology are expatiated in the ASTM D8169 M-18 [1], and the IRC 78 2014 Clause 709.2.5. [2] These standards provide the minimum requirements for the execution of the BDSLT. In this paper we did a comparative study of both standards envisaging to bring attention to the similarities and discrepancies found therein, with an aim to highlight the impacts and challenges that differing provisions of each standard could pose on the conduct of the BDSLT. Discrepancies found have been explained on the basis of geotechnical engineering theories and relevant field occurrences observed by superior engineers. Additionally, we emphasize on the relevance of experienced engineer’s judgement when utilizing the standards.

Sep 1, 2022

By Richard Simon

This paper presents an ongoing study on the use of borehole breakouts to estimate in situ stresses at depth in a Canadian underground mine. Breakouts were identified using an acoustic televiewer (ATV) probe. Rock samples were tested in a laboratory to determine their failure curve. Breakout analyses were performed using a 2D failure criterion and a multiaxial failure criterion. Analyses were carried out using both short-term (peak) and long-term strengths (the latter considered here as being represented by the damage initiation threshold DIT). The analyses have shown that the use of the longterm strength and a multiaxial failure criterion leads to results that are more consistent with stress measurements performed in the field, in the vicinity of the mine.

Jun 1, 2012

By D. W. McGlashan

[Comideha;tion o 4 chyakd- chem and aLtuctund phopetttiu o auRdide nm&, The in~o/uncction gained h ;to be uned ;to iM;tmph& ( I! dnukey bho hen mind-aundacu , ( 2 ) modidicakio~n 06 ;the minmd n~tdacu, and (3) eac;tiom at ;the mind adac fnom ;thu e baic din oipfina, concep;tc, wLth hegattd ;to .the changen kha;t awtgacu undehgu, heac;tiom kha;t might take place, ,the geom&y 04 ;the inkmduce, ;the nkde 04 diddmenk &om and iom in ;the intmdace, and okhm phyaicd and chemicd pttopemXu od an intmdace mun;t be developed, weighed and appfied. The au/tho~ ded wah thue concep;tud connidmatiom @om which hypokhuu me n& ko denchibe khe envhomenkd-ivttadaciae hela;tiomhipa doh nevmd nddide minettah, The ch&enge and moltivation in khe hu eattch h in a henhe a deattch doh baic dad and helcctiomkipa needed doh accompfi he&.] INTRODUCTION Qualitative and quantitative explanation of particulate solid separations are unknown entities because of the lack of adequate models and mathematical relationships to explain the activity occur- ring between the solid and liquid phases. It is a transitional region in which it is difficult to ascertain the mechanisms of adsorption of ions, molecules, etc. on mineral surfaces, as well as other secondary reactions which occur in interfacial regions. Thus, in this paper the authors deal with conceptual considerations from which hypotheses are set forth to describe the environmental- interfacial relationships for sulfide minerals.

Jan 1, 1968

By M Ridd

The Pasminco Century Mine (PCML) is located 250 kilometres north-north-west of Mt Isa in Queensland. As one of the worldÆs largest zinc mines, PCML comprises mining and milling operations at Lawn Hill, concentrate filtering and shipping facilities at Karumba in the Gulf of Carpentaria, and a 304 km slurry pipeline connecting the two operations.Mineralisation at Century occurs in the upper part of the Lawn Hill formation and is comprised of siltstones, shale and sandstone. Pyrite occurs immediately above the mineralised sequence, and throughout the footwall carbonaceous shale forming the lower proportion of the deposit. Zinc predominantly occurs as sphalerite (ZnS) and lead as galena (PbS). These sulfides are very fine-grained and may oxidise rapidly upon exposure. The pyrite, sphalerite and galena are the main potential sources of acid rock drainage (ARD) or heavy metal leachate at the mine site.To minimise the generation of ARD in the waste rock dumps, they are constructed in a specific manner and waste rock is classified into the following three classes based on competence and acid forming/consuming capabilities:Class 1: Competent rock, non-acid forming or acid-consuming material. Class 2: Non-competent, non-acid forming or acid-consuming material. Class 3: Acid-forming material. The generalised Waste Rock Dump Design for current operations comprises an outer zone of Class 1 material and inner zone with Class 2 and 3 material. Limestone is the Class 1 material used for both its structural support and acid neutralising capacity. Reserves of limestone at the mine site are limited. Net acid generation (NAG) tests confirm that a mix of limestone and shales can be net acid consuming.Field based and laboratory based trials have been established at PCML to quantify blending levels of limestone and shale that will produce leachates both neutral in pH and low in metal/salt concentrations. This paper will discuss the first six months results (of a two-year sampling program) from the trials.

