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Compaction of opencast backfill
212A
Compressibility, swelling and consolidation See also. 904369 904121 Graphical method for determining the coefficient of consolidation CV from a flow-pump permeability test. Technical note Morin, R H; Olsen, H W; Nelson, K R; Gill, J D Geoteeh Test J VI2, N4, Dec 1989, P302-307 In the flow pump test, fluid is infused into or withdrawn from specimens at a constant rate. Permeability is derived using Darcy's law once hydraulic head differences induced have reached a steady state. The characteristic pressure response during transient phases of the test has been examined theoretically, and it is possible to determine accurate values of coefficient of consolidation and coefficient of volume change. A slight manipulation of the analytical solution is presented, which allows simple graphical evaluation of these parameters. 904122 Analysis of compressibility of sensitive soils Nagaraj, T S; Murthy, B R S; Vatsala, A; Joshi, R C J Geotech Engng Div ASCE VII6. NI. Jan 1990. P105-118 it is almost impossible to obtain truly undisturbed samples of sensitive soils, and predictions of settlement based on laboratory test results may be erroneous. Schmertmann (1953) suggested modification of laboratory test results from partially disturbed specimens could be used in prediction of field void ratio-consolidation pressure relations. A critical review of this approach is presented. A simple method is suggested for determining most probable field yield stress and generating the field void ratio-consolidation pressure curve from modified laboratory oedometer data or field vane data. 904123 Physical model study of differential settlement on reclaimed land Sweigard, R J; Rohatgi, M Min Engng V42. N2. Feb 1990. P191-194 Differential settlement causing depressions can lead to drainage problems on reclaimed land used for agriculture. Laboratory model simulations of settlement of a reconstructed soil layer over rock spoil were used to examine influence on differential movement of parameters including relative amount of rock and unconsolidated overburden in the undisturbed condition. size of rock fragments, and soil porosity and density. Results suggest magnitude of settlement is primarily influenced by the behaviour of the unconsolidated soil layer of the initial overburden. 904124 Compaction of opencast backfill Thompson, J Quarry ~lanage Jan 1990. Pl l-16 Restoration of opencast sites often requires compaction in full or in part of the extraction area. Technical specifications for the compaction are based on MoT guidelines, modified to reflect anticipated site development and materials to be excavated. Compaction trials, target and permissable density and water content, settlement monitoring, and geotechnical certification of the site are discussed. Effects of compaction operations on the working of the opencast site are also considered.
904125 Mine tailings, dispersants and fiocculants Fell. R Proc Conference on Hydraulic Fill Structures, Fort Collins. 15-18 April 1988 P711-730. Publ New York." ASCE. 1988 ( Geotechnical Special Publication No 21) A laboratory study was carried out to assess the effect on settled density of adding dispersants and flocculants to high clay content tailings from ore treatment plants. The mechanism of operation of flocculants and dispersants is outlined. Column settling tests were performed to determine the rate of settlement of tailings mixed with flocculant or dispersant. Results show that settled density of the railings is not improved by addition of flocculants, but that settled density of some tailings is improved by addition of small amounts of dispersants prior to deposition. 904126 Properties of sedimented double alkali FGD slurries Krizek, R J; Tatioussian, S W; Atmatzidis, D K Proc Conference on Hydraulic Fill Structures, Fort Collins, 15-18 April 1988 P778-794. Publ New York: ASCE. 1988 (Geotechnical Special Publication No 21) A study was undertaken to assess the possibility of codisposing double alkali F G D sludge and fly ash, with or without stability additives, in a settling pond, and then reclaiming the disposal site for further use. Sedimentation tests were carried out on laboratory prepared slurries, and permeability, strength, moisture content and dry density measured to evaluate the effects of variations in ash-to-FGD ratio, solids concentration, amount and type of additive and curing time. Results and engineering implications are discussed. 904127 Effects of long-term Ko-consolidation on undrained strength of clay Yasuhara, K; Hirao, K; Ue, S Proc International Conference on Rheology and Soil Mechanics, Coventry, 12-16 Sept 1988 P273-287. Publ London." Elset'ier, 1988 The effect of secondary compression on the undrained strength of clay has been studied. Long-term undrained consolidation tests were carried out on highly plastic clay to measure Ko during secondary compression, and results, which showed variation in Ko influences undrained strength, were analysed on a total stress basis. A method for predicting the variations of Ko with time during secondary compression was developed, along with a method for estimating the change in undrained strength due to secondary compression. 904128 Engineering behaviour of residual soils Pannila, I; Thuralrajah, A Proc International Conference on Engineering Problems of Regional Soils, Beijing, 11-15 August 1988 P680-685. Publ Beijing: International Academic Publishers, 1989 Results of classification tests and one dimensional consolidation tests on residual soils from Sri Lanka are presented. Soil pretreatment (drying) before classification alters clay fraction and hence plasticity. Consolidation settlement consisted of immediate, primary consolidation, and secondary consolidation components. Ratio of immediate to total settlement increased with increase in pressure increment ratio, whilst the secondary settlement contribution decreased. At long times, a logarithmic time-settlement relation is observed.
