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By Jean Habimana

The Detroit Upper Rouge Tunnel CSO Control Project will capture and store up to 201 MG of combined sewer overflow from 28 outfalls in Detroit, Dearborn Heights and Redford Township during wet-weather events. The history of rock tunneling in the area is associated with high groundwater inflows, artesian pressure, and hazardous and combustible gases. This paper presents the geotechnical considerations for designing the 11.28-km (7-mile) long, 9.14 m (30-ft) finished diameter tunnel and its associated adits, chambers and shafts, including the discussions of geotechnical investigations, rock mass characterization, estimated groundwater infiltration during construction, and the selections of excavation methods and lining system based on anticipated ground behavior to be encountered.

Jan 1, 2008

By C. H. Perbix

[On Pier D in the Port of Long Beach, California, the Port of Long Beach has built a new bulk cement distribution terminal. The facility is operated by Pacific Coast Cement Corporation, who designed the complex and leased it from the Port of Long Beach on a 40-year lease. At one bulk cement is unloaded from vessels carrying from 12,000 to 30,000 t. The unloading is performed with pig speed mechanical unloading equipment and delivered into a concrete silo complex with, a capacity of 50,000 t. From the silos, bulls cement is loaded into trucks for delivery. The facility was completed in September 1981.]

Jan 1, 1983

By Y. C. Kim

An alternate development drilling strategy to the one currently in use at the nine was investigated using geostatistics for a portion of the pit. The study area consisted of 4,000' x 5,000' in plan and 1,080' in elevation. The massive orebody, the three-dimensional nature of the problem, and the location of ultimate pit limit in the study area all created some unique problems in devising the development drilling strategy, as compared to the two-dimensional tabular deposits such as coal deposits. Rather than using the confidence interval of the global reserve estimate as the main criterion for development drilling, the confidence interval of short and medium range mine planning blocks was used as the objective. Based on somewhat arbitrarily selected level of confidence, the results from this study showed that a total of 50 DDHs rather than the planned 62 DDHs is sufficient in the study area, if the selected confidence levels are acceptable to the management. This paper also emphasizes the importance of the particular objectives being used in development drilling and how they influence the "optimai" place- ment of the development drill holes.

Jan 1, 1981

By S. H. Jason Choi

The Systems Conveyance and Operations Program (SCOP) is being implemented to convey tertiary-treated effluent to Lake Mead near Las Vegas, Nevada. The Reach 3 Tunnel Project is part of SCOP. The tunnel?s planned location along and across the Las Vegas Wash creates challenging tunneling conditions. A number of feasible excavation and initial support methods are being considered during the final design stage. This paper describes how the tunnel construction options were refined based on anticipated tunneling conditions and compatibility between tunnel excavation and initial support methods. A brief description of the most significant characteristics of the anticipated ground conditions is included for the purpose of discussion.

