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Discharge index tests on vertical drains
96A
922183 Determination of OCR in clays by piezocone tests using cavity expansion and critical state concepts Mayne, P W Soils Found V31. .V2. June 1991, P65-76 Cavity expansion theory describes both the point resistance and excess induced pore pressure during piezocone penetration of clay in terms of undrained shear strength and rigidity index. If modified Cam clay theory is used to represent undrained soil behaviour in terms of stress history, the two theories combined can give an approximate value of in situ OCR in terms of effective stress friction angle and normalized piezocone parameters. It is possible to separate piezocones which measure pore pressures at the tip and those which measure just behind the tip. General applications and range of use are discussed.
922184 Eiasto-viscoplastic consolidation of a diatomaceous mudstonc Maekawa, H; Miyakita, K; Sekiguchi, H Soils Found V31, N2, June 1991, P93-107 Isotropic consolidation tests and permeability tests were carfled out on a diatomaceous mudstone in a high pressure triaxial cell. The material can be considered as naturally cemented with a highly porous skeleton. Secondary compression is small before initial yielding but becomes pronounced when load exceeds pre-consolidation pressure. Log permeability correlates linearly with void ratio. A coupled stress-flow finite element analysis of consolidation using an elasto-viscoplastic constitutive model (Sekiguchi, 1977) describes observed behaviour well.
922185 Drying, cracking, and subsidence of a clay soil in a iysimeter Bronswijk, J J B Soil Sci V152, N2, Aug 1991, P92-99 An undisturbed heavy clay soil in a lysimeter was exposed to evaporation under controlled conditions over a period of 82 days. Changes in water content were monitored by tensiometers and weighing, shrinkage was determined from surface subsidence. Loss of water was 40% less than from a silty soil under similar conditions. Drying was restricted to the top 150mm, about two thirds of this to the top 75mm. Shrinkage contributions from crack volume and surface subsidence were evaluated. The various stages of the shrinkage process can be correlated to changes in soil moisture content.
922186 Detection of aquifers susceptibility to land subsidence Prokopovich, N P Proc 4th International Conference on Land Subsidence, Houston, 12-17 May 1991 P27-33. Publ I A H S Press: Wallingford, 1991 The application of consolidometer testing to determine the susceptibility of confined aquifer materials to compaction and to quantify the amount of subsidence possible on lowering of piezometric head is described. Undisturbed core samples of aquifer sediments are preconsolidated to a stress level equivalent to overburden pressure minus piezometric head. A second test is then carried out on the already compacted material without any correction for piezometric support. Results indicate susceptibility to subsidence and its potential magnitude. Extension to unconfined aquifers is possible.
922187 Discharge index tests on vertical drains Ooostveen. J P" Troost, G H Proc 4th International Conference on Geotextiles, Geomembranes and Relate'l Pro,_lucrv, The Hague, 28 May-I June 1990 I'1. P345-35, ?,,'-~! .: ::rdam: A ,4 Balkema, 1990 Vertical drainage with prcfabr!,::~'c~, units is widely used to speed consolidation. Water discharge capacity of these drains, their most important p::r:=;eter. (.~'pends on horizontal soil pressure which compres~c, the drain, drain condition which is affected by vertical soil movement with kinking at large settlements, rate of water flow, and long term discharge behaviour. Laboratory tests have been developed which allow discharge capacity to be measured t\w drains as installed and in a kinked state, simulating large settlements. The drain kinker can realistically reproduce buckling seen in the field.
922188 Long-term settlements over tunnels: an eleven-year study at Grimsby O'Reilly, M P: Mair, R J: Alderman, G H Proe Tunnelling '91, London, 14-18 April 1991 P55-64. Publ London: Elsevier, 1991 Ground movements over tunnels consist of short term settlements occurring immediately after construction and long term movements associated with consolidation of the disturbed ground. An 11 year study for the case of the Haycroft Relief Sewer, a 3m diameter tunnel in very soft clay soil, is presented. When equilibrium was reached, the width of the settlement trough had more than doubled the early-time value, and maximum displacements had increased by 46-48mm. Finite element modelling using the code ICFEP predicted ground movements well.
922189 Field monitoring of moisture conditions in expansive soils Pomper, P S; Lee, H C; Bratton, W L; Wray, W K Proc 1990 Annual Symposium on Geology and Geotechnical Engineering, Instrumentation and Computer Applications, Poeatello, 4-6 April 1990 P36.1-36.14. Publ Pocatello: Idaho State University. 1990 Surface elevation, soil moisture content, soil temperature, and soil suction were monitored over a 3 year period at 2 sites, one with a dry climate, the other with a wet climate. Performance of the instrumentation is described and observations are made of the soil structure interaction of slab-on-ground foundations. Centre lift appears to be the developing distortion pattern in the dry climate, and also in the wet climate if there is sufficient moisture present. Data can be used to estimate maximum shrink-heave magnitudes. The Thornthwaite Moisture Index reasonably predicts values of the edge moisture variation distance.
922190 Settlement of municipal refuse Edil, T B; Ranguette, V J; Wuellner, W W Proc Symposium on Geotechnics o f Waste Fills - Theory and Practice, Pittsburg, 10-13 Sept 1989 P225-239. Publ Philadelphia: ASTM, 1990 ( A S T M Special Technical Publication 1070) Refuse settlement in sanitary landfills is a complex process, dominated by secondary compression. If it can be predicted accurately, remaining life of existing landfills can be optimised, and better prediction of surface refuse movement and its effect on cover integrity and of future vertical expansion will be possible. Mechanical, ravelling, physicochemical change, and biological degradation components contribute to movement. The
© 1992 Pergamon Press Ltd. Reproduction not permitted
922183 Determination of OCR in clays by piezocone tests using cavity expansion and critical state concepts Mayne, P W Soils Found V31. .V2. June 1991, P65-76 Cavity expansion theory describes both the point resistance and excess induced pore pressure during piezocone penetration of clay in terms of undrained shear strength and rigidity index. If modified Cam clay theory is used to represent undrained soil behaviour in terms of stress history, the two theories combined can give an approximate value of in situ OCR in terms of effective stress friction angle and normalized piezocone parameters. It is possible to separate piezocones which measure pore pressures at the tip and those which measure just behind the tip. General applications and range of use are discussed.
