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Long-term consolidation characteristic of diluvial clay in Osaka Bay
295A 925171 Drainage efficiency of sand layer in layered clay-sand reclamation Tan, S A; Liang, K M; Yong, K Y; Lee, S L d Geoteck Engng Div ASCE 1/118, N2, Feb 1992, P209-228 In the layered clay-sand scheme for land reclamation, pioneered in Singapore to conserve sand resources, rate of consolidation will depend on drainage efficiency of sand layers. The governing equations for the problem are formulated, and a characteristic controlling factor is obtained, comprising of permeability and flow-length ratios of the sand and clay, together with the ratio of sand layer thickness to its length. If drainage efficiency is defined on the basis of its retardation to primary consolidation settlement, a unique efficiency value can be obtained as a function of the characteristic factor for 50% and 90% degree of settlement. The value of the factor of above 20 gives drainage efficiency above 90%; a value of 6 gives adequate drainage efficiency of 80%. 925172 Long-term consolidation characteristic of diluvial clay in Osaka Bay Akai, K; Kamon, M; Sano, I; Soga, K Soils Found V31, N4, Dec 1991, P61-74 Consolidation of materials at depth must be considered in large-scale reclamation projects. The Osaka Bay diluvial clay is in a quasi-overeonsolidated state due to cementation bonding. Compression index and void ratio are large, despite great overburden pressures. Long term consolidation tests indicate that the coefficient of secondary compression of this material tends to that of the normally consolidated region at large times. Clay behaving as overconsolidated in tests may behave as normally consolidated on site, and in situ secondary compression based on laboratory results may be an underestimate. Using the information gained, it is possible to accurately predict settlement for two Osaka Bay reclamation works. 925173 Effect of aging marine clay and its duplication by high temperature consolidation Tsuchida, T; Kobayashi, M; Mizukami, J Soils Found V31, N4, Dec 1991, P133-147
settlements are correctly predicted. A small error in predicted rate of settlement results from ignoring changes in radial properties. 925175 Deformation of coastal silty soils Cuellar, V; Oteo, C; Olalla, C; Monte, J L Proc lOth European Conference on Soil Mechanics and Foundation Engineering, Florence, 26.30 May 1991 VI, P5760. Publ Rotterdam: A A Balkema, 1991 Tests were carried out to characterise the compressibility and consolidation behaviour of soft silty sands and underlying normally consolidated stratified clays around Huelva harbour, Spain. Pore pressure dissipation tests were carried out using a piezocone penetrometer and permeability and consolidation parameters compared to those from a self boring penetrometer and laboratory one-dimensional consolidation tests on undisturbed samples. Results are consistent with reported data from trial embankments in the same soil formation. 925176 End-of-primary consolidation of peat Edil, T C; Fox, P J; Lan, L T Proc lOth European Conference on Soil Mechanics and Foundation Engineering, Florence, 26-30 May 1991 V1, P6568. Publ Rotterdam: A A Balkema, 1991 A series of end-of-primary (EOP) and long term oedometer tests was carried out on thick and thin specimens of a fibrous peat with the same aspect ratio. The applicability of the EOP concept for peats is examined on the basis of the test results. Conventional curve fitting techniques for organic soils were unreliable for the peat. No significant difference was found between EOP compression curves from long duration and EOP tests. EOP tests on samples of different thickness indicated a tendency to deviate from the unique EOP concept in the virgin loading stage. The use of thin specimens to evaluate EOP void ratio may be questionable. 925177 Relationship between the mineralogical data and the swelling of the marlstone of the Asco Power Plant foundation Esteban, F; Sagaseta, C; Soriano, A Proc lOth European Conference on Soil Mechanics and Foundation Engineering, Florence, 26-30 May 1991 V1, P6972. Publ Rotterdam: A d Balkema, 1991
The effects of ageing on the mechanical properties of marine clays was studied by comparing behaviour of undisturbed and remoulded samples. Compression index and secondary compression index of natural aged clays show peak values when consolidation pressure is slightly higher than consolidation yield stress. A compression index ratio is defined as a representation of ageing effects for natural clays. Values of this parameter for Japanese alluvial clays and aged Canadian clays are compared. Consolidation of clay slurries at 75 deg C followed by cooling produces samples similar mechanically to lightly aged clays. Accelerated cementation is the probable cause of this effect.
Free swell tests were carried out on unaltered and remoulded samples of the Tertiary gypsum-marl evaporitic rocks from beneath the foundations of the Asco II nuclear plant in Spain. Relations between mineralogical composition and swelling behaviour have been examined. The importance of the presence of sulphates, in particular anhydrite, to longer term swelling is described.