By G. L. Schroeder, C. H. Summers, D. B. Lindsay

INTRODUCTION The requirement that is placed on owners and operators of underground mines to protect workers against the health hazard of inhaling radioactive materials which are short-lived decay products of 222Rn can be satisfied by applying a considerable variety of what we may call "engineering" solutions as well as a number of "administrative" remedies to the problem. The most obvious of the "engineering" approaches has always been that of forced ventilation, in which relatively clean (i.e., radon-free) air from aboveground is drawn or pushed through the mine workings by a system of fans and ducts. This relatively clean air, in sweeping through the drifts, stopes and haulageways, dilutes the radon and radon-daughter concentrations in the air of the mine, and performs the added beneficial function of removing the daughter-mixture quickly enought to limit grow-in of the longer-lived nuclides in the group that make up the "toxic trio" on which the Working Level (IM) unit is based. Effective as the dilution-ventilation method is for control of WL in most underground mining situations, however, the increasing strictness of control measures that have been imposed on the mining industry over the last two decades have demanded measures of even greater effectiveness. In times of poor markets for yellow-cake and other products of the mines, mine operators are pressed to reduce operating costs, and the installation of additional primary ventilation capacity can be a severe burden on a mine that is already laboring under an unfavorable earning power. When traditional dilution-ventilation systems alone cannot meet the requirement for WI, control, radiation safety engineers and ventilation engineers begin to look at alternatives and auxiliary methods. Since the radon which produces the toxic daughter products originates in the rock of the mine walls, and since, in most United States mines, that rock is a porous sandstone through which air can move under the effect of atmospheric pressure gradients, and through which radon can diffuse relatively freely, one way to help control the growth of WL would be to hinder the escape of radon from that reservior of porous rock. An appealing; method for hindering that natural flux of radon-polluted air from the walls of the mine has long been apparent; namely, to apply a low-permeability coating over the surface of the rock, thus sealing the radon in place and, in theory at least, preventing its escape into the mine air. Our 1970 report to the U.S. Federal Radiation Council on the subject of cost impacts of proposed changes in the occupational standards for exposure of underground uranium miners to airborne radon daughters noted the possibility of using polymeric wall sealants as a means of controlling radon-pollution of mine air. Since that time a number of reports have appeared in the technical literature advocating this technique for restraining the escape of radon from building materials, mill tailings, and other materials containing 226Ra, in addition to the surfaces of underground mine workings. During this period, some controversy has occurred over the question of the probable effectiveness of wall sealants in limiting the escape of radon from the rock. Our 1970 report speculated that flaws (cracks and "pinholes") in the coating might be all but unavoidable in practice, and that even a conservative estimate of the frequency of such flaws would lead to a prediction of ineffectiveness. Hammon et al, in a laboratory evaluation of radon sealants conducted by Lawrence Livermore Laboratory of the University of California in 1975 on behalf of U.S. Bureau of Mines, concluded that a wide variety of polymeric coatings would provide "nearly 100% effectiveness" in restrain¬ing escape of radon from mine wall surfaces if applied in "thicknesses between 5 and 10 mil" (125-250 [y]pm). John Franklin and co-workers at the U.S. Bureau of Mines laboratories in Spokane, Washington, have carried the experiments with polymeric sealants through additional laboratory tests and into actual mine environments, reporting that selected sealants could provide attenuation of radon flux by a factor of four (75-80% reduction). Robert Bates and John Edwards of USBM developed a computer-assisted mathematical/physical model that predicts a relatively small effect of flaws in a low-permeability coating on the radon flux from a sandstone-type matrix. FIELD TEST Since all actual experimental work with wall sealants showed some beneficial effect on radon attenuation (even if not as exciting as the "nearly 100%" predicted by Hammon), USBM was encouraged to extend its evaluation to an actual operating uranium mine, and awarded a contract for that work to Arthur D. Little, Inc. in September 1979. We were fortunate in obtaining the voluntary cooperation of Atlas Minerals Division of Atlas Corp., who operate a mill and several underground mines in and around Moab, Utah. Atlas made available for our use a small T-shaped drift in their Pandora Mine in LaSal, Utah, and provided space for instrumentation and recordkeeping by our field crew in a surface building near the mine entry. Atlas also provided electricity and water to the test site, together with assistance in establishing necessary ventilation, removing rubble from the site, conducting periodic WL surveys and furnishing auxiliary man-power for the heavy hard work of coating the walls with gunite prior to application of the polymeric sealant. The generous coopera-

