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Multilevel slug tests with comparisons to tracer data
221A
See also: 924030, 924470
behaviour due to the concentration of flow in the dominant joints. Even in the short term experiments, decrease in permeability due to dissolution/precipitation reactions was observed. Implications to H D R projects are discussed.
924124 Large-scale laboratory permeability testing of a compacted clay soil Shackelford, C D; Javed, F Geotecl~ Test J VI4, N2, June 1991, P171-179
924128 Access to stochastic fractured media characteristics by harmonic hydraulic pumping. Technical note Jouanna, P Int J Rock Mecli Min Sci V29, NI, Jan 1992, P83-87
Constant head permeability tests were carried out on specimens of a compacted naturally occurring silty clay soil in double-ring, rigid wall permeameters. Specimen size was 0.914 by 0.914 by 0.457m. Similar small scale tests were carried out on samples compacted in a standard Proctor mould. Results show that for a given soil fraction the permeability was always higher (0.6-2.4 order of magnitude) when measured on the large scale specimen. Reasons for this size effect are discussed. The effect is most significant where a significant portion of the soil sample has clod size large in relation to permeameter dimensions.
Hydraulic harmonic pumping involves creating a sinusoidal flow in a section between two packers in an investigation well and measuring the resulting sinusoidal head or pressure in the injection chamber. An analysis is presented which investigates stochastic distribution of voids or fissures in a rock mass using results of such tests. It is illustrated starting from the deterministic case of a large number of sub-horizontal fractures.
Permeability and capillarity
924125 Multilevel slug tests with comparisons to tracer data Melville, J G; Molz, F Z; Guven, O; Widdowson, M A Ground Water V29, N6, Nov-Dec 1991, P897-907 Multilevel slug tests and tracer injection and travel experiments were carried out at the same location in a confined granular aquifer. Slug test data were interpreted using a radial flow model and a finite element model including both radial and vertical flow. Hydraulic conductivities inferred from the first model were about 50% greater than those from the second. Nondimensional hydraulic conductivity profiles from the slug tests and tracer experiments were similar, supporting the use of multilevel slug tests to characterise hydraulic conductivity profiles in the aquifer.
924126 Field scale investigation of infiltration into a compacted soil finer Panno, S V; Herzog, B L; Cartwright, K; Rehfeldt, K R; Krapac, I G; Hensel, B R Ground Water V29, N6, Nov-Dec 1991, P914-921 A compacted liner of illitic grey loam, 8m by 15m by 0.9m, similar to that used in waste disposal sites, was flooded and has been studied over a 2 year period. Four large ring (LR) and 32 small ring (SR) infiltrometers and a water balance (WB) method accounting for total infiltration and evaporation have been used to monitor infiltration. Fluxes have been analysed. WB and SR data are similar, but there is evidence of leakage in the LRs. Geostatistical analysis of SR data suggests that it is possible to construct a liner with uniformly low saturated hydraulic conductivity. Average values calculated from SR data indicate breakthrough some 6 years after initial ponding.
924127 Thermal cracking induced by water flow through joints in heated granite. Technical note Zhao, J; Brown, E T lnt J Rock Mech Min Sci V29, NI, Jan 1992, P77-82 The flow properties of cylindrical samples of Carnmenellis granite containing through-going natural or artificial fractures have been examined at room temperature and temperatures up to 200 deg C. Fresh and tested samples were examined in the SEM. Observations indicate cracks and pores initiated or extended by hydrothermal action may provide additional flow paths. These, however, have little effect on overall hydraulic
924129 Pollutant migration through liner underlain by fractured soil Rowe, R K; Booker, J R J Geotech Engng Div ASCE I,'117, NI2, Dec 1991, P19021919 A simple semianalytic model is presented to describe migration of contaminant through an unfractured clayey liner underlain by fractured soil and rock into an aquifer. The model can include advoetive-diffusive-dispersive transport through the liner, advective-dispersive transport in the fractures, matrix diffusion from the fractures into the soil, sorption on the fracture surface and in the soil matrix, a finite mass of contaminant in the landfill, and dilution in the aquifer. A hypothetical case of a fill over fractured glacial till with no liner and with a liner of reworked till is considered. Results are compared to those of analyses considering the liner alone or the full thickness to be fractured.
924130 Laboratory determination of unsaturated hydraulic conductivity using a generalized-form hydraulic model Valiantzas, J D; Sassalou, A J Hydrol V128, NI-4, Nov 1991, P293-304 Conventional pore structure models which predict the hydraulic conductivity/water content function from water retention data often give results which differ from observed values. An alternative approach is presented in which a statistical model in a more general form with an additional unknown parameter is used, in conjunction with the one-step outflow laboratory method. Earlier results were reformulated on the basis of the Brooks and Corey model to obtain cumulative outflow data. The method is illustrated applied to a sand and a silt loam soil.
924131 Effects of overburden stress on the specific storage and hydraulic conductivity of artesian aquifers Sepulveda, N; Zack, A L J Hydeoi V128. NI-4, Nov 1991, P305-321 Depth dependence of specific storage and hydraulic conductivity as a result of overburden stress on horizontally isotropic artesian aquifers has been studied. Vertical variations in void ratio of the aquifer as a result of overburden stress determine pore volume compressibility and matrix permeability at specific depths and these in turn influence specific storage and hydraulic conductivity. Time-drawdown curves are evaluated for two sands under different overburden stresses. Shallow artesian aquifers with high matrix compressibility and under low overburden stress will not behave according to the classical Theis equation. Deep artesian aquifers will show negligible deviation.
