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Potential contaminant movement through soil joints. Technical note
I IOA region 35 to 130m below ground surface, sinkholes are anomalously large, and a piping rather than collapse formation mechanism is likely. These observations are explained in terms of hydrological and geological setting.
893023 Influence of impermeable beds on the collapse of bedrock voids in the vadose zone Mylroie, J E Proc 2nd Multidisciplinary Conference on Sinkholes and the Environmental Impacts of Karst, Orlando, 9-11 February 1987 P95-99. Publ Rotterdam: A A Balkema, 1987 Impermeable beds in, on or under limestone strata can promote collapse of solution voids by controlling water flow in the zone above the water table. Focused water flow from breaks in an impermeable bed can develop vertical shafts which can enlarge and collapse or induce collapse in other cavities. Impermeable beds can also cause meandering or undercutting of conduits or backflooding of the zone immediately above water table. Knowledge of geological strata can give some indication of potentially troublesome areas.
893024 Fracture permeability: implications on cave and sinkhole development and their environmental assessments Veni, G Proc 2nd MuMdisciplinary Conference on Sinkholes and the Environmental Impacts of Karst, Orlando, 9-11 February 1987 PIOI-I05. Publ Rotterdam: A A Balkema. 1987 The four stages of sinkhole formation are illustrated: initiation, piracy when the conduit becomes the dominant hydrologic feature, integration with linkage to surface and subsurface features, and enlargement. The influence of permeability of the fractures in a rock mass on speed of groundwater transport, and how this affects the size, shape and distribution of the sinkholes formed is examined. Importance to land use and environmental sensitivity are discussed.
893025 Hydrologic effects from intense ground-water pumpage in East-Central Hillsborough County, Florida Bengtsson, T 0 Proc 2nd Multidisciplinary Conference on Sinkholes and the Environmental Impacts of Karst, Orlando, 9-11 February 1987 P109-114. Publ Rotterdam: A A Balkema, 1987 Groundwater pumping during winter for spraying to prevent frost damage or plant setting may have significant impact on the phreatic level of the Floridan aquifer. Observed effects, sinkhole formation, flood runoff damage, and pump failure, are described, and simulation by finite difference modelling illustrated. Remedial measures include surface water engineering and improved well design. Management recommendations to minimise the potentially serious problem of sinkhole formation are discussed.
Properties of Rocks and Soils Composition, structure texture and density 893026 Potential contaminant movement through soil joints. Technical note Kirkaldie, L Bull Assoc Engng GeM V25. N4, Not' 1988, P520-524 Soil joints in loess and lacustrine materials are described. The joints are always vertical, parallel and approximately equally spaced. Their age is unknown, but most are Pleistocene. The joints seem to have been propagated upwards suggesting a tectonic relation, although joints in lacustrine and alluvial deposits have been attributed to desiccation and stress release. Permeability is many times that of the surrounding soil, often acting as an open channel for water and contaminant movement through the unsaturated zone. 893027 Variations of porosity and permeability along a geothermal borehole. Relation with the clays content (In French) Baudracco, J; Cadot, J C lnt Assoc Engng GeM Bull N38, Oct 1988, P27-35 Petrophysical characteristics (porosity, gas and water permeability) and the salt and clay content of samples from a geothermal borehole have been studied. The gas permeability, porosity and mean size of the pores strongly decrease with increasing clay content. For a given sample, the water permeability has been continuously measured as a function of time. After an initial rapid drop, the permeability decreases more slowly and almost linearly as a function of time. The initial decrease is related to the motion of unconsolidated solid particles and the physisorption of water on clays. The further linear decrease is attributed to slow precipitation of silica gel. Auth. 893028 Geotechnical characteristics of soils susceptible to severe gullying in Eastern Nigeria Okagbue, C O; Ezechi, J I int Assoc Engng GeM Bull N38, Oct 1988, PIII-II9 Bag and tube soil samples were collected from 6 sites which are prone to gullying. The bag samples were used to determine grain size distribution, Atterberg limits and moisture-density relationships, and the tube samples to determine bulk density, water content, void ratio and porosity. Compacted samples were used to determine strength. Results show that predominantly sandy soils with low density and high permeability are most prone to severe gullying, and gullying is accelerated where permeability increases with depth in soils with low density and cohesion. 893029 Rock mass characterization using photoanalysis Franklin, J A; Maertz, N H; Bennett, C P lnt J Min GeM Engng V6, N2, July 1988, P97-112 The technique of photoanalysis for use in joint system characterisation is introduced. Some aspects of digital photoanalysis are outlined: (1) input, including face enhancement, photography and edge detection; (2) data processing, including correction for facetting effect, derivation of joint spacing and block size parameters and measurement of joint
cL 1989 Pergamon Press plc. Reproduction not permitted
893023 Influence of impermeable beds on the collapse of bedrock voids in the vadose zone Mylroie, J E Proc 2nd Multidisciplinary Conference on Sinkholes and the Environmental Impacts of Karst, Orlando, 9-11 February 1987 P95-99. Publ Rotterdam: A A Balkema, 1987 Impermeable beds in, on or under limestone strata can promote collapse of solution voids by controlling water flow in the zone above the water table. Focused water flow from breaks in an impermeable bed can develop vertical shafts which can enlarge and collapse or induce collapse in other cavities. Impermeable beds can also cause meandering or undercutting of conduits or backflooding of the zone immediately above water table. Knowledge of geological strata can give some indication of potentially troublesome areas.