Jan 1, 1981

By Richard E. Ray

INTRODUCTION Main mine fan installations at underground coal mines must be designed to comply with the requirements outlined in 30 CFR (Code of Federal Regulations) Part 75. However, very little emphasis is typically placed on the aerodynamic optimization of shaft collar designs, ductwork configurations, and the selection of a fan isolation, or "closing door," system. Field testing has shown that poorly designed systems may produce large pressure losses between the shaft and fan inlet, as well as air turbulence problems which adversely impact fan efficiency and sometimes fan structural integrity. This paper analyzes each component of a surface exhaust fan system for an underground coal mine: • The shaft collar arrangement, • The 45 or 90-degree turning duct that isolates the fan motor from the return airstream, • Alternative ductwork arrangements for parallel fan installations, • The self-closing doors or dampers that are required for multiple fans, and • Horizontal and vertical evas6 arrangements on the discharge side of the fan. While discussion is limited to axial fan installations at shaft mines, most of the recommendations would also apply to centrifugal fan installations and to main mine fans for drift mines. FEDERAL REGULATIONS The mandatory safety standards for underground coal mines that apply to the installation of main mine fans are listed in 30 CFR Part 75.310. Stipulations which impact the design of the fan sys- tem arrangement are contained in paragraphs (a)(l), (a)(5), (a)(6),(d), and (1) of 75.31 0: • Each main mine fan shall be installed on the surface in an incombustible housing; • Each main mine fan shall be protected by weak walls or explosion doors in direct line with possible explosive forces; • Explosion doors or weak walls shall have a cross-sectional area at least equal to the area of the return air shaft or drift opening through which the pressure from an underground explosion would be relieved; • Each main mine fan shall be offset by at least 4.57 m (15 feet) from the nearest side of the mine or shaft opening; • Automatic closing doors shall be provided to prevent possible air reversals through the fans in mines ventilated by multiple main mine fans. The installation of main mine fans underground is prohibited by 30 CFR Part 75.310, (a)(l). Providing explosion doors or weak walls in line with a possible underground explosion and offsetting the fan 4.57 m (1 5 feet) from the edge of the shaft preclude the installation of the fan directly over the shaft. In addition, 30 CFR Part 75.507-1 specifies that all electrical equipment used in return air courses be permissible, which requires locating the fan motor outside of the airstream exhausted through the fan. To comply with the Part 75.310 regulations, explosion doors are typically located directly over the shaft as part of the shaft cover or 'bonnet." A sufficiently long section of ductwork placed between the shaft enclosure and fan, equipped with a 45 or 90- degree turn, enables the fan to be offset at least 4.57 m (1 5 feet) from the shaft and the motor to be isolated from the airstream. The need for the turn in the ductwork can be eliminated by driving the fan from the discharge side, instead of from the inlet side, and providing for a 90-degree bend in the evas6. For multiple main mine fan systems, self-closing doors can be located on the inlet or discharge side of the fan. FAN SYSTEM COMPONENTS A poorly designed exhaust fan arrangement will produce turbulent conditions at the fan inlet and significant pressure losses between the shaft and fan. Field tests have shown that pressure losses through inlet ductwork at some installations may constitute as much as 30 percent of the total mine head. Unfavorable flow conditions may cause a change in the operating point on the fan performance curve, resulting in reduced fan efficiency and pres- sure generation capability. In some instances, poor airflow distribution through the fan may create mechanical stresses that lead to fan blade or fan housing fatigue failures. The objective in designing an air duct arrangement for a fan system is to provide a low cost duct that will move the air from the shaft to the fan in a uniform air distribution and with minimum energy requirements. The optimum solution is a compromise between technical and economic factors. Aerodynamic design considerations for the shaft collar and cover, fan inlet ductwork for both single and parallel fans, self-closing doors, and evas6 are discussed in the sections below. Shaft Collar/Cover To prevent excessive turbulence and non-uniform air distribution through the fan, a smooth transition for the change in direction of airflow at the top of the shaft must be provided. However, the concrete lining of the shaft is abruptly terminated at the surface at many coal mine installations (see Figure I), creating a sharp 90-degree bend. The airflow exiting the shaft becomes heavily concentrated in the upper portion of the horizontal fan in-

Jan 1, 1997

By Ralph W. Barbaro

This paper presents a cyclic queueing model which evaluates the productivity of a shovel-truck materials haulage system. For a cyclic queueing problem with exponentially distributed service times, a cyclic queueing model provides exact solutions in a fraction of the time that simulation takes to produce an approximate solution. The model is applied to an example problem, and the results are validated with simulation. Simulation is used to show that the assumptions of exponentially distributed service times and steady-state are not serious problems. A cyclic queueing model can be used to quickly obtain an accurate assessment of the productivity of a shovel-truck system.

Jan 1, 1986

By R. W. Ballmer

Prior to initiating construction of a new mineral development project, sponsoring organizations must be convinced that the operation will be viable. Proof is typically provided by the feasibility study. Considerable man hours will be spent in assessing and evaluating data on the deposit, its environment, and the means of development. Impact studies must be made for various scales of operation, inclusion of by-products, new methods of treatment, deferent levels of integration, and infrastructure configuration. Examples of current materials handling cost estimates are provided from the ongoing investigation in which Amoco is a participant at Ok Tedi in Papua New Guinea and Gag Island in Indonesia.

