- Email: [email protected]
Transient loading-related settlement of a square foundation on geogrid-reinforced sand
REINFORCEMENT:EARTH
339A
Shotcrete
advantages gained from the application of this emerging technology. (Author)
957262 Durabilite des reparations en beton projete (Durability of shotcrete repairs) A. Lamontague, M. Pigeon & D. Beaupre, Materials & Structures, 28(179), 1995, pp 260-266.
957265 Dimeusionamiento y sostenimiento de minas subterraneas de pizarra (Dimension and support of underground slate mines) J. Taboada Castro, F. Gutierrez Blanco, C. Gonzalez Nicieza & J. Torano Alvarez, Cuadernos Laboratorio Xeoioxico de Laxe, 19, 1994, pp 419-435.
This paper summarizes various test results obtained at Laval University in recent years on this subject. In dry-mix shotcrete, the use of an air entraining admixture diluted in the water used for the shooting increases the deicer salt scaling resistance, because of a significant decrease in the air void spacing factor. The use of such admixtures, irrespective of the type or the dosage (between 10 and 40 ml 1"l water), does not modify the properties of shotcrete significantly except for its compressive strength. A higher dosage leads to a reduction in strength. For wet-mix shotcrete, the use of silica fume seems to bring the same advantages as those obtained in conventional concrete. The advantages are a decrease in drying shrinkage, an increase in the resistance to freeze-thaw cycles, and a small increase in the compressive strength. Also, it seems clear that the spacing factor of the air bubbles in wetmix shotcrete is very important for resistance to freeze-thaw cycles in the presence or absence of deicer salts. The bonding between good quality shotcrete mixtures (with and without steel fibers) and concrete surfaces prepared by hydrodemolition or chipping with jackhammers followed by sandblasting was found to be generally strong and durable. The other types of surface preparation (grinding, chipping with jackhammers
without sandblasting and sandblasting alone) resulted in either lower bonding strengths or a reduction in the bonding strength with time. (English summary) 957263 Ursachen und Gefahren you Staubentwicklung beim Trockeuspritzen (Causes and hazards of dust development during dry spraying) H. Micke, Felsbau, 13(1), 1995, pp 39-41. Tests under practical conditions have shown that dust development during the dry spraying process should not only be regarded as troublesome, but that it also conceals potential hazards. So far no advances have been made in suppressing the dust prodmxd by shotcrete in empirical procedures. The starting point for further development work is determined. It is necessary to aim for stable discharge form the nozzle and solution of the area problem in the spraying process. (English summary)
Direct rock support methods 957264 Pillar recovery using mobile roof supports A. J. Hewitson, Mining Technology, 77(885), 1995, pp 153160. Since 1991 Rox Coal has been using mobile roof supports (MRS) for retreat mining (pillaring) in a bid to improve productivity and safety, reduce costs and increase percentage extraction during this phase of the operation. MRS are basically self contained longwall shields on cat-tracks, operated by radio remote control and used sequentially to replace timber whilst retreat mining. The units have been successfully deployed in a number of mining panels with extracted seam heights ranging from 44 inches to 7 1/2 feet. Safety has been demonstrably improved and productivity rates have approached those of the best longwall installations. This paper demonstrates the philosophy behind this modus operandi, describes the mining operations, gives a technical description of the equipment and details productivity and cost
The dimensions and support of an underground mine of roofing slate in Galice, worked by rooms with continuous pillars was studied. The rock mass was characterized by the empiric and analitic methods, calculating the stable pillar wide along the mine by the theory of attributed area and by a model of finite elements, where the breaking criterion of Hock and Brown was applied. The result was a parabolic relationship between pillar wide and mine length. Stability studies in an isolated stope give an elastic performance on the periphery of the room, without tractions. Although the stability of the mine is good, a systematic support is recommended on the basis of bolts, that will be reinforced with projected concrete at the top, and a singular treatment of the detected wedges. (English summary)
Reinforced earth 957266 Specification profiles for nonwovens used in civil engineering K. Lieberenz, M. Magel & W. Kittelmann, International Textile Bulletin. Nonwovens/Industrial Textiles, 41(1), 1995, pp 16-20. This article outlines, with the use of examples, the multitude of end-use areas for technical textiles in the building industry. In some end-uses the combined action of soil and/or building materials and technical textiles is sufficiently understood to allow clear specification profiles for the manufacture of the textiles. However, often only empirically obtained information is available to help the engineer in the development of technical textiles. End-uses for such textiles include •tration, drainage, protection and stabilization in the form of geotextiles, and cladding, load-bearing and insulating in building construction. (T.King) 957267 Bearing capacity of rectangular footings on geogridreinforced sand T. Yetimoglu, J. T. H. Wu & A. Saglamer, Journal of Geotechnical Engineering - ASCE, 120(12), 1994, pp 20832099. The effects of the depth to the f'u'st layer of reinforcement, vertical spacing of reinforcement layers, number of reinforcement layers, and the size of reinforcement sheet on the beating capacity were investigated. Both the experimental and analytical studies indicated that there was an optimum reinforcement embedment depth at which the bearing capacity was the highest when single-layer reinforcement was used. Also, there appeared to be an optimum reinforcement spacing for multilayer reinforced sand. The bearing capacity of reinforced sand was also found to increase with reinforcement layer number and reinforcement size when the reinforcement was placed within a certain effective zone. (from Authors) 957268 Transient londing-related settlement of a square foundation on geogrid-reinforeed sand