Jan 1, 2004

By Joseph Peterson, Alexander May

The Bureau of Mines used geochemical modelling computer programs to characterize a site containing lead slag generated by a lead processing facility. Tests for toxic elements by the U. S. Environmental Protection Agency (EPA) extraction procedure showed that all elements except lead were in compliance. Concentrations for lead ranged from 28 to 30 ppm. However, analysis of water samples from monitoring wells resulted in no lead concentrations that exceeded the National Drinking Water Standard. A discussion of a computational program to calculate concentrations of lead species and several other ions is presented.

Jan 1, 1991

By Daniel de la Rosa, Juan Manuel Mayoral, Damián Vital

"This paper presents a numerical study regarding the loads, and the corresponding damage, taken by the primary and secondary lining of a tunnel built in cemented fine-grained stiff soils. This study aims at establishing more rational design criteria that take into account explicity the lining performance. A 3.5 km long tunnel to be built in a densely populated northwest area of Mexico City, was considered as case study. Series of three-dimensional finite difference models, developed with FLAC3D, were used to simulate the tunnel construction, and to compute the ground settlements, internal forces, bending moments, and displacements acting both on the primary and secondary tunnel linings. Interaction diagrams were used to study the lining performance. Several advancement lengths, and tunnel covers were considered to establish their impact on the loads transferred to the tunnel lining. A practice-oriented damage criterion for tunnels was proposed based on the interaction diagram analysis. INTRODUCTION Lining performance during conventional tunnelling, CT, as defined by the International Tunnel Association, ITA (ITA 2009) is strongly affected by the construction procedure. Special attention must be taken in cemented fine-grained materials, such as those found in the northeast portion of Mexico City, due to the potential of fragile failure (i.e. the soil fails suddenly without important deformation) that these soils may exhibit. During CT, it is assumed that the ground strength contributes to the stability of the excavation, as long as the lining is built correctly. It is common practice to consider two structures, which together form the tunnel support: 1) A primary lining, which is a flexible support, which allows excavation walls to deform to mobilize part of its shear strength, and thus contributes to the tunnel self-stability, and 2) A secondary lining. Commonly, the primary lining consists of several layers of shotcrete. In this case the installation method guarantees perfect contact between the lining and the excavation perimeter. The secondary lining, if required, is used to withstand the load conditions in the long term and also has an esthetic function. This paper presents a numerical study aimed at establishing a performance damage criterion for the primary and secondary lining design in cemented fine-grained stiff soils. Due to the lack of data, the strength and deformation parameters were established through empirically-derived relationships. Three-dimensional finite difference models were developed to simulate the tunnel construction, and compute ground settlements, internal forces, bending moments and displacements acting both on the primary and secondary tunnel linings. Interaction diagrams, along with a damage criterion were used to study the lining performance. From the results gathered insight was gained regarding tunnel lining performance during CT."

Jan 1, 2016

By G. Mark Aylmore

Various processes have been developed using a combination of elevated temperature and chemical treatment processing to recover Li from silicate minerals. To facilitate further process development, a comprehensive understanding of the deportment of Li and associated minerals in ore bodies is essential to allow the industry to predict the response of ore reserves to metallurgical treatment options. This paper describes results from the integrated use of the John de Laeter Centre’s state of the art analytical and mass spectrometry techniques to characterise a selection of Li bearing ore bodies and determine their amenability to potential processing options for the extraction of Li. The mineralogy, mineral associations, and liberation characteristics of ore-bearing and gangue minerals were characterised using a combination of the TIMA and XRPD studies. The Li content and distribution within minerals were defined using LA-ICPMS and field emission scanning electron microscopy techniques (EBSD, ToF-SIMS) and atomic probe microscopy.