Jan 1, 1979

By John F. Parmeter

On August 29, 1989, the Department of Labor, Mine Safety and Health Administration (MSHA), published a Federal Register concerning a new proposed rule on air quality, chemical substances and respiratory protection standards. As of this writing, their proposed rule has not become a standard. However, with little revision it could be expected to become a standard, and we in the mining industry will be expected to adhere to and enforce it.

Jan 1, 1991

By J. M. Wempen, M. K. McCarter

"Differential Interferometric Synthetic Aperture Radar (DInSAR) is a satellite-based remote sensing technique capable of measuring centimeter-level surface displacement with high spatial resolution over large areas. Regular monitoring of subsidence due to underground mine development is one potential application of DInSAR, and in this study, the application of DInSAR for subsidence monitoring is evaluated for two mining regions in the mountain west of the United States. In general, DInSAR has potential to identify the shape and extent of subsidence; in some cases, magnitudes and rates of subsidence can be defined. Importantly, the effectiveness of DInSAR for subsidence monitoring depends on the radar band (wavelength), the subsidence rate and the time between image acquisitions, and the topographic and vegetative surface characteristics. INTRODUCTION Differential Interferometric Synthetic Aperture Radar (DInSAR) is a satellite-based remote technique that can be used to measure small surface displacements. Under good conditions, centimeter-level displacements can be measured with subcentimeter accuracy (Buckley, 2000; Massonnet and Feigl, 1998). Additionally, DInSAR data have relatively high spatial and temporal resolutions. Pixels in Synthetic Aperture Radar (SAR) images can have a ground resolution as small as about 3 m, and images often include tens to hundreds of thousands of pixels and cover tens of kilometers. Regions are imaged regularly, and periods between images typically range from weeks to months. In DInSAR, phase measurements from two radar images acquired over the same region at different times are used to precisely measure relative distances (Rosen, 2014). Surface deformation, topography, and changes in the satellite position all contribute to differences in the length of the path that the radar wave travels in each image. SAR sensors use radar with relatively long wavelengths; L-band (24 cm wavelength), C-band (6 cm wavelength), and X-band (3 cm wavelength) radar are used most commonly. Because the wavelengths are long, small changes in the path length of the radar signal can be quantified by measuring the change in the phase of the radar signal between the images. In general, changes in the path length due to changes in the satellite position and topography are known or can be estimated, and centimeter-level changes in the path length due to deformation are measurable. This study evaluates the effectiveness of DInSAR for measuring subsidence in two mining regions in the mountain west of the United States. L-band data from the Advanced Land Observing Satellite (ALOS) and X-band data from the TerraSAR-X mission are evaluated. Imaging characteristics, including the radar band and the time between image acquisitions, are important for effective subsidence monitoring."

Jan 1, 2017

By Gabriel de Almeida

INTRODUCTION The widespread use of desktop computers by an ever increasing number of people, both for personal and for business and government uses, has brought public attention to surprising stories about computer abuse. Before the advent of microcomputers in the information processing environment, hundreds of amazing misdeeds involving large computers had already been reported, most of them perpetrated by highly skilled professionals. The undreamed enlarging of microcomputer potential has steadily posed a major threat to complex mainframe computing systems, as joyful teenagers become familiar with the habit of hacking around someone else's large processing system, by means of makeshift phone communication networks, based on their intended homework for personal computers -- for the sheer fun of it. Now, the never ending capacity and speed improvement of commercially available micros has given rise to a brand new concern for society: the hazards of processing sensitive information in the powerful, but still unsafe microcomputer itself, whether or not linked to other micros or mainframe networks. This paper deals with some aspects of the problems and presents some practical hints as to enhance protection and minimize risks to sensitive and secretive information when processed on microcomputers. The physical considerations of computer security and pertinent safety precautions will not be discussed, because while essentially relevant to information protection, recommendations are well defined by processing resources suppliers and their importance is more widely recognized by users in general. Definitions and Classifications. The following definitions and classifications will be considered in this report: Information Assets: Any knowledge or information processing, storing or conveying device displayed in one's environment. It consists of two main categories: INFORMATION RESOURCES: End user's application data wherever recorded. PROCESSING RESOURCES: EDP skilled user's hardware, software, peripherals, magnetic media, communication devices, auxiliary equipment, supplies and related operational procedures. Information Protection: In a broad sense this is the set of necessary procedures to assure to the legitimate user the effective control of the operation and allow modifications of information assets, so that their physical or cognitive integrity be preserved or any unexpected loss minimized inspite of accidental occurrences or intentional actions. Classification Processes: Commonly two classification processes are used to define key terms in information protection: SENSITIVE CLASSIFICATION: Pre-defined standards for assessing the vulnerability to losses due to lack of proper processing continuity if information is destroyed, disclosed, secluded, or misused. SECRECY CLASSIFICATION: A spectrum of degrees as to the expectancy of holding exclusiveness of unique information whose destruction, disclosure, seclusion or misuse will cause a negative impact on the legitimate holder environment. Sensitive Information: Any knowledge whose destruction. disclosure. seclusion or misuse - - - implies losses to its legitimate holder. It may be classified as: VITAL INFORMATION: An essential knowledge whose lack of proper availability implies total loss or termination of p

