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886165 Instrumentation and in-situ testing on reclamation projects
281A at the same depths for comparison. Results show that coefficient of compressibility and coefficient of consolidation determined in the laboratory are not significantly affected by sample size. Estimate of in situ coefficient of consolidation is best made from laboratory determined coefficient of compressibility, and from in situ permeability measurement. 886159 Tenth Canadian Geotechnical Colloquium: recent developments in consolidation of natural clay
Leroueil, S Can Geotech J V25, Nl. Feb 1988, P85-107 A global analysis of the consolidation of natural clays, considering the process to be combined effects of compressibility and permeability, is presented. The compressibility or stress-strain curve followed is strongly influenced, both in the laboratory and in situ, by the strain rate. The self-boring permeameter appears to be an excellent tool for permeability measurement, although in homogeneous clays direct measurement in the laboratory also gives representative results. The coefficients of consolidation determined graphically strongly underestimate the in situ coefficient. The consolidation must thus be analysed by considering compressibility and permeability parameters separately. Auth. 117 refs. 886160 Closed-form heave solutions for expansive soils
Rao, R R; Rahardjo, H; Fredlund, D G J Geotech Engng Div ASCE V114. N5, May 1988, P573-588 A brief review of heave prediction theory is presented. The importance of adjusting laboratory test results to account for sampling disturbance is emphasised. Closed form solutions are presented for a homogeneous soil deposit whose swelling pressure is constant with depth for three cases: wetting from top to a specified depth; partial excavation of the soil profile; and partial removal of the soil profile and replacement with nonexpansive backfill. 886161 Permeability and compressibility induced consolidation
of slurries from seepage-
Huerta, A; Kriegsmann, GA; Krizek, R J J Geotech Engng Div ASCE V114, N5, May 1988, P614-627 A one dimensional mathematical model has been developed of the consolidation of sedimented slurries or very soft clays by seepage of water into an underlying drainage blanket. It may be solved to obtain final thickness of a sediment subjected to a constant piezometric head or to derive permeability and compressibility relations for a soft sediment. The model shows permeability affects both time to reach the steady state condition and the nature of the condition itself. An illustrated example is presented. 886162 Oedometer testing at the Norwegian Geotechnical Institute
Sandbaekken, G; Berre, T; Lacasse, S Norw Geotech Inst Pub1 N168, 1987, 25P An automated continuous loading oedometer test device has been developed. The oedometer cell, specimen preparation techniques, test procedures for incremental and continuous loading and test interpretation are described. Typical results and soil parameters inferred from the test are presented. The coefficient of consolidation is determined from the coefficient of permeability and tangent constrained modulus of the stressstrain curve. 0
886163 Profiling stress history from piezocone soundings
Mayne, P W; Holtz, R D Soils Found V28. Nl, March 1988, P16-28 The use of piezocone data for characterising the stress history of clay deposits is evaluated using data from 36 well documented sites. The normalised pore pressure parameters are shown to generally decrease with increased overconsolidation ratio (OCR), whilst the normal&d excess pore pressure to effective overburden ratio increases with OCR. There is an apparent trend between preconsolidation pressure and excess pore pressure. It is recommended that the porous element be located on the cone face to give standardised pore pressure readings. 67 refs. 886164 Settlement behaviour of improved ground with a vertical drain system
Kumamoto, N; Sumioka, N; Moriwaki, T; Yoshikuni, H Soit%Found V28, Nl, March 1988, P77-88 Numerical experiments, using a finite element program based on the Cam-clay theory, were conducted to investigate settlement behaviour of ground partially improved by the installation of vertical drains. Results verify that settlement rate of such ground lags behind the rate predicted by design theory, and that the degree of lag is more noticeable in areas closer to the edges of the improved area and in the later stages of consolidation. A method for determining the range of area requiring vertical drain installation to improve conditions, using the results of the numerical analysis, is presented. 886165 Instrumentation
and in-situ testing on reclamation projects
Choa, V Proc 4th InternationaI GeoteehnicaI Seminar, Field Instrumentation and In-situ Measurements, Singapore, 25-27 November 1986 P219-233. Pub1 Singapore: NTI, 1986 Extensive monitoring before, during and after reclamation work in Singapore is described. A pre-reclamation geophysical survey was used to identify areas underlain by soft marine clay, and the results of laboratory and in situ soil tests used to determine expected slope stability and settlement rate. During reclamation, fill properties were determined and the operation was monitored using settlement gauges, inclinometers and piezometers. In situ testing consisted of vane shear tests and piston sampling inside boreholes. Post reclamation improvement was necessary and was achieved using vertical drains and surcharge. The importance of monitoring is stressed throughout. 886166 Initial results from an in-situ consolidometer
Vitayasupakom, V; Banerjee, S In: Use of In Situ Tests in GeotechnicaI Engineering (papers to the Conference, Bhcksburg, 23-25 June 1986) P1249-1262. Pub1 New York: ASCE. 1986 (ASCE Geotechnical Special Publication No 6) A selfboring consolidometer which measures consolidation parameters using electroosmosis is described. Pilot tests were carried out in a soft clay deposit for which one dimensional consolidation data were available from conventional laboratory testing. Consolidation parameters obtained by the two methods were in reasonable agreement. Electroosmotic conductivity measured directly on undisturbed specimens in the laboratory was in reasonable agreement with that calculated indirectly from consolidometer readings.
