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By Brian H. Jasperse, Nicholson Peter J.

Gravity retaining walls have been constructed using Deep and Shallow Soil Mixing (DSM and SSM) since 1991 in the United States. These walls, for both temporary and permanent uses, were constructed by mixing cement with in-situ soils over a volume containing 100% of the required gravity wall zone. Modern design techniques have reduced costs substantially by forming the required gravity wall section as a composite mass. Using ratios of 15-35% by volume, treatment f the ground forming the required gravity section has reduced the cost from about $40 to about $20 per square foot. Design, construction and actual performance of these gravity walls are presented.

Jan 1, 1999

By G. B. Quaye

The deep level gold mining environment is characterized by high stresses that give rise to intense mining induced fracturing of the rock mass surrounding the stopes. In a geologically disturbed region where the intensity of mining induced stress fracturing is high, the degree of faulting and/or the frequency of other geological features such as joints may pose serious strata control problems. Unfavourable intersection of these discontinuities namely, faults, joints and mining induced stress fractures tend to divide the immediate hangingwall into unstable keyblocks which, if not supported, may result in extensive falls of ground. Effective support strategies therefore demand detailed investigation of the predominant inclinations and orientations of these discontinuities. The orientations and inclinations of these discontinuities surrounding a deep level stope have been measured. The results are projected onto the lower hemisphere of a stereographic net to determine the factors that contribute to the falls of ground in the stope. The analyses reveal that unfavourable intersection of these discontinuities divides the immediate hangingwall into unstable wedges that may become dislodged between support units.

Jan 1, 1998

By G. A. Kosick, G. S. Dobby

"This paper presents the principles and application of a recently developed control system for flotation columns and column circuits. The control system uses triple pressure sensors to directly sense zone densities and level, and to help in characterizing the operating behaviour of individual columns. A complete expert system development tool is incorporated within the system to provide the facility for full operator training, an on-line help facility, and a means for incorporating the column behavioural patterns into decision making rules. The system is configurable to any number of columns and can be run in either supervisory mode or direct control through Minnovex PIO software. Additional process signals can be interfaced with the system if desired. Operating experience with the control system on the Minnovex column flotation pilot plant is described.I: INTRODUCTIONColumn flotation cells have been more difficult to control and are more sensitive to circuit changes than conventional mechanical flotation cells. This susceptibility encouraged investigation into various types of control strategies ranging from inexpensive single pressure measurements for level control, to highly instrumented and expensive systems using a variety of control methods.Flotation operators, in many cases, do not understand the column control philosophy or have not been trained to deal with this new type of cell. Some operators have subsequently absolved themselves of the column operating responsibility. Some column cells, for example, have run for hours with slurry pouring over the top or no froth coming off at all.ColumnEX is a column flotation control system which was developed from the viewpoint of an operating shift foreman who wishes to:1. control the column or column circuit through a genuine understanding of what is happening inside the columns, and2. to share this knowledge with his flotation operators and be available to guide them through times of circuit upsets."

Jan 1, 1990

By J. E. Sallee

An experimental study has been conducted on the level of arsenic contamination in samples of zinc oxide when the zinc oxide is contacted with gas mixtures containing As4O6(g). This contamination has been determined as a function of A4O6 saturation pressure, temperature, zinc oxide sample surface area, impurities, and oxygen level in the gas mixture. The results indicated a rather clean separation can be achieved between condensed zinc oxide and gaseous arsenic oxide as long as attention is given to temperature control, and the final zinc oxide surface area. For a 300°C operation temperature and an AqOg saturation pressure of 0.38 TORR (or 0.05% As406 by volume), the contamination level is expected to be approximately 100 ppm. This suggests that arsenical dusts can be treated in the HRD flame reactor process and a reasonable purity zinc oxideproduct produced. The results also show no evidence of zinc arsenite or zinc arsenate formation.

Jan 1, 1994

By Giovanni Lombardi

In order to get a clear overview of the grouting works carried out, to avoid misinterpretations of the data and functions shown on the display of the grout monitoring device, it is recommended to keep the flow rate as constant as possible. Obviously, at the beginning of the process, the flow rate will increase from nil to the selected "basic" value. An important question frequently addressed is also how to reduce the flow rate in nearing the GIN limit so to finally reach the target intensity. Depending on the actual conditions, there are different manners to proceed. However, the following one appears to be the most convenient. It is represented on Figure 25. Being GIN the target intensity, two new limits at, let's say, 0.95 GIN and at 1.05 GIN as shown in the figure should be defined. The selected basic grout flow rate "q0", is kept as constant as possible all along the grouting process until the 0.95 GIN limit is reached. The flow is then reduced step wise to 2/3 q0, 1/3 q0 and zero at crossing each of the three limits. A similar rule can be used in respect to the maximum pressure, while for the maximum volume the process can be stopped at one time. Obviously the number of successive limits and thus the number of steps in reducing the pressure, as well as the width of the fringes defined in said way may be adapted to the local conditions.