Jan 1, 1987

By David A. Holmes

After a century of variable government-supplied housing on their cold, windswept lands, and facing extremely limited natural resources and no timber, the Standing Rock Sioux Tribe has launched a study into alternative housing approaches for their people. Considering that they have little more than the soil and limited river aggregates under their feet, the Tribe has elected to consider adobe and earthen-wall construction. Earthen construction is no stranger to the Sioux lands. Smaller tribes, including the Mandan, Arikira, and Hidatsa, lived here among the Sioux in earthlodges for centuries. Such earthlodge structures were not unlike the Southwestern jacal style-a framework of upright branches and branches covered with mud-employed by the Anasazi about A.D. 700-900. Indeed, the Sioux people themselves evolved from earlier earthlodge dwellers. Indigenous peoples in New Mexico, Arizona, and neighboring Mexico have used earthen-wall housing for many centuries, reinforcing Sioux observations that this is today an earth-friendly, cost-effective, and practical approach. The Cheyenne River and Pine Ridge Sioux Reservations also recently have conducted studies on earthen- wall construction. This paper describes the search for and evaluation of potential raw-material resources for earthen-wall/adobe construction on the Standing Rock Reservation in North and South Dakota. Significant resources of clay/silt materials (8 million tons in the Striped Cloud clay bed) suitable as adobe binders and sand-and-gravel aggregate (2.5 million tons) that could support earthen/adobe construction have been identified throughout the Fort Yates Flat area on the Reservation. Also addressed is how adobe and rammed-earth construction could add to the diversity of reservation construction and address future Tribal housing and other building needs.

Jan 1, 1999

By D. L. Kowal, P. J. Whittaker, M. A. Tuzun, N. O. Lotter

The area of flotation testing of drill-core is important in the business plan of most mining companies. Metallurgical information derived from this practice can be used to advantage in strategic decision-making. Sampling, flotation testing and subsequent Qem SCAN analysis of a mineral resource is one example of this approach. Anew resource, located in Sudbury, Ontario, is being assessed for the Sudbury Operations of Falconbridge Limited, which includes the Strathcona Mill. In this case, it was possible to improve the value of information from sampling and flotation testwork by using an improved, statistically-based test design, by sampling the resource by generic end-member ore type, and by integrating the Mineral Processing and Mineral Science disciplines into a Process Mineralogy team. In addition to producing standard metal grade and recovery information, this new approach provides more reproducible information from representative samples and flotation testing in a replicate format. Qem SCAN technology is used to produce a size by size mineral balance, including both modal percentages and liberation, from which flotation models for each ore type can be developed. As a result, a key understanding of the potential behaviour of a given ore type, if mined and then processed at the current mill operation, is gained at the 95%confidence level. The three ore types of this mineral resource were shown to have different flotation characteristics. Quantifying the mineralogy and liberation in each of the three ore types, has shown that this difference is due to changes in modal percentages of ferro-magnesium and magnesium silicate minerals such as pyroxene, talc and serpentine. Liberation across the three ore types is very similar and is therefore not responsible for variation in flotation performance.