By F. Segobia, H. Lozano, M. Portal, F. Ysla, L. Goicochea

This case study evaluates the long- term physical stability of various historical mining structures remediated by the Center for Mining Environmental Research and Studies (CIEMAN) in Hualgayoc, Cajamarca, Peru. The region has a long history of mining activity, with remnants dating back to pre-Inca times. CIEMAN has assumed responsibility for remediating 286 environmental liabilities in the area, including adits, shafts, pits, tailings, and waste rock dumps. The study analyzes the methods employed to stabilize these structures, including geotechnical engineering techniques and revegetation. Long-term monitoring results are presented, assessing the effectiveness of remediation measures and predicting the future stability of the structures. This study highlights the importance of responsible remediation of mining environmental liabilities to ensure the safety and sustainability of communities and ecosystems affected by historical mining.

Feb 1, 2025

By Chris M. Haberfield, Neil D. Benson

The assessment of overall modulus (or stiffness) of a fractured weak to moderately strong rock mass is a key parameter in the design of civil engineering works in these materials. It also provides the highest level of uncertainty due to scale effects, anisotropy and the influence of joint frequency and joint stiffness. Using the example of the Melbourne Mudstone, this paper compares approaches using empirical rules based on intact rock strength, laboratory testing, in situ field testing, semi-quantitative assessment techniques based on rock mass classification and back analyses. L'évaluation du module (ou rigidité) global d’une masse rocheuse faible et fissurée a modérément forte est un paramètre principal dans la conception des travaux du génie civil dans ces types de matériaux. Elle fournit également le niveau le plus élevé d'incertitude due aux effets d’échelle, à l'anisotropie et à l'influence de la fréquence et de la rigidité des joints rocheux. En utilisant l'exemple du schiste de Melbourne, cet article compare des approches empiriques basées sur la force intacte de La roche, les essais expérimentaux au laboratoire, les essais sur site, les techniques semi-quantitatives d'évaluation basées sur la classification de la masse rocheuse et les analyses en retour. Die Schaetzung des allgemeinen Steifigkeit-Moduls des gebrochenen schwachen bis zu maessig starken Felsmassen ist eine Haupt- Annahme in dem Entwurf von Tiefbau-Projekten in diesen Materialien. Es verursacht den hoechsten Grad der Ungewissheit in Folge der Groessenordnung, Spaltorientierung und dem Einfluss der Haeufigkeit der Risse und Bruch-Steife. Unter Verwendung des Beispiels des Melbourner Tonsteine, vergleicht diese Darlegung die Anwendung der empirischen Regeln, die sich auf die Staerke des ungestoerten Fels Basieren mit Versuchen in der Material Pruefungsanstalt, Untersuchungen auf der Baustelle und halb-quantitative Schaetzungsverfahren, die sich auf die Felsmassen Klassifikation und fruehere Analysen stuetzen.

Jan 1, 2003

By Sibabrata Patnayak

A major problem during shovel excavation in oil sand mining is the variability of material diggability resulting in varying mechanical energy input, cycle time, energy consumption, wear, and stress loading of shovel dipper-andtooth assembly. This variability greatly influences the mining equipment performance. Different approaches such as empirical ground classification systems, analytical methods, and performance monitoring that are used to determine diggability of groundmass are reviewed. It is concluded that the existing empirical diggability classification systems are site specific and mostly based on rock and therefore, cannot be used for shovel excavation in oil sands. The O&K wedge test is a simple and useful index test for establishing correlations between cutting resistance and geotechnical properties of coal and other soft rock overburden material. But this test, when performed on small size unconfined oil sand samples, may not give reliable indication of diggability because of the boundary conditions on the specimens. Digging predictions made using analytical and laboratory digging models need to be verified with performance monitoring data to better understand the digging effort in oil sands.