1988 Pergamon Press plc. Reproduction
not permitted
Leroueil, S Can Geotech J V25, Nl. Feb 1988, P85-107 A global analysis of the consolidation of natural clays, considering the process to be combined effects of compressibility and permeability, is presented. The compressibility or stress-strain curve followed is strongly influenced, both in the laboratory and in situ, by the strain rate. The self-boring permeameter appears to be an excellent tool for permeability measurement, although in homogeneous clays direct measurement in the laboratory also gives representative results. The coefficients of consolidation determined graphically strongly underestimate the in situ coefficient. The consolidation must thus be analysed by considering compressibility and permeability parameters separately. Auth. 117 refs. 886160 Closed-form heave solutions for expansive soils
Rao, R R; Rahardjo, H; Fredlund, D G J Geotech Engng Div ASCE V114. N5, May 1988, P573-588 A brief review of heave prediction theory is presented. The importance of adjusting laboratory test results to account for sampling disturbance is emphasised. Closed form solutions are presented for a homogeneous soil deposit whose swelling pressure is constant with depth for three cases: wetting from top to a specified depth; partial excavation of the soil profile; and partial removal of the soil profile and replacement with nonexpansive backfill. 886161 Permeability and compressibility induced consolidation
of slurries from seepage-
Huerta, A; Kriegsmann, GA; Krizek, R J J Geotech Engng Div ASCE V114, N5, May 1988, P614-627 A one dimensional mathematical model has been developed of the consolidation of sedimented slurries or very soft clays by seepage of water into an underlying drainage blanket. It may be solved to obtain final thickness of a sediment subjected to a constant piezometric head or to derive permeability and compressibility relations for a soft sediment. The model shows permeability affects both time to reach the steady state condition and the nature of the condition itself. An illustrated example is presented. 886162 Oedometer testing at the Norwegian Geotechnical Institute
Sandbaekken, G; Berre, T; Lacasse, S Norw Geotech Inst Pub1 N168, 1987, 25P An automated continuous loading oedometer test device has been developed. The oedometer cell, specimen preparation techniques, test procedures for incremental and continuous loading and test interpretation are described. Typical results and soil parameters inferred from the test are presented. The coefficient of consolidation is determined from the coefficient of permeability and tangent constrained modulus of the stressstrain curve. 0
886163 Profiling stress history from piezocone soundings
Mayne, P W; Holtz, R D Soils Found V28. Nl, March 1988, P16-28 The use of piezocone data for characterising the stress history of clay deposits is evaluated using data from 36 well documented sites. The normalised pore pressure parameters are shown to generally decrease with increased overconsolidation ratio (OCR), whilst the normal&d excess pore pressure to effective overburden ratio increases with OCR. There is an apparent trend between preconsolidation pressure and excess pore pressure. It is recommended that the porous element be located on the cone face to give standardised pore pressure readings. 67 refs. 886164 Settlement behaviour of improved ground with a vertical drain system
Kumamoto, N; Sumioka, N; Moriwaki, T; Yoshikuni, H Soit%Found V28, Nl, March 1988, P77-88 Numerical experiments, using a finite element program based on the Cam-clay theory, were conducted to investigate settlement behaviour of ground partially improved by the installation of vertical drains. Results verify that settlement rate of such ground lags behind the rate predicted by design theory, and that the degree of lag is more noticeable in areas closer to the edges of the improved area and in the later stages of consolidation. A method for determining the range of area requiring vertical drain installation to improve conditions, using the results of the numerical analysis, is presented. 886165 Instrumentation
and in-situ testing on reclamation projects
Choa, V Proc 4th InternationaI GeoteehnicaI Seminar, Field Instrumentation and In-situ Measurements, Singapore, 25-27 November 1986 P219-233. Pub1 Singapore: NTI, 1986 Extensive monitoring before, during and after reclamation work in Singapore is described. A pre-reclamation geophysical survey was used to identify areas underlain by soft marine clay, and the results of laboratory and in situ soil tests used to determine expected slope stability and settlement rate. During reclamation, fill properties were determined and the operation was monitored using settlement gauges, inclinometers and piezometers. In situ testing consisted of vane shear tests and piston sampling inside boreholes. Post reclamation improvement was necessary and was achieved using vertical drains and surcharge. The importance of monitoring is stressed throughout. 886166 Initial results from an in-situ consolidometer
Vitayasupakom, V; Banerjee, S In: Use of In Situ Tests in GeotechnicaI Engineering (papers to the Conference, Bhcksburg, 23-25 June 1986) P1249-1262. Pub1 New York: ASCE. 1986 (ASCE Geotechnical Special Publication No 6) A selfboring consolidometer which measures consolidation parameters using electroosmosis is described. Pilot tests were carried out in a soft clay deposit for which one dimensional consolidation data were available from conventional laboratory testing. Consolidation parameters obtained by the two methods were in reasonable agreement. Electroosmotic conductivity measured directly on undisturbed specimens in the laboratory was in reasonable agreement with that calculated indirectly from consolidometer readings.
1988 Pergamon Press plc. Reproduction
not permitted