"C 1990 Pergamon Press plc. Reproduction not permitted
Compressibility, swelling and consolidation See also. 904369 904121 Graphical method for determining the coefficient of consolidation CV from a flow-pump permeability test. Technical note Morin, R H; Olsen, H W; Nelson, K R; Gill, J D Geoteeh Test J VI2, N4, Dec 1989, P302-307 In the flow pump test, fluid is infused into or withdrawn from specimens at a constant rate. Permeability is derived using Darcy's law once hydraulic head differences induced have reached a steady state. The characteristic pressure response during transient phases of the test has been examined theoretically, and it is possible to determine accurate values of coefficient of consolidation and coefficient of volume change. A slight manipulation of the analytical solution is presented, which allows simple graphical evaluation of these parameters. 904122 Analysis of compressibility of sensitive soils Nagaraj, T S; Murthy, B R S; Vatsala, A; Joshi, R C J Geotech Engng Div ASCE VII6. NI. Jan 1990. P105-118 it is almost impossible to obtain truly undisturbed samples of sensitive soils, and predictions of settlement based on laboratory test results may be erroneous. Schmertmann (1953) suggested modification of laboratory test results from partially disturbed specimens could be used in prediction of field void ratio-consolidation pressure relations. A critical review of this approach is presented. A simple method is suggested for determining most probable field yield stress and generating the field void ratio-consolidation pressure curve from modified laboratory oedometer data or field vane data. 904123 Physical model study of differential settlement on reclaimed land Sweigard, R J; Rohatgi, M Min Engng V42. N2. Feb 1990. P191-194 Differential settlement causing depressions can lead to drainage problems on reclaimed land used for agriculture. Laboratory model simulations of settlement of a reconstructed soil layer over rock spoil were used to examine influence on differential movement of parameters including relative amount of rock and unconsolidated overburden in the undisturbed condition. size of rock fragments, and soil porosity and density. Results suggest magnitude of settlement is primarily influenced by the behaviour of the unconsolidated soil layer of the initial overburden. 904124 Compaction of opencast backfill Thompson, J Quarry ~lanage Jan 1990. Pl l-16 Restoration of opencast sites often requires compaction in full or in part of the extraction area. Technical specifications for the compaction are based on MoT guidelines, modified to reflect anticipated site development and materials to be excavated. Compaction trials, target and permissable density and water content, settlement monitoring, and geotechnical certification of the site are discussed. Effects of compaction operations on the working of the opencast site are also considered.
904125 Mine tailings, dispersants and fiocculants Fell. R Proc Conference on Hydraulic Fill Structures, Fort Collins. 15-18 April 1988 P711-730. Publ New York." ASCE. 1988 ( Geotechnical Special Publication No 21) A laboratory study was carried out to assess the effect on settled density of adding dispersants and flocculants to high clay content tailings from ore treatment plants. The mechanism of operation of flocculants and dispersants is outlined. Column settling tests were performed to determine the rate of settlement of tailings mixed with flocculant or dispersant. Results show that settled density of the railings is not improved by addition of flocculants, but that settled density of some tailings is improved by addition of small amounts of dispersants prior to deposition. 904126 Properties of sedimented double alkali FGD slurries Krizek, R J; Tatioussian, S W; Atmatzidis, D K Proc Conference on Hydraulic Fill Structures, Fort Collins, 15-18 April 1988 P778-794. Publ New York: ASCE. 1988 (Geotechnical Special Publication No 21) A study was undertaken to assess the possibility of codisposing double alkali F G D sludge and fly ash, with or without stability additives, in a settling pond, and then reclaiming the disposal site for further use. Sedimentation tests were carried out on laboratory prepared slurries, and permeability, strength, moisture content and dry density measured to evaluate the effects of variations in ash-to-FGD ratio, solids concentration, amount and type of additive and curing time. Results and engineering implications are discussed. 904127 Effects of long-term Ko-consolidation on undrained strength of clay Yasuhara, K; Hirao, K; Ue, S Proc International Conference on Rheology and Soil Mechanics, Coventry, 12-16 Sept 1988 P273-287. Publ London." Elset'ier, 1988 The effect of secondary compression on the undrained strength of clay has been studied. Long-term undrained consolidation tests were carried out on highly plastic clay to measure Ko during secondary compression, and results, which showed variation in Ko influences undrained strength, were analysed on a total stress basis. A method for predicting the variations of Ko with time during secondary compression was developed, along with a method for estimating the change in undrained strength due to secondary compression. 904128 Engineering behaviour of residual soils Pannila, I; Thuralrajah, A Proc International Conference on Engineering Problems of Regional Soils, Beijing, 11-15 August 1988 P680-685. Publ Beijing: International Academic Publishers, 1989 Results of classification tests and one dimensional consolidation tests on residual soils from Sri Lanka are presented. Soil pretreatment (drying) before classification alters clay fraction and hence plasticity. Consolidation settlement consisted of immediate, primary consolidation, and secondary consolidation components. Ratio of immediate to total settlement increased with increase in pressure increment ratio, whilst the secondary settlement contribution decreased. At long times, a logarithmic time-settlement relation is observed.
"C 1990 Pergamon Press plc. Reproduction not permitted