Jan 1, 2003

By J. Darlington, A. K. SenGupta

Water-swellable layered silicates, namely, the smectite clays can remove suspended materials (called herein as debris) and metal ions from aqueous streams. The present study shows that the flocculating and metal extracting abilities of smectite clay-based flocculants can be enhanced when these clays are used in conjunction with a specific anionic polymer. Such performance enhancement is attributed to the following: i) the clay-dispersing ability of the polymeric additive, that would translate into an increase in the clay-surface area available for the attachment of the debris particles onto the clay particles; ii) the possibility of dispersant-to-coagulant transition of the polymer during the later instants of the treatment process, as a result of reduction in solvency of the wastewater for the polymer due to the release of cationic species from the clay-based flocculant solids; iii) metal-complexing ability and adsorption properties of the polymer.

Jan 1, 2002

By Argenis Gamboa

The Arab community is formed by around twenty countries in Africa and Asia, linked basically by a common language-Arabic - and the same religion, the muslim. They jointly occupy around 12 million square kilometers with a total population of around 140 million people. Nevertheless, these nations differ widely in their geographic area and population. Thus, while Egypt has a territory of over a million square kilometers and a population of nearly 40 million people, Kuwait, Qatar and Bahrain have, among the three of them, less than 30, 000 square kilometers and a million inhabitants. The per capita income also vary greatly, depending on whether they are oil producing countries or not. Generally speaking, it can be said that these countries economies have been based on oil or agriculture and that in these last years, they have been making serious efforts to increase their degree of industrialization and have greatly improved their infrastructure. This trend has resulted in the development of the iron and steel industry, which is still in a stage of primary development.

Jan 1, 1979

By A. D. Davis

Limestone-based material shows great promise for removal of arsenic from water. In laboratory tests, it has removed more than 95% or arsenic and more than 99% of cadmium and lead. In addition, the waste material appears to be suitable for recycling or disposal in an ordinary landfill. However, the efficiency of limestone for arsenic removal could be improved. Recent research has shown that iron treatment of limestone can enhance its arsenic-removal efficiency greatly, increasing its attractiveness as an alternative to other methods.

Jan 1, 2012

By Taehong Kim, Changsoo (Kevin) Moon, Anil Parikh

"This paper presents an overview and performance evaluation for a reconditioned decades aged open type hard rock TBM utilized for the twin running tunnel excavations of the Second Avenue Subway Project in Manhattan, New York. The TBM tunnel lengths are approximately 2,370 m (7,800 ft, east TBM Tunnel) and 2,190 m (7,200 ft, west TBM Tunnel) with a 6.7 m (22 ft) bored diameter. This “senior” TBM mined through metamorphic rocks consisting of schist, granofels, and pegmatite, and encountered various adverse geological structures, including some relatively heavy groundwater inflows. The ground support was generally pattern friction rock bolts, and steel sets were used in poor ground. This paper presents TBM characteristics and the subsequent performance, such as machine utilization, downtime, cutter consumption rate, net penetration rate, and daily advance rate. Machine operating parameters including thrust, torque, gripping force, and cutterhead RPM, are compared with various accompanying ground conditions. The performance changes between the adjacent tunnel sections are also presented. INTRODUCTION Project Overview The Metropolitan Transportation Authority Capital Construction (MTACC)’s Second Avenue Subway (SAS) Program consists of four (4) phases from 125th Street to Manhattan Battery Park along the 2nd Avenue (see Figure 1) in Manhattan New York. As a part of Phase 1, Contract 1 was awarded to S3 JV (Skanska/Schiavone/Shea) to build a TBM launch box and subsequent twin TBM tunnels from 92nd Street to 63rd Street under 2nd Avenue. Contract 1 was one of the key contracts in Phase 1 to pre-excavate through the footprint of the follow-on underground stations (72nd St. Station, 86th St. Station, and 96th St. Station) by hard rock TBM excavation. The project team included Client MTACC, S3 Tunnel Constructors, Designer, Aecom-Arup JV, and Consultant Construction Manager, Parsons Brinckerhoff. The major elements of Contract 1 included construction of TBM Launch Box supported by secant pile and slurry walls and mining of twin TBM tunnels with a combined tunnel length of approximately 4,560 m (15,000 ft). The dimension of the TBM launch box was approximately 247 m (810 ft) long from 92nd Street to 95th Street, 21 m (70 ft) to 24 m (80ft) wide along the 2nd Avenue, and 18 m (60 ft) to 21 m (70 ft) deep from the ground surface. The launch box was later used for the follow-on 96th Street Station."