B. M. Das & A. Maji, Geotechnical & Geological Engineer/rig, 12(4), 1994, pp 241-251.
340A
SURFACE STRUCTURES:GENERAL
Laboratory model test results are presented that determine the effectiveness of using layers of geogrids as reinforcement in sand to reduce the settlement of square surface foundations subjected to transient loading. The model tests were conducted with only one type of geogrid at one relative density of compaction of sand. The maximum intensity of the transient load applied always exceeded the static ultimate bearing capacity of the foundation when supported by unreinforced sand. The settlement reduction factors for various depths of reinforcement have been determined. (Authors)
957269 Influence of geotextiles on performance of saline sebkha soils S. N. Abduljauwad, F. Bayomy, A.-K. M. AI-Shaikh & O. S. B. AI-Amoudi, Journal of Geotechnical Engineering ASCE, 120(11), 1994, pp 1939-1960. Along the western shores of the Arabian Gulf, saline soils, known as sebkhas, are widely distributed. These soils are associated with many geotechnical problems that emerge principally because of their high salt content and their susceptibility to strength loss and collapse upon saturation. In this study the variables investigated included subbase thickness, level of stress, type of geotextile, and saturation effect. Results indicate that the use of geotextiles significantly enhances the inferior properties of sebkha subgrade. Results of the index laboratory tests on the small-scale model have been used by local municipalities for road constructed on sebkha subgrade in the eastern province of Saudi Arabia.
subsurface. It is necessary to develop a new standard method to determine the unsaturated hydraulic conductivity function of dense, clayey substrates. (Author)
Soil compaction 957272
Calibration and design optimization of a andear surface moisture-density gauge by Monte Carlo simulation I. F. Goncalves, J. Salgado, J. Neves & F. G. Carvalho,
Nuclear Geophysics, 8(6), 1994, pp 527-537. The application of analytical methods to the solution of radiation transport problems is not feasible for the complicated geometries found in most cases of practical interest. The design and calibration of a nuclear gauge can be successfully assisted by computerized Monte Carlo simulation techniques. This paper reports the results of numerical calculations obtained using the MCNP code to simulate a neutron-y-ray surface gauge for moisture and density measurements. Good agreement between experimental and calculated calibration curves has been obtained. An optimiTation study has been carried out to improve the gauge performance through an adequate choice of the spatial arrangement of gauge components and the utilization of shielding materials. (Authors)
SURFACE STRUCTURES
(from Authors)
General 957270 Physical and hydraulic properties of synthetic envelopes for subsurface drainage in Pakistan M. R. Choudhry, A. Khaliq, W. F. Vlotman & Habib-urRehman, Irrigation & Drainage Systems, 9(1), 1995, pp 7384. Seven envelope materials were tested in the laboratory with upward flow permeameters to determine their physical properties and hydraulic performance. The base soil was taken from the site of the Fourth Drainage Project, Faisalabad, Pakistan. The performance parameters included ratios of gradient and hydraulic conductivity of the interface of envelope material and base soil and the discharge through the permeameter. Each of the tested materials satisfied the particle-retention criteria as the ratio of characteristic diameters of envelope (09o) and soil (dgo) remained less than 2.5. The filter criteria, however, could not be met satisfactorily, particularly during receding hydraulic gradients, when the ratio of envelope and base soil hydraulic conductivities (Ke/ Ks) dropped b r o w 1, except in the case of one imported material. Blocking of the soil-envelope interface occurred due to the internal movernent of soil particles, particularly during receding gradients. (from Authors) 957271
Desiccation of mineral liners below waste disposal sites under the influence of temperature gradients P. Doll, in: Groundwater quality: remea~ation and protection. Proc. conference, Prague, 1995, ed K. Kovar & J. Krasny,
957273
Record breaking Troll gas platform towed into position D. Parker, New Civil Engineer (NCE), 1128, 1995, p 6. This article describes the Troll gas production platform, said to be the tallest ever reinforced concrete structure. The platform has successfully been positioned off the coast of Norway above Europe's biggest offshore gas field. The platform's innovative features are described, including the gas processing facilities which are at the land end of the connecting pipeline. This use of multiphase transport technology, where untreated mixtures of gas and liquids travel in the same pipeline, is claimed to be a first for the North Sea. (S.E.Brown)
957274 Canadian experience in open pit mining R. K. Singhal, J.-L. Collins & K. Fytas, Mining Engineering, 47(1), 1995, pp 58-61. More than two-thirds of the mines in Canada are surface operations. They produce the bulk of the country's iron ore, asbestos, coal, copper, lead, zinc and synthetic crude oil from oil sands. This article describes the mining methods, equipmerit, automation and computers, environmental issues and management associated with this type of mining (S.E.Long)
(IAHS; Publication, 225), 1995, pp 329-336.