Feb 10, 2003

By L. M. Chan, D. H. Carlson, J. B. Johnson

"Abstract — Concentrations of tailpipe pollutants from diesel-powered. underground mine vehicles change over time due to engine wear and the need for maintenance. Since this deterioration in pollutant emissions may adversely affect the air quality in an underground mine, it should be monitored and controlled. This paper presents decision criteria concerning when to service a mine vehicle diesel engine. These criteria, based on mine air and tailpipe concentration measurements, are designed to maintain the tailpipe concentrations within limits that assure satisfactory mine air quality.Application of the deterioration criteria to mine vehicle emissions involves:establishing, for each pollutant, the allowable deterioration factor, anddetermining the deterioration factor, from the mine air and tailpipe diesel pollutant measurements, and the mine air threshold limit values (TLVs).If the deterioration factor is greater than or equal to the allowable deterioration factor the vehicle is removed from service for maintenance.An analysis applying the criteria to measurements made in an underground coal mine is presented. The tailpipe pollutant concentration data were collected using the Emissions Mea-surement Apparatus (EMA) developed by Michigan Techno-logical University. Since the TLV for diesel particulate matter (DPM) has not yet been established assumed mine air DPMTLVs of 15 and 1.0 mg/m3 were used in the analysis. For all of the diesel haulage vehicles included in the analysis. DPM was found to be the critical pollutant (the one most in need of control). For an assumed mine air DPM TLV of 15 mg/m3 none of the diesel haulage vehicles would he removed from service. However reducing the DPM TLV to 1.0 mg/m3 would make it necessary to remove two of the three vehicles tested from service."

Mar 1, 1992

By R. Harrisson, K. Esmaieli

Brunswick mine employs an ore and waste pass system for material transfer. This paper reviews the evolution and performance of ore pass systems at the mine. It presents the range of selected configurations, inclination, dimensions, etc. Select case studies are used to address the influence of structure, stress and materials handling on the longevity of the employed ore passes.

Jan 1, 2008

By K. Madhusudan Reddy

Pile response under combined uplift and lateral load is very important and it is imperative to evaluate the effect of combined loading and only few studies were reported on pile behavior under combined uplift and lateral loads. Model pile made-up of aluminum having an outer and inner diameter of 25.4 mm and 19.4 mm respectively is used. Dimensions of the model steel tank are fixed as 1.0 m x1.0 m x 1.2 m (depth) to avoid the boundary effects under combined lateral and uplift loads. Experiments were carried out on single piles at isolated uplift, isolated lateral loading and combined lateral and uplift loading, embedded in sandy soil. Results indicate that load?deflection behavior is nonlinear for isolated uplift and lateral load tests as well as in case of combined loadings. It is also observed that the behavior of piles under isolated loadings is substantially different when compared to combined loading.

By Frank E. Cash

The work of the United States Bureau of, Mines is concerned primarily with the prevention of accidents in the mining, petroleum, and allied industries. This report analyzes the fatal accidents in the coal mines of Tennessee and gives the pertinent factors in tabular and descriptive form, with interpretations and suggestions to operators, workers, and the State Division of Mines for the future prevention or reduction of accidents in coal mines. ACKNOWLEDGMENTS This study was made possible through the cooperation of A. W. Evans, chief mine inspector of Tennessee, and his secretary, Miss Hiliary Penny, who made available the department records and assisted in the segregation and assembly of the data.