© 1992 Pergamon Press Ltd. Reproduction not permitted
See also: 924030, 924470
behaviour due to the concentration of flow in the dominant joints. Even in the short term experiments, decrease in permeability due to dissolution/precipitation reactions was observed. Implications to H D R projects are discussed.
924124 Large-scale laboratory permeability testing of a compacted clay soil Shackelford, C D; Javed, F Geotecl~ Test J VI4, N2, June 1991, P171-179
924128 Access to stochastic fractured media characteristics by harmonic hydraulic pumping. Technical note Jouanna, P Int J Rock Mecli Min Sci V29, NI, Jan 1992, P83-87
Constant head permeability tests were carried out on specimens of a compacted naturally occurring silty clay soil in double-ring, rigid wall permeameters. Specimen size was 0.914 by 0.914 by 0.457m. Similar small scale tests were carried out on samples compacted in a standard Proctor mould. Results show that for a given soil fraction the permeability was always higher (0.6-2.4 order of magnitude) when measured on the large scale specimen. Reasons for this size effect are discussed. The effect is most significant where a significant portion of the soil sample has clod size large in relation to permeameter dimensions.
Hydraulic harmonic pumping involves creating a sinusoidal flow in a section between two packers in an investigation well and measuring the resulting sinusoidal head or pressure in the injection chamber. An analysis is presented which investigates stochastic distribution of voids or fissures in a rock mass using results of such tests. It is illustrated starting from the deterministic case of a large number of sub-horizontal fractures.
Permeability and capillarity
924125 Multilevel slug tests with comparisons to tracer data Melville, J G; Molz, F Z; Guven, O; Widdowson, M A Ground Water V29, N6, Nov-Dec 1991, P897-907 Multilevel slug tests and tracer injection and travel experiments were carried out at the same location in a confined granular aquifer. Slug test data were interpreted using a radial flow model and a finite element model including both radial and vertical flow. Hydraulic conductivities inferred from the first model were about 50% greater than those from the second. Nondimensional hydraulic conductivity profiles from the slug tests and tracer experiments were similar, supporting the use of multilevel slug tests to characterise hydraulic conductivity profiles in the aquifer.
924126 Field scale investigation of infiltration into a compacted soil finer Panno, S V; Herzog, B L; Cartwright, K; Rehfeldt, K R; Krapac, I G; Hensel, B R Ground Water V29, N6, Nov-Dec 1991, P914-921 A compacted liner of illitic grey loam, 8m by 15m by 0.9m, similar to that used in waste disposal sites, was flooded and has been studied over a 2 year period. Four large ring (LR) and 32 small ring (SR) infiltrometers and a water balance (WB) method accounting for total infiltration and evaporation have been used to monitor infiltration. Fluxes have been analysed. WB and SR data are similar, but there is evidence of leakage in the LRs. Geostatistical analysis of SR data suggests that it is possible to construct a liner with uniformly low saturated hydraulic conductivity. Average values calculated from SR data indicate breakthrough some 6 years after initial ponding.
924127 Thermal cracking induced by water flow through joints in heated granite. Technical note Zhao, J; Brown, E T lnt J Rock Mech Min Sci V29, NI, Jan 1992, P77-82 The flow properties of cylindrical samples of Carnmenellis granite containing through-going natural or artificial fractures have been examined at room temperature and temperatures up to 200 deg C. Fresh and tested samples were examined in the SEM. Observations indicate cracks and pores initiated or extended by hydrothermal action may provide additional flow paths. These, however, have little effect on overall hydraulic
924129 Pollutant migration through liner underlain by fractured soil Rowe, R K; Booker, J R J Geotech Engng Div ASCE I,'117, NI2, Dec 1991, P19021919 A simple semianalytic model is presented to describe migration of contaminant through an unfractured clayey liner underlain by fractured soil and rock into an aquifer. The model can include advoetive-diffusive-dispersive transport through the liner, advective-dispersive transport in the fractures, matrix diffusion from the fractures into the soil, sorption on the fracture surface and in the soil matrix, a finite mass of contaminant in the landfill, and dilution in the aquifer. A hypothetical case of a fill over fractured glacial till with no liner and with a liner of reworked till is considered. Results are compared to those of analyses considering the liner alone or the full thickness to be fractured.
924130 Laboratory determination of unsaturated hydraulic conductivity using a generalized-form hydraulic model Valiantzas, J D; Sassalou, A J Hydrol V128, NI-4, Nov 1991, P293-304 Conventional pore structure models which predict the hydraulic conductivity/water content function from water retention data often give results which differ from observed values. An alternative approach is presented in which a statistical model in a more general form with an additional unknown parameter is used, in conjunction with the one-step outflow laboratory method. Earlier results were reformulated on the basis of the Brooks and Corey model to obtain cumulative outflow data. The method is illustrated applied to a sand and a silt loam soil.
924131 Effects of overburden stress on the specific storage and hydraulic conductivity of artesian aquifers Sepulveda, N; Zack, A L J Hydeoi V128. NI-4, Nov 1991, P305-321 Depth dependence of specific storage and hydraulic conductivity as a result of overburden stress on horizontally isotropic artesian aquifers has been studied. Vertical variations in void ratio of the aquifer as a result of overburden stress determine pore volume compressibility and matrix permeability at specific depths and these in turn influence specific storage and hydraulic conductivity. Time-drawdown curves are evaluated for two sands under different overburden stresses. Shallow artesian aquifers with high matrix compressibility and under low overburden stress will not behave according to the classical Theis equation. Deep artesian aquifers will show negligible deviation.
© 1992 Pergamon Press Ltd. Reproduction not permitted