957275 Zaldivar J. Chadwick, Mining Magazine, 171(5), 1994, pp 271-277.
The mineral bottom liner of a 7 years old municipal landfdl (without plastic liner) was sampled to assess the risk of desiccation and cracking of liners below warm waste disposal sites. Studies with a numerical model of coupled moisture and heat transport show that desiccation can only happen if a plastic liner or very dry waste obstruct the temperature gradient induced vapour transport from the waste to the liner. Whether desiccation actually occurs then depends on the distance to groundwater and on the unsaturated hydraulic conductivity functions of the mineral liner and natural
An overview of Chile's new Zaldivar copper mine. The process design features Nordberg WaterFlush crushers, a large thickener, and new patented vertical smooth flow (VSF) SX technology. The SX-EW plant will have an annual production capacity of 125 000 t. Geology of the deposit, open pit mining operations, crushing and classifying, heap leaching, the VSF solvent extraction technology and results from a pilot test unit, the 35m diameter Supaflo High Rate thickener, additional geological resource potential, and construction costs, are outlined. (J.M.McLaughlin)
339A
Shotcrete
advantages gained from the application of this emerging technology. (Author)
957262 Durabilite des reparations en beton projete (Durability of shotcrete repairs) A. Lamontague, M. Pigeon & D. Beaupre, Materials & Structures, 28(179), 1995, pp 260-266.
957265 Dimeusionamiento y sostenimiento de minas subterraneas de pizarra (Dimension and support of underground slate mines) J. Taboada Castro, F. Gutierrez Blanco, C. Gonzalez Nicieza & J. Torano Alvarez, Cuadernos Laboratorio Xeoioxico de Laxe, 19, 1994, pp 419-435.
This paper summarizes various test results obtained at Laval University in recent years on this subject. In dry-mix shotcrete, the use of an air entraining admixture diluted in the water used for the shooting increases the deicer salt scaling resistance, because of a significant decrease in the air void spacing factor. The use of such admixtures, irrespective of the type or the dosage (between 10 and 40 ml 1"l water), does not modify the properties of shotcrete significantly except for its compressive strength. A higher dosage leads to a reduction in strength. For wet-mix shotcrete, the use of silica fume seems to bring the same advantages as those obtained in conventional concrete. The advantages are a decrease in drying shrinkage, an increase in the resistance to freeze-thaw cycles, and a small increase in the compressive strength. Also, it seems clear that the spacing factor of the air bubbles in wetmix shotcrete is very important for resistance to freeze-thaw cycles in the presence or absence of deicer salts. The bonding between good quality shotcrete mixtures (with and without steel fibers) and concrete surfaces prepared by hydrodemolition or chipping with jackhammers followed by sandblasting was found to be generally strong and durable. The other types of surface preparation (grinding, chipping with jackhammers
without sandblasting and sandblasting alone) resulted in either lower bonding strengths or a reduction in the bonding strength with time. (English summary) 957263 Ursachen und Gefahren you Staubentwicklung beim Trockeuspritzen (Causes and hazards of dust development during dry spraying) H. Micke, Felsbau, 13(1), 1995, pp 39-41. Tests under practical conditions have shown that dust development during the dry spraying process should not only be regarded as troublesome, but that it also conceals potential hazards. So far no advances have been made in suppressing the dust prodmxd by shotcrete in empirical procedures. The starting point for further development work is determined. It is necessary to aim for stable discharge form the nozzle and solution of the area problem in the spraying process. (English summary)
Direct rock support methods 957264 Pillar recovery using mobile roof supports A. J. Hewitson, Mining Technology, 77(885), 1995, pp 153160. Since 1991 Rox Coal has been using mobile roof supports (MRS) for retreat mining (pillaring) in a bid to improve productivity and safety, reduce costs and increase percentage extraction during this phase of the operation. MRS are basically self contained longwall shields on cat-tracks, operated by radio remote control and used sequentially to replace timber whilst retreat mining. The units have been successfully deployed in a number of mining panels with extracted seam heights ranging from 44 inches to 7 1/2 feet. Safety has been demonstrably improved and productivity rates have approached those of the best longwall installations. This paper demonstrates the philosophy behind this modus operandi, describes the mining operations, gives a technical description of the equipment and details productivity and cost