Jan 1, 1935

By Ming Ju Liu

China has been suffering from the most serious coal and gas outburst accidents. The situation has become worse than ever with the mining of deeper coal seams at higher production rates in a more complex underground mining environment, in order to meet the huge national demand for coal-fuelled power plants. In the year 2007 alone, more than 30 outburst accidents occurred in underground coal mines with a death toll of 258, and in the year 2008, as of May 22, nine outbursts have already occurred in Henan, Hubei and Chongqing, killing 68 workers. At the same time, China also experienced new trends of coal and gas outburst accidents since its coal production boom in the year 2001. These trends are of great importance for government agencies, coal mine owners and operators to take initiative and effective measures to prevent and control the occurrence of coal and gas outbursts in China?s widely spread outburst prone mining areas. This paper presents outburst data of China coal mines since 2001 and describes new trends of outburst occurrence in recent years, which include outbursts coupled with shocks or rock bursts of competent roof, outbursts in mines under development, outbursts in new mines and mines that have never suffered outbursts before, outbursts in mines that are believed to be of low gas content as well as outbursts in more long-wall faces. Based on the observation of outburst occurrence in China in the period from 2001 to 2008 as well as mining and geological conditions, detailed analysis of the possible causes that led to those new trends of outburst accidents is conducted. The analysis helps shed light on possible future remedies and the necessary measures to alleviate or eliminate outburst accidents in underground coal mines. Suggestions are put forward on future studies that could be of interest to national and provincial government agencies regarding strategic policies, proper technical management practice, identification of outburst prone coal seams, online monitoring of impending outbursts as well as prevention and control measures.

Jan 1, 2008

By Yvette Heritage

"The risk of fatalities from rib failure is still prevalent in the coal mining industry. This risk has prompted further research to be conducted on rib deformation in order to understand the mechanisms of rib failure, with the long-term objective being to improve rib support design. This paper presents the results of ACARP research project C25057, which investigated the mechanics and drivers of rib failure. The results of rib deformation monitoring at three different mines in Australia provides rib deformation characteristics for overburden depths ranging from 160 m to 530 m. Monitoring includes deformation during development drivage conditions and during the longwall retreat abutment stress environment. The rib deformation monitoring covered three different seams: the Goonyella Middle Seam, Ulan Seam, and Bulli Seam in the Bowen Basin, Western Coalfield, and Southern Coalfield, respectively. The observed mechanisms driving the rib deformation ranged from bedding shear failure along weak claystone bands to vertical shear fractures to kinematic failures driven by shear failure dilation. The variation in mechanisms of rib failure, together with the seemingly consistent method of rib support design, prompts the question: What exactly is the role of rib support?INTRODUCTIONThe current risk of rib fatalities in the coal mining industry has prompted further research into understanding the mechanisms of rib failure. Three Australian mines assisted further research by providing sites for rib deformation studies as part of the Australian Coal Association Research Program (ACARP) project C25057. The mines included in this study were Moranbah North Mine, Ulan West Mine, and Appin Mine. This paper provides key results of the rib deformation monitoring relevant to assessing the mechanisms of rib deformation.The approach of monitoring rib deformation and rib support loads was used to measure and characterise the dynamic rib deformation present in both development and longwall retreat stress environments. The characterisation of rib deformation, together with rock failure modelling, was used to determine the mechanisms for failure within the rib and to assess the interaction of rib support with the failure process. The mechanisms of rock failure are considered an important factor in understanding the drivers for the failure. Consideration of the site-specific failure mechanisms can provide for a more tailored support design."