Jan 1, 2016

By Rei Arai, Yuta Yamamoto, Tetsuo Yamazaki, Naoki Nakatani

"Methane hydrate is of interest as an alternative energy resource in Japan and the R&D program has been ongoing for ten years (MH21: http://www.mh21japan.gr.jp/english/). Rare-earth element-rich deep-sea mud (REE Mud) is also of interest as an alternative resource in Japan and an exploration program has been launched in 2013.For methane recovery from the hydrate, a depressurization method pumps up water in a production well and has been successfully applied in field production tests (MH21: http://www.mh21japan.gr.jp/english/). However, micro-bubbles, which appear in the hydrate dissociation and water recovery processes may present an environmental issue. It may stick on clay and silt particles that accompany the recovered water, and may disturb settling of the particles in the water separation tank. For exploitation of REE Mud, an air-lift system has been proposed in the feasibility study (Abe et al., 2012). The same micro-bubble issue is expected during the air, water, and mud particle separation processes. In this research, the authors conducted a preliminary tank experiment for clarifying the effect of micro-bubbles on settling behavior of fine kaolinite particles. The behavior was continuously recorded by a still camera and the images were analyzed by the gray scale intensity. From the results the authors found a suspension effect for the settling of fine particles as the result of micro-bubbles. The effect should be studied in detail for preventing some serious environmental impacts during deep-sea mining."

Sep 1, 2014

By Benno Ring

"When designing segmental lining at a cross passage, modern solutions try to bear the loads transferred around the opening within the rings by using shear elements in the ring joints. Commonly used shear systems providing coupling are cam & pocket, shear keys, bicones and steel dowels. These solutions have advantages and disadvantages, but most importantly they have limits in their capacity to stabilize the lining at cross passages. With the help of 3D-FE-analyses for an opening of one segmental ring these different solutions are compared taking various ground conditions into account. As a result the capacity of the individual system is determined. Notice is made regarding the applicability of the system as well as the consequences for the design and the verification. INTRODUCTION The design of the lining at a cross passage is among the most difficult tasks when designing TBM-tunnels. At one time the bedding of the lining disappears due to the excavation behind the lining, at another the ring-structure is interrupted when parts of the lining are removed for the opening. The trick is to transfer the loads around the opening into other segments and to areas of the lining which are still supported by the ground. In the rings immediately at the cross passage this creates a distribution of forces within the segments that strongly deviates from that of the regular lining. The design needs to consider the boundary conditions of the respectively chosen solution for stiffening of the opening and its peculiarities in the modeling as well as in the verifications. In the past segments of steel or an internal strutting of steel (DAUB 2013) placed around the later openings were commonly used, see Figure 1. The application of a strutting from the outside to the rings is restricted to such circumstances when for example a connection from a shaft to the tunnel can be made in suitable ground conditions (Ring and Glomp 2012). Though steel segments provide a robust solution, they are expensive due to their laborious manufacture, the high proportion of construction steel required and the time consuming installation in the tunnel (Häfliger 2013). A strutting of steel requires extensive design and verification. The resulting structure usually weighs several tons and must be erected as well as demounted within the confined space of the tunnel, requiring suitable transport and assembly equipment. The cross section remains restricted, thus causing a bottleneck for TBM operations and hindering the works and installations for the cross passage works."

Jan 1, 2016

By D. Diekman

Perlite is not a trade name but a generic term for naturally occurring siliceous volcanic rock. A distinguishing feature which sets perlite apart from other volcanic glasses is that when heated to a suitable point in its softening range, it expands 5 to 20 times its original volume. This expansion is due to the presence of 2% to 6% combined water in the crude perlite rock. When quickly heated above 1600°F (871°C) crude perlite pops in a manner similar to popcorn. The combined water vaporizes and creates countless tiny bubbles in the heat softened glassy particles. It is these tiny glass sealed bubbles which account for the amazing lightweight and other exceptional physical properties of expanded perlite. The bulk densities of the expanded perlite generally range from 3 pounds per cubic foot (48 Kg M3) to 10 pounds per cubic foot (160 Kg H3).

Jan 1, 1985