The dimensions and support of an underground mine of roofing slate in Galice, worked by rooms with continuous pillars was studied. The rock mass was characterized by the empiric and analitic methods, calculating the stable pillar wide along the mine by the theory of attributed area and by a model of finite elements, where the breaking criterion of Hock and Brown was applied. The result was a parabolic relationship between pillar wide and mine length. Stability studies in an isolated stope give an elastic performance on the periphery of the room, without tractions. Although the stability of the mine is good, a systematic support is recommended on the basis of bolts, that will be reinforced with projected concrete at the top, and a singular treatment of the detected wedges. (English summary)
Reinforced earth 957266 Specification profiles for nonwovens used in civil engineering K. Lieberenz, M. Magel & W. Kittelmann, International Textile Bulletin. Nonwovens/Industrial Textiles, 41(1), 1995, pp 16-20. This article outlines, with the use of examples, the multitude of end-use areas for technical textiles in the building industry. In some end-uses the combined action of soil and/or building materials and technical textiles is sufficiently understood to allow clear specification profiles for the manufacture of the textiles. However, often only empirically obtained information is available to help the engineer in the development of technical textiles. End-uses for such textiles include •tration, drainage, protection and stabilization in the form of geotextiles, and cladding, load-bearing and insulating in building construction. (T.King) 957267 Bearing capacity of rectangular footings on geogridreinforced sand T. Yetimoglu, J. T. H. Wu & A. Saglamer, Journal of Geotechnical Engineering - ASCE, 120(12), 1994, pp 20832099. The effects of the depth to the f'u'st layer of reinforcement, vertical spacing of reinforcement layers, number of reinforcement layers, and the size of reinforcement sheet on the beating capacity were investigated. Both the experimental and analytical studies indicated that there was an optimum reinforcement embedment depth at which the bearing capacity was the highest when single-layer reinforcement was used. Also, there appeared to be an optimum reinforcement spacing for multilayer reinforced sand. The bearing capacity of reinforced sand was also found to increase with reinforcement layer number and reinforcement size when the reinforcement was placed within a certain effective zone. (from Authors) 957268 Transient londing-related settlement of a square foundation on geogrid-reinforeed sand
B. M. Das & A. Maji, Geotechnical & Geological Engineer/rig, 12(4), 1994, pp 241-251.
340A
SURFACE STRUCTURES:GENERAL
Laboratory model test results are presented that determine the effectiveness of using layers of geogrids as reinforcement in sand to reduce the settlement of square surface foundations subjected to transient loading. The model tests were conducted with only one type of geogrid at one relative density of compaction of sand. The maximum intensity of the transient load applied always exceeded the static ultimate bearing capacity of the foundation when supported by unreinforced sand. The settlement reduction factors for various depths of reinforcement have been determined. (Authors)
957269 Influence of geotextiles on performance of saline sebkha soils S. N. Abduljauwad, F. Bayomy, A.-K. M. AI-Shaikh & O. S. B. AI-Amoudi, Journal of Geotechnical Engineering ASCE, 120(11), 1994, pp 1939-1960. Along the western shores of the Arabian Gulf, saline soils, known as sebkhas, are widely distributed. These soils are associated with many geotechnical problems that emerge principally because of their high salt content and their susceptibility to strength loss and collapse upon saturation. In this study the variables investigated included subbase thickness, level of stress, type of geotextile, and saturation effect. Results indicate that the use of geotextiles significantly enhances the inferior properties of sebkha subgrade. Results of the index laboratory tests on the small-scale model have been used by local municipalities for road constructed on sebkha subgrade in the eastern province of Saudi Arabia.