Jan 1, 2018

By P. R. Gage, R. W. Bartlett

At high temperatues and reduced oxygen pressuves, molybdenum silicicles oxidize to form SiO(g) vathev than a passivating SiO2 film. This is a sevious problem for low-pressure applications of sili-cide-coated rejvactory tnetals. As oxiclalion pvoceeds, the higher oxidntion potential of silicon initially suppresses oxidation of molybdenum and silicon is depleted near the surface. Eventually, silicon depletion causes secondary passivation (SiO2) mid an active to passiue transition in oxidntion behavior at moderately low pressures. At very low pressures, silicon depletion continues until steady-state oxidation of both silicon and rnolyhdenum can proceed at rates propovtional to their initial stoicliiorrzetvies. Ohsel-vations of 'oxidatiou-rate belzcriliov at temperatures from 1101° to 1700°C and oxygen pressures from 10-7 to 1 at in were made using thermogravimetn'c, X-ray diffraction, and elect?*on-rtric?ro/,vobe techniqrres. The experimental results are in good agreement with calculated lirnits for the various types of behavior that were based on tlievtnochernicnl atzd dffusion rate data for the Mo-Si system. A protective oxide film normally forms during the oxidation of elemental silicon. However, at elevated temperatures and reduced pressures this film is not present and oxidation is rapid. wagnerl has shown that this behavior occurs because SiO(g) is more stable than SiO2. The behavior of the silicides at high temperatures is similar but more complicated. Molybdenum and several silicide compounds are involved and the chemical activity of silicon, or the equivalent silicon vapor pressure, can vary considerably in these phases. Also, diffusion in the silicides resulting from reactions in which a higher silicide is reduced to a lower silicide, or molybdenum containing dissolved silicon, must be considered. EXPERIMENTAL AND ANALYTICAL METHODS Isothermal oxidation experiments were conducted using hot-pressed MoSi2 and Mo5Si3 wafers. Each experiment was conducted at a fixed oxygen pressure by controlling the flow of oxygen in and out of the furnace chamber. Most of the experiments were conducted in a molybdenum-wound tube furnace. Special construction features, including use of a high-purity dense A12O3 refractory tube, permitted operation in high vacuum to 1500°C. Higher temperatures could be obtained at higher working pressures and with a sacrifice of tube lifetime. Temperature was measured with three Pt 6 pct Rh/Pt 30 pct Rh thermocouples and controlled with a proportional controller. Weight changes were monitored with a quartz spring balance. The few experiments, at higher temperatures and low pressures, were conducted in a cold wall vacuum chamber using induction heating with direct susceptance of the sample. Because of the variable levitation effect of the induction coil on the sample, weight changes could not be monitored continuously in these experiments. All samples representing both experimental methods were weighed before and after oxidiation and examined with a microscope and analyzed by X-ray diffraction. The analytical treatment assumes equilibrium at interfaces and uses existing thermodynamic data. For convenience, equilibria are expressed as chemical potentials or as vapor pressures of the gases involved. The resulting differences in equilibrium vapor pressure between adjacent interfaces and between the surface and external atmosphere drive diffusion processes in the solid and gas boundary film, respectively. These diffusion processes govern the rate of oxidation. A bibliography of the sources of thermochemical data for the reactions pertinent to the Mo-Si-O system is given in Table I. Reactions are listed with the sources of free-energy data referenced. Since all of these reactions involve one or more gas species, usually oxygen, a plot of the product-gas chemical potential, -RT In Pg, vs absolute temperature for each reaction is given in Fig. 1. These curves can be used to determine equilibrium vapor pressures or to compare the stability of different compounds in the various gases: O2, Si, SiO, and Moo3,. The data of Table I and Fig. 1 were used to determine the analytical results presented in this paper. EXPERIMENTAL RESULTS The weight changes for three MoSi, samples oxidized at 1500°C are plotted against time in Fig. 2. The treatments were identical except for the indicated variance of oxygen pressure and each curve represents one of three characteristic types of behavior that were observed. The upper curve is an example of passive oxidation, which is defined as

Jan 1, 1965

This paper presents a case study where Cenozoic age detritals and an ancient buried landslide have been modelled in the final walls of an iron ore pit. Orebody 25 is located in Western Australia’s Pilbara region and is an operating pit where a redesign of the final wall cutback was required. The existing slope design utilised a simplistic geological model of mixed conglomeratic, calcretic and clay –dominated detritals overlying deformed bedrock sequences. This simplicity resulted in a conservative design that was not reflective of the slopes performance to that point. Further field investigation was carried out with the results assessed in conjunction with historic drilling, mapping and laboratory testing. A detailed geotechnical model was developed including three conglomerate and two clay dominated units and laterstage calcrete overprinting. The clay units were of significant importance to the stability assessment and resulting slope design due to the thickness and poor strength conditions indicated by the laboratory and field testing. However, the drilling investigation shed only limited understanding as to the origin of the clays and thereby how they should be treated as a component in the stability analysis. A comparison of the ratio of various geochemical elements measured by assay was made between the clays and 1) shale bedrock and 2) clays of known detrital origin from other nearby sites. This indicated the clays had a strong affinity with weathered bedrock. This and other textural features resulted in the interpretation that the clay units were relic debris preserved following ancient landslides in bedrock shale. Using laboratory testing data and calibration of results for a landslide origin, stability analyses were run, resulting in a steeper slope design being implemented. Excavation of the final cutback is now in progress with the model confirmed as appropriate.