893024 Fracture permeability: implications on cave and sinkhole development and their environmental assessments Veni, G Proc 2nd MuMdisciplinary Conference on Sinkholes and the Environmental Impacts of Karst, Orlando, 9-11 February 1987 PIOI-I05. Publ Rotterdam: A A Balkema. 1987 The four stages of sinkhole formation are illustrated: initiation, piracy when the conduit becomes the dominant hydrologic feature, integration with linkage to surface and subsurface features, and enlargement. The influence of permeability of the fractures in a rock mass on speed of groundwater transport, and how this affects the size, shape and distribution of the sinkholes formed is examined. Importance to land use and environmental sensitivity are discussed.
893025 Hydrologic effects from intense ground-water pumpage in East-Central Hillsborough County, Florida Bengtsson, T 0 Proc 2nd Multidisciplinary Conference on Sinkholes and the Environmental Impacts of Karst, Orlando, 9-11 February 1987 P109-114. Publ Rotterdam: A A Balkema, 1987 Groundwater pumping during winter for spraying to prevent frost damage or plant setting may have significant impact on the phreatic level of the Floridan aquifer. Observed effects, sinkhole formation, flood runoff damage, and pump failure, are described, and simulation by finite difference modelling illustrated. Remedial measures include surface water engineering and improved well design. Management recommendations to minimise the potentially serious problem of sinkhole formation are discussed.
Properties of Rocks and Soils Composition, structure texture and density 893026 Potential contaminant movement through soil joints. Technical note Kirkaldie, L Bull Assoc Engng GeM V25. N4, Not' 1988, P520-524 Soil joints in loess and lacustrine materials are described. The joints are always vertical, parallel and approximately equally spaced. Their age is unknown, but most are Pleistocene. The joints seem to have been propagated upwards suggesting a tectonic relation, although joints in lacustrine and alluvial deposits have been attributed to desiccation and stress release. Permeability is many times that of the surrounding soil, often acting as an open channel for water and contaminant movement through the unsaturated zone. 893027 Variations of porosity and permeability along a geothermal borehole. Relation with the clays content (In French) Baudracco, J; Cadot, J C lnt Assoc Engng GeM Bull N38, Oct 1988, P27-35 Petrophysical characteristics (porosity, gas and water permeability) and the salt and clay content of samples from a geothermal borehole have been studied. The gas permeability, porosity and mean size of the pores strongly decrease with increasing clay content. For a given sample, the water permeability has been continuously measured as a function of time. After an initial rapid drop, the permeability decreases more slowly and almost linearly as a function of time. The initial decrease is related to the motion of unconsolidated solid particles and the physisorption of water on clays. The further linear decrease is attributed to slow precipitation of silica gel. Auth. 893028 Geotechnical characteristics of soils susceptible to severe gullying in Eastern Nigeria Okagbue, C O; Ezechi, J I int Assoc Engng GeM Bull N38, Oct 1988, PIII-II9 Bag and tube soil samples were collected from 6 sites which are prone to gullying. The bag samples were used to determine grain size distribution, Atterberg limits and moisture-density relationships, and the tube samples to determine bulk density, water content, void ratio and porosity. Compacted samples were used to determine strength. Results show that predominantly sandy soils with low density and high permeability are most prone to severe gullying, and gullying is accelerated where permeability increases with depth in soils with low density and cohesion. 893029 Rock mass characterization using photoanalysis Franklin, J A; Maertz, N H; Bennett, C P lnt J Min GeM Engng V6, N2, July 1988, P97-112 The technique of photoanalysis for use in joint system characterisation is introduced. Some aspects of digital photoanalysis are outlined: (1) input, including face enhancement, photography and edge detection; (2) data processing, including correction for facetting effect, derivation of joint spacing and block size parameters and measurement of joint
cL 1989 Pergamon Press plc. Reproduction not permitted