925174 Sand drain induced subsidence of a peat McNulty, E G Proc 4th International Conference on Land Subsidence, Houston, 12-17 May 1991 P333-340. Publ IAHS Press: Wallingford, 1991
925178 Pore pressure dissipation of highly fissured clays Federico, F; Musso, A Proc lOth European Conference on Soil Mechanics and Foundation Engineering, Florence, 26-30 May 1991 VI, P7782. Publ Rotterdam: A A Balkema, 1991
It has been claimed that sand drains do not accelerate the consolidation of peat because of the predominance of creep effects, and in addition the increase in effective stress causes decrease in radial hydraulic conductivity, which will in fact retard settlement. Predictions from nonlinear, large scale finite element analysis are compared to field data. If field disturbance due to construction activity is taken into account, field
One dimensional consolidation of an intensely fissured clay has been studied, with fluid exchange between fissures and matrix pores taken into account. Because of the role of the fissures in the dual porosity medium, the layer thickness does not have the same important effect as in classical Terzaghi theory. The extrapolation of small sample laboratory results to field scale is questionable. An analogue model with elastic
© 1992 Pergamon Press Ltd. Reproduction not permitted
settlements are correctly predicted. A small error in predicted rate of settlement results from ignoring changes in radial properties. 925175 Deformation of coastal silty soils Cuellar, V; Oteo, C; Olalla, C; Monte, J L Proc lOth European Conference on Soil Mechanics and Foundation Engineering, Florence, 26.30 May 1991 VI, P5760. Publ Rotterdam: A A Balkema, 1991 Tests were carried out to characterise the compressibility and consolidation behaviour of soft silty sands and underlying normally consolidated stratified clays around Huelva harbour, Spain. Pore pressure dissipation tests were carried out using a piezocone penetrometer and permeability and consolidation parameters compared to those from a self boring penetrometer and laboratory one-dimensional consolidation tests on undisturbed samples. Results are consistent with reported data from trial embankments in the same soil formation. 925176 End-of-primary consolidation of peat Edil, T C; Fox, P J; Lan, L T Proc lOth European Conference on Soil Mechanics and Foundation Engineering, Florence, 26-30 May 1991 V1, P6568. Publ Rotterdam: A A Balkema, 1991 A series of end-of-primary (EOP) and long term oedometer tests was carried out on thick and thin specimens of a fibrous peat with the same aspect ratio. The applicability of the EOP concept for peats is examined on the basis of the test results. Conventional curve fitting techniques for organic soils were unreliable for the peat. No significant difference was found between EOP compression curves from long duration and EOP tests. EOP tests on samples of different thickness indicated a tendency to deviate from the unique EOP concept in the virgin loading stage. The use of thin specimens to evaluate EOP void ratio may be questionable. 925177 Relationship between the mineralogical data and the swelling of the marlstone of the Asco Power Plant foundation Esteban, F; Sagaseta, C; Soriano, A Proc lOth European Conference on Soil Mechanics and Foundation Engineering, Florence, 26-30 May 1991 V1, P6972. Publ Rotterdam: A d Balkema, 1991
The effects of ageing on the mechanical properties of marine clays was studied by comparing behaviour of undisturbed and remoulded samples. Compression index and secondary compression index of natural aged clays show peak values when consolidation pressure is slightly higher than consolidation yield stress. A compression index ratio is defined as a representation of ageing effects for natural clays. Values of this parameter for Japanese alluvial clays and aged Canadian clays are compared. Consolidation of clay slurries at 75 deg C followed by cooling produces samples similar mechanically to lightly aged clays. Accelerated cementation is the probable cause of this effect.
Free swell tests were carried out on unaltered and remoulded samples of the Tertiary gypsum-marl evaporitic rocks from beneath the foundations of the Asco II nuclear plant in Spain. Relations between mineralogical composition and swelling behaviour have been examined. The importance of the presence of sulphates, in particular anhydrite, to longer term swelling is described.
925174 Sand drain induced subsidence of a peat McNulty, E G Proc 4th International Conference on Land Subsidence, Houston, 12-17 May 1991 P333-340. Publ IAHS Press: Wallingford, 1991
925178 Pore pressure dissipation of highly fissured clays Federico, F; Musso, A Proc lOth European Conference on Soil Mechanics and Foundation Engineering, Florence, 26-30 May 1991 VI, P7782. Publ Rotterdam: A A Balkema, 1991
It has been claimed that sand drains do not accelerate the consolidation of peat because of the predominance of creep effects, and in addition the increase in effective stress causes decrease in radial hydraulic conductivity, which will in fact retard settlement. Predictions from nonlinear, large scale finite element analysis are compared to field data. If field disturbance due to construction activity is taken into account, field
One dimensional consolidation of an intensely fissured clay has been studied, with fluid exchange between fissures and matrix pores taken into account. Because of the role of the fissures in the dual porosity medium, the layer thickness does not have the same important effect as in classical Terzaghi theory. The extrapolation of small sample laboratory results to field scale is questionable. An analogue model with elastic
© 1992 Pergamon Press Ltd. Reproduction not permitted