Jan 1, 2015

By Jorge Alberto Soares Tenório, Flávia Paulucci Cianga Silvas, Denise Crocce Romano Espinosa, Ivo André Homrich Schneider, Erika Gusmão, Daniella Cardoso Buzzi, José Roberto de Oliveira

"This study evaluated the Salvinia sp action on metals biosorption in a synthetic sample of acid mine drainage (AMD) in order to determine the time and amount of metals uptake. Biosorptives tests were realized varying the contact time of 5, 20, 60 and 240 minutes. And keeping constant the follow parameters: pH (2.6), biomass concentration (1g.L-1), temperature (25°C) and agitation (175rpm). In order to quantify the metals concentration captured by biomass, the AMD samples will be analyzed by ICP. Biosorbent, Salvinia sp., will be characterized before and after the biosorptives tests through analysis of SEM and IR. The micrographs indicate the occurrence of micro-precipitation and changes in biomass physical structure. The infrared spectra indicate changes in functional groups present in the biomass before and after the biosorptives tests.IntroductionThe current emphasis on environmental sustainability leads the industry in general, to treat their waste. The human activities are increasing, highlighting the industrial and mining activities, and have promoted the contamination of soil, waterways and groundwater by metals (1). The waste must undergo treatment processes aimed at reducing pollution, and therefore, less aggression ecosystems.This means the importance of studies of economic and effective methods to eliminate these metals from wastewater generated. The bioindicators are good investments in this area. The aquatic weeds are plants that inhabit swamps up from truly aquatic environments. They have several morphological and physiological adaptations that enable them to colonize the various aquatic environments. They are used as bioindicators of water quality and have also been used in decontamination of aquatic environments, production of biomass for livestock feed, fertilizers, soil and fish tanks (2)."

Jan 1, 2012

By Barrie Robb

Outline 1. Mackenzie Aboriginal Corporation (MAC) 2. ACR background 3. ?Learning from Experience? project - What - Why - lessons 3. How Industry could contribute to sustainable Aboriginal communities 4. Concluding words What is the Mackenzie Aboriginal Corporation (MAC)? ? Aboriginal owned ? Established construction capabilities ? Commitment to development of northern resources ? Partners have extensive experience

May 1, 2008

By Jan Dabrovska

Solidification and cooling of a continuously cast slab and simultaneous heating of a mould is a very complicated problem of transient heat and mass transfer. Nowadays, the solving of such a problem is impossible without numerical models of the temperature field not only of the slab itself, while it is being processed through the whole concasting machine (Caster), but of the mould as well. Two original numerical models have been developed and used in the investigation of a continuously cast steel slab. The first (one of two) 3D model of the temperature field of a concasting is capable of simulating the temperature field of a caster. Experimental research and data acquisition have to be conducted simultaneously with the numerical computation-not only to confront it with the actual numerical model, but also to make it more accurate throughout the process. After computation, it is possible to obtain the temperatures at each node of the network, and at each time of the process. The utilization of the numerical model of solidification and cooling of a concasting plays an indispensable role in practice. The potential change of technology-on the basis of computation-is constantly guided by the effort to optimize, i.e. to maximize the quality of the process. The user can therefore choose any appropriate longitudinal or cross-section of a slab and display or print the temperature field in a 3D or 2D graph whenever necessary. The second numerical model of dendritic segregation of elements assesses critical points of slabs from the viewpoint of their increased susceptibility to crack and fissure. In order to apply this model, it is necessary to analyze the heterogeneity of samples of the constituent elements (Mu, Si and others) and impurities (P, S and others) in characteristic places of the solidifying slab. The numerical model, based on measurement results obtained by an electron micro-probe, generates distribution curves showing the dendritic segregation of the analyzed element, together with the distribution coefficients of the elements between the liquid and solid states. The combination of both models enables the prediction of cracks and fissures in critical points of the continuously cast carbon-steel slab. Both models had been applied in the industrial investigation of a cast low-carbon-steel slab.

Jan 1, 2003

By G. A. Doyle

The White Pine Mine is the second-largest active underground copper mine in the United States, covering an area of approximately 13 square miles in the Upper Peninsula of Michigan. The mine operator intends to initiate in-stope solution mining by circulating a solution of mine water, sulfuric acid, and ferric iron through rubblized ore and recovering copper from solution. As planned, the solution would be retired in the mined-out stopes following completion of solution mining activities. Investigations into the fate of the retired solution mining fluid indicate that the solution, through time, will change from an acidic, metal-rich solution to a near-neutral, reducing solution containing much lower concentrations of metals. Investigations include reaction path modeling (EQ3/6) and laboratory and in-mine experiments. The combination of neutralization and reduction will result in precipitation of most metals, primarily as metallic sulfates, chlorides, and sulfides.