subsurface. It is necessary to develop a new standard method to determine the unsaturated hydraulic conductivity function of dense, clayey substrates. (Author)
Soil compaction 957272
Calibration and design optimization of a andear surface moisture-density gauge by Monte Carlo simulation I. F. Goncalves, J. Salgado, J. Neves & F. G. Carvalho,
Nuclear Geophysics, 8(6), 1994, pp 527-537. The application of analytical methods to the solution of radiation transport problems is not feasible for the complicated geometries found in most cases of practical interest. The design and calibration of a nuclear gauge can be successfully assisted by computerized Monte Carlo simulation techniques. This paper reports the results of numerical calculations obtained using the MCNP code to simulate a neutron-y-ray surface gauge for moisture and density measurements. Good agreement between experimental and calculated calibration curves has been obtained. An optimiTation study has been carried out to improve the gauge performance through an adequate choice of the spatial arrangement of gauge components and the utilization of shielding materials. (Authors)
SURFACE STRUCTURES
(from Authors)
General 957270 Physical and hydraulic properties of synthetic envelopes for subsurface drainage in Pakistan M. R. Choudhry, A. Khaliq, W. F. Vlotman & Habib-urRehman, Irrigation & Drainage Systems, 9(1), 1995, pp 7384. Seven envelope materials were tested in the laboratory with upward flow permeameters to determine their physical properties and hydraulic performance. The base soil was taken from the site of the Fourth Drainage Project, Faisalabad, Pakistan. The performance parameters included ratios of gradient and hydraulic conductivity of the interface of envelope material and base soil and the discharge through the permeameter. Each of the tested materials satisfied the particle-retention criteria as the ratio of characteristic diameters of envelope (09o) and soil (dgo) remained less than 2.5. The filter criteria, however, could not be met satisfactorily, particularly during receding hydraulic gradients, when the ratio of envelope and base soil hydraulic conductivities (Ke/ Ks) dropped b r o w 1, except in the case of one imported material. Blocking of the soil-envelope interface occurred due to the internal movernent of soil particles, particularly during receding gradients. (from Authors) 957271
Desiccation of mineral liners below waste disposal sites under the influence of temperature gradients P. Doll, in: Groundwater quality: remea~ation and protection. Proc. conference, Prague, 1995, ed K. Kovar & J. Krasny,
957273
Record breaking Troll gas platform towed into position D. Parker, New Civil Engineer (NCE), 1128, 1995, p 6. This article describes the Troll gas production platform, said to be the tallest ever reinforced concrete structure. The platform has successfully been positioned off the coast of Norway above Europe's biggest offshore gas field. The platform's innovative features are described, including the gas processing facilities which are at the land end of the connecting pipeline. This use of multiphase transport technology, where untreated mixtures of gas and liquids travel in the same pipeline, is claimed to be a first for the North Sea. (S.E.Brown)
957274 Canadian experience in open pit mining R. K. Singhal, J.-L. Collins & K. Fytas, Mining Engineering, 47(1), 1995, pp 58-61. More than two-thirds of the mines in Canada are surface operations. They produce the bulk of the country's iron ore, asbestos, coal, copper, lead, zinc and synthetic crude oil from oil sands. This article describes the mining methods, equipmerit, automation and computers, environmental issues and management associated with this type of mining (S.E.Long)
(IAHS; Publication, 225), 1995, pp 329-336.
957275 Zaldivar J. Chadwick, Mining Magazine, 171(5), 1994, pp 271-277.
The mineral bottom liner of a 7 years old municipal landfdl (without plastic liner) was sampled to assess the risk of desiccation and cracking of liners below warm waste disposal sites. Studies with a numerical model of coupled moisture and heat transport show that desiccation can only happen if a plastic liner or very dry waste obstruct the temperature gradient induced vapour transport from the waste to the liner. Whether desiccation actually occurs then depends on the distance to groundwater and on the unsaturated hydraulic conductivity functions of the mineral liner and natural
An overview of Chile's new Zaldivar copper mine. The process design features Nordberg WaterFlush crushers, a large thickener, and new patented vertical smooth flow (VSF) SX technology. The SX-EW plant will have an annual production capacity of 125 000 t. Geology of the deposit, open pit mining operations, crushing and classifying, heap leaching, the VSF solvent extraction technology and results from a pilot test unit, the 35m diameter Supaflo High Rate thickener, additional geological resource potential, and construction costs, are outlined. (J.M.McLaughlin)