922184 Eiasto-viscoplastic consolidation of a diatomaceous mudstonc Maekawa, H; Miyakita, K; Sekiguchi, H Soils Found V31, N2, June 1991, P93-107 Isotropic consolidation tests and permeability tests were carfled out on a diatomaceous mudstone in a high pressure triaxial cell. The material can be considered as naturally cemented with a highly porous skeleton. Secondary compression is small before initial yielding but becomes pronounced when load exceeds pre-consolidation pressure. Log permeability correlates linearly with void ratio. A coupled stress-flow finite element analysis of consolidation using an elasto-viscoplastic constitutive model (Sekiguchi, 1977) describes observed behaviour well.
922185 Drying, cracking, and subsidence of a clay soil in a iysimeter Bronswijk, J J B Soil Sci V152, N2, Aug 1991, P92-99 An undisturbed heavy clay soil in a lysimeter was exposed to evaporation under controlled conditions over a period of 82 days. Changes in water content were monitored by tensiometers and weighing, shrinkage was determined from surface subsidence. Loss of water was 40% less than from a silty soil under similar conditions. Drying was restricted to the top 150mm, about two thirds of this to the top 75mm. Shrinkage contributions from crack volume and surface subsidence were evaluated. The various stages of the shrinkage process can be correlated to changes in soil moisture content.
922186 Detection of aquifers susceptibility to land subsidence Prokopovich, N P Proc 4th International Conference on Land Subsidence, Houston, 12-17 May 1991 P27-33. Publ I A H S Press: Wallingford, 1991 The application of consolidometer testing to determine the susceptibility of confined aquifer materials to compaction and to quantify the amount of subsidence possible on lowering of piezometric head is described. Undisturbed core samples of aquifer sediments are preconsolidated to a stress level equivalent to overburden pressure minus piezometric head. A second test is then carried out on the already compacted material without any correction for piezometric support. Results indicate susceptibility to subsidence and its potential magnitude. Extension to unconfined aquifers is possible.
922187 Discharge index tests on vertical drains Ooostveen. J P" Troost, G H Proc 4th International Conference on Geotextiles, Geomembranes and Relate'l Pro,_lucrv, The Hague, 28 May-I June 1990 I'1. P345-35, ?,,'-~! .: ::rdam: A ,4 Balkema, 1990 Vertical drainage with prcfabr!,::~'c~, units is widely used to speed consolidation. Water discharge capacity of these drains, their most important p::r:=;eter. (.~'pends on horizontal soil pressure which compres~c, the drain, drain condition which is affected by vertical soil movement with kinking at large settlements, rate of water flow, and long term discharge behaviour. Laboratory tests have been developed which allow discharge capacity to be measured t\w drains as installed and in a kinked state, simulating large settlements. The drain kinker can realistically reproduce buckling seen in the field.
922188 Long-term settlements over tunnels: an eleven-year study at Grimsby O'Reilly, M P: Mair, R J: Alderman, G H Proe Tunnelling '91, London, 14-18 April 1991 P55-64. Publ London: Elsevier, 1991 Ground movements over tunnels consist of short term settlements occurring immediately after construction and long term movements associated with consolidation of the disturbed ground. An 11 year study for the case of the Haycroft Relief Sewer, a 3m diameter tunnel in very soft clay soil, is presented. When equilibrium was reached, the width of the settlement trough had more than doubled the early-time value, and maximum displacements had increased by 46-48mm. Finite element modelling using the code ICFEP predicted ground movements well.
922189 Field monitoring of moisture conditions in expansive soils Pomper, P S; Lee, H C; Bratton, W L; Wray, W K Proc 1990 Annual Symposium on Geology and Geotechnical Engineering, Instrumentation and Computer Applications, Poeatello, 4-6 April 1990 P36.1-36.14. Publ Pocatello: Idaho State University. 1990 Surface elevation, soil moisture content, soil temperature, and soil suction were monitored over a 3 year period at 2 sites, one with a dry climate, the other with a wet climate. Performance of the instrumentation is described and observations are made of the soil structure interaction of slab-on-ground foundations. Centre lift appears to be the developing distortion pattern in the dry climate, and also in the wet climate if there is sufficient moisture present. Data can be used to estimate maximum shrink-heave magnitudes. The Thornthwaite Moisture Index reasonably predicts values of the edge moisture variation distance.
922190 Settlement of municipal refuse Edil, T B; Ranguette, V J; Wuellner, W W Proc Symposium on Geotechnics o f Waste Fills - Theory and Practice, Pittsburg, 10-13 Sept 1989 P225-239. Publ Philadelphia: ASTM, 1990 ( A S T M Special Technical Publication 1070) Refuse settlement in sanitary landfills is a complex process, dominated by secondary compression. If it can be predicted accurately, remaining life of existing landfills can be optimised, and better prediction of surface refuse movement and its effect on cover integrity and of future vertical expansion will be possible. Mechanical, ravelling, physicochemical change, and biological degradation components contribute to movement. The
© 1992 Pergamon Press Ltd. Reproduction not permitted