Jan 1, 1996

By Paul R. Wieber, Atam P. Sikri

This paper describes the U. S. Energy Research and Development Administration's (ERDA) program to develop in situ coal conversion processes, especially gasification. The potential of this technology, the technical directions being explored, and the program strategy to carry the process concepts toward commercialization are emphasized. The geographic location of the U. S. coal resources and a market analysis are described. Commercially successful in situ coal processes could add over a trillion tons of coal to the U. S. coal reserves. The economics of these processes is compared with surface gasification. Independent studies show this process to be 25% cheaper than surface gasification for Western coals. The major projects are briefly described. The Linked Vertical Well process is in the most advanced stage and shows great promise. The last test produced a low-Btu gas averaging 171 Btu per standard cubic foot for average production rates of 8.5 million standard cubic feet per day. The other projects are Packed Bed, Longwall Generator, and Steeply Dipping Beds. Unique factors of the process development are discussed which may lead to commercial processes in the near term. A development strategy is proposed by which this technology could be commercialized before 1983 with potentially lower gas prices and lower environmental impacts, relative to mining plus surface gasification.

Jan 1, 1979

By E. J. McLean

Gold mineralisation at Bendigo is exclusively associated with quartz reefs, commonly found within or near anticlinal fold hinges. The gold is typically coarse grained (0.5 mm to 5 mm), free milling and displays a complex, nuggetty distribution within the veins. This ore is highly amenable to gravity recovery processes. As the Bendigo operation is not permitted to treat whole ore by a cyanide leach/CIL circuit, the flow sheet is more complex than conventional gold recovery circuits. Primary gold recovery is from a gravity circuit closing the grinding circuit to a bulk gravity concentrate and from a flotation circuit treating cyclone overflow to a bulk float concentrate. The plant capacity is relatively low by current gold industry standards at 600 000 tpa. Re-establishing gold production at Bendigo has presented several challenging, and sometimes competing, issues in process design and operation. The mine, process plant, associated services and infrastructure are at Kangaroo Flat, a low density, semi-rural zone in the southern urbanisation of the Bendigo metropolitan area. One of the main processing challenges during the design was the competing comminution requirement to avoid over-grinding, which would flatten or smear the characteristic nugget gold and hinder effective gravity gold recovery, whilst also providing sufficiently well liberated particles that would respond well to flotation. Important, non-metallurgical challenges were to minimise impacts on the local community from noise, dust, air emissions, visual impact, water egress and off-site traffic.

Jan 1, 2007

By M Norbert, P Mok

The mainline running tunnels for Legacy Way comprise of two-lane tunnel boring machines (TBM) driven tunnels. The length of the TBM tunnel section is approximately 4.2 km. The TBMs employed are double shield TBMs. Typical support to the segment ring while advancing a double shield TBM comprises of filling the excavated annulus between the ground and the segmental lining by injecting pea gravel, followed with primary grouting to fill between the pea gravel some distance behind the excavated face. The methodology adopted for the Legacy Way project, however, did not follow this typical approach, instead, two component grouting of the annulus was carried out.Where the annulus is typically filled with pea gravel, support is provided to the segment ring very close to the end of the tail shield, whereas in the case of two component grout this is not practical as the risk of grouting in the tail shield is high. The staging of the two component grout injection, the grout early age strength properties become key issues in ensuring that the segment ring leaving the TBM tail shield is stable and can support the necessary external loads.Two-component grout is a grout with two components, cementitious grout (component A) and accelerator (component B), commonly adopted for earth pressure balance (EPB) TBM. The grout reaches its thixotropic state in a matter of seconds providing initial support for the segment rings. Manual injection of two component grout to fill the bore annulus was carried out in stages leaving a portion of the segment rings unsupported. Ring stability during TBM advance was provided by a combination of ram thrust and the segment circumferential joint shear connectors.This paper outlines the design considerations such as rock load derivation by probabilistic analysis carried out utilising the software JBlock, 3D finite element analyses using the software Strand7 for ring stability and the testing and back analysis of the shear connector load bearing behaviour. In particular, the actual available capacity of the shear connectors against their published capacity by supplier was discussed.CITATION:Mok, P and Norbert, M, 2014. Tunnel boring machine excavation stability – double shield tunnel boring machine advance with partially grouted annulus, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 51–62 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014