Apr 1, 2005

By Hökmark. H., M. Lönnqvist

"The Swedish Nuclear Fuel and Waste Management Company are planning to construct a permanent storage facility for high-level nuclear waste at about 500 m depth in fractured crystalline rock. One potential concern for the long-term performance of the repository relates to large fracture shear displacements, since these may damage intersected waste containers. Although details in fracture surface geometries are known to influence slip magnitudes and distributions, fractures are commonly approximated as planar features with lab-scale properties due to lack of relevant field-scale data and to limitations in available modelling tools. The purpose of the work described in this paper is to explore the possibilities to use the distinct element code 3DEC to generate and analyze models with isolated, non-planar fractures and, based on the results of such models, get perspectives on the influence of basic disturbances such as ridges, steps and waves. Given the model set-up, fracture segments with orientations deviating from the critical one will contribute to stabilize the fracture. As a result, all analyzed non-planar fractures slip less than the critically oriented planar fracture. We demonstrate that the angle of deviation is the most influential parameter determining the slip magnitude for comparable surface geometries. Similarly inclined steps and ridges have almost equal slip reductions despite differences in surface area restricting the movement. Although it may be possible to translate the influence of such irregularities to an effective coefficient of friction that could be used as input to models with idealized planar fractures, additional analyses with randomly shaped and distributed asperities, different fracture sizes and with alternative stress loads, need to be carried out to devise a defensible strategy for this type of parameter variation. INTRODUCTIONThe Swedish Nuclear Fuel and Waste Management Company’s (SKB) concept for deep geological storage of high-level nuclear waste is the KBS-3 method according to which the waste will be encapsulated in copper canisters and deposited, surrounded by compacted bentonite clay, in vertical deposition holes at about 500 m depth in fractured crystalline rock (SKB 2011). A site has been selected in the Forsmark area, which is located some 120 km north of the Swedish capital Stockholm. One potential concern for the long-term performance of the repository that has been identified by SKB (SKB 2011) is related to large shear displacements along repository host rock fractures induced by a nearby earthquake, since these may cause mechanical damage to intersected waste containers. Due to lack of relevant data at the appropriate field scale and to limitations in available modelling tools, fractures are commonly approximated as planar features with lab-scale properties. The standard numerical tool, 3DEC (Itasca 2013), used in SKB’s rock mechanics analyses, for example, generates planar fractures by default. Results from dynamic 3DEC earthquake-models (Fälth et al. 2010) currently provide input to layout decisions, i.e., the diameter of the smallest planar fractures that must be avoided when deciding on waste container positions at different distances from potential earthquake faults. It is, however, well known that fracture surfaces are rough or undulating on a wide range of scales (e.g., Candela et al. 2012) and that such deviations from planarity influence the mechanical behaviour of the fractures (e.g., Dieterich and Smith 2009, Marshall and Morris 2012, Ritz and Pollard 2012). It will probably never be a realistic option to attempt to represent the geometrical complexity of a population of fractures of different size, shape and surface structure in any large-scale rock mechanical analysis relevant for the performance assessments of the nuclear waste repository. It may however be possible to find approximate ways to represent different styles and degrees of non-planarity by assigning mod"

Jan 1, 2015

By R. D. Begley, A. W. Khair

This paper presents an assessment of modeling techniques in predicting subsidence over longwall areas. Extensive instrumentation has been made, both at the surface and subsurface, at three longwall mines in northern West Virginia. Ground movements were monitored during a three- year period until subsidence ceased in these areas. A comparative analysis of empirical subsidence prediction techniques including graphical (NCB), profile function, influence functions (USBM, Bals', Knothe's, and zone area) will he presented. A brief geologic and topographic description of each site, along with the instrumentation and monitoring program, will also he presented.

Jan 1, 1990

By A. W. Khair

This paper presents an assessment of modeling techniques in predicting subsidence over longwall areas. Extensive instrumentation, both at the surface and subsurface of three longwall mines in northern West Virginia have been made. Ground movements were monitored during" a three year-period until subsidence ceased in these areas. A comparative analysis of empirical subsidence prediction techniques including, graphical {NCB}, profile function, influence functions (USBM, BAL'S, KNOTHE'S, and zone area) will be presented. A brief geologic and topographic description of each site along with the instrumentation and monitoring program will also be presented.

Jan 1, 1989

By R. J. Matetic

The Bureau of Mines, as part of a program to improve mine planning and development, is currently investigating the effects of pillar load transfer, which can impact mining operations within a multiple-seam configuration. A comparative study was performed at two separate mine sites to determine the effects of this load transfer mechanism. The Bureau installed and monitored instrumentation at both sites to gather pertinent data on rock mechanics. At mine site A overburden depth varied dramatically in the vicinity of the study area and reached a topographic high at the study site: inner burden thickness was less than a pillar width (40 to 45 ft) (12 to 14 m): floor heaving was experienced in both coalbeds where sandstone and/or shale floor units were observed: overlays of the mine layouts show pillars were not totally super-positioned: a maximum of 5 in (13 cm) of roof to floor convergence was measured and pressure readings indicated pillar core loading only and increased to a maximum of 7,000 psig (48,300 kPa) over instrument setting pressure.

Jan 1, 1989