Estimating coefficient of consolidation from piezocone tests

1992 ◽  
Vol 29 (4) ◽  
pp. 539-550 ◽  
Author(s):  
P. K. Robertson ◽  
J. P. Sully ◽  
D. J. Woeller ◽  
T. Lunne ◽  
J. J. M. Powell ◽  
...  
Keyword(s):  
Pore Pressure ◽  
Published Data ◽  
Pressure Data ◽  
Cone Penetration ◽  
Coefficient Of Consolidation ◽  
New Correlation ◽  
Coefficient Of Permeability ◽  
North And South America ◽  
North And South

Data have been reviewed from sites in Europe and North and South America as well as published data from South Africa. The review has concentrated on dissipation data from piezocone tests (CPTU) to compare predicted coefficient of consolidation and permeability values using published interpretation techniques with available reference values. The results of this review have shown that the theoretical solutions provide reasonable estimates of the in situ coefficient of consolidation. Results were evaluated for pore-pressure data from different locations on the piezocone, and the least scatter in results was obtained with the pore-pressure element location immediately above the cone tip. A new correlation has been proposed to estimate in situ horizontal coefficient of permeability (kh) from piezocone dissipation data. Key words : in situ, coefficient consolidation, cone penetration test, permeability.

In situ estimation of the coefficient of consolidation in clays

1990 ◽  
Vol 27 (1) ◽  
pp. 58-67 ◽  
Author(s):  
Mohammed G. Kabir ◽  
Alan J. Lutenegger
Keyword(s):  
Key Words ◽  
Pore Pressure ◽  
Reference Values ◽  
Time Factors ◽  
In Situ Tests ◽  
Coefficient Of Consolidation ◽  
Oedometer Test ◽  
Undisturbed Samples ◽  
Oedometer Tests

An investigation was conducted to demonstrate the applicability of cylindrical piezocone and flat piezoblade tests for providing reliable estimates of the coefficient of consolidation in clays. Coefficients of consolidation were calculated from piezocone dissipation tests for different degrees of consolidation using theoretical time factors to provide a comparison with laboratory oedometer tests. Three techniques were developed to calculate the coefficient of consolidation from piezoblade dissipation tests. Results from in situ pore pressure dissipation tests were compared with laboratory oedometer tests performed on undisturbed samples oriented in both the vertical and horizontal directions, to provide reference values of cv and ch. The results of investigations conducted at several clay sites are presented. Key words: in situ tests, piezocone, piezoblade, coefficient of consolidation, oedometer test, clays.

scholarly journals In-situ measurement of the strength of deforming subglacial till

1994 ◽  
Vol 40 (136) ◽  
pp. 497-503 ◽  
Author(s):  
Neal R. Iverson ◽  
Peter Jansson ◽  
Roger Leb. Hooke
Keyword(s):  
Pore Pressure ◽  
Residual Strength ◽  
Plastic Material ◽  
Excess Pore Pressure ◽  
Cone Penetration ◽  
New Instrument ◽  
Average Residual ◽  
Basal Till ◽  
Source Of Error

AbstractThe shear strength of deforming till beneath Storglaciären, Sweden, was continuously measured with a new instrument, a “dragometer”. A cylinder with conical ends, roughened with till from the glacier bed, was dragged through the till, and the force on the cylinder was recorded. Consistent with studies of cone penetration in soils, it was assumed that the till behaves as a Coulomb plastic material. This allows the residual strength of the till to be calculated from the measured force. Results from laboratory experiments confirm the validity of the analytical procedure.The average residual strength of the till was ∼55 kPa. A source of error is the potential generation of pore pressure in excess of hydrostatic ahead of the cylinder, which could significantly weaken the till. Calculations indicate that excess pore pressure did not develop during the experiment, but could develop during similar experiments beneath rapidly sliding glaciers with less permeable basal till layers.

scholarly journals In-situ measurement of the strength of deforming subglacial till

1994 ◽  
Vol 40 (136) ◽  
pp. 497-503 ◽  
Author(s):  
Neal R. Iverson ◽  
Peter Jansson ◽  
Roger Leb. Hooke
Keyword(s):  
Pore Pressure ◽  
Residual Strength ◽  
Plastic Material ◽  
Excess Pore Pressure ◽  
Cone Penetration ◽  
New Instrument ◽  
Average Residual ◽  
Basal Till ◽  
Source Of Error

AbstractThe shear strength of deforming till beneath Storglaciären, Sweden, was continuously measured with a new instrument, a “dragometer”. A cylinder with conical ends, roughened with till from the glacier bed, was dragged through the till, and the force on the cylinder was recorded. Consistent with studies of cone penetration in soils, it was assumed that the till behaves as a Coulomb plastic material. This allows the residual strength of the till to be calculated from the measured force. Results from laboratory experiments confirm the validity of the analytical procedure.The average residual strength of the till was ∼55 kPa. A source of error is the potential generation of pore pressure in excess of hydrostatic ahead of the cylinder, which could significantly weaken the till. Calculations indicate that excess pore pressure did not develop during the experiment, but could develop during similar experiments beneath rapidly sliding glaciers with less permeable basal till layers.

scholarly journals Formation Pore Pressure Variation of the Neocomian Sedimentary Succession (the Fahliyan Formation) in the Abadan Plain Basin, SW of Iran

Geofluids ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-13 ◽  
Author(s):  
Bahman Soleimani ◽  
Mohammad Hassani-Giv ◽  
Iraj Abdollahi fard
Keyword(s):  
Pore Pressure ◽  
Middle Part ◽  
Burial Depth ◽  
Pressure Data ◽  
Pressure Step ◽  
Data Points ◽  
Sedimentary Succession ◽  
Pressure Regime ◽  
Formation Pore Pressure

The Neocomian Fahliyan Formation is one of the important oil reservoirs in the Abadan Plain Basin, SW of Iran. To evaluate the pore pressure regime of the Fahliyan reservoir, 164 in situ pressure data points (MDT, XPT, and RFT) were analyzed from seven wells belonging to six oilfields. The pressure versus depth plot revealed that the Fahliyan reservoir is highly overpressured in all fields. The formation was characterized as a multilayered stacked reservoir with different pore pressure decreasing downward in a step-wise manner. Also, there is a major pressure step in the middle part of the reservoir, suggesting the presence of a regional efficient seal dividing the reservoir into two stacked compartments, where the upper compartment is more overpressured than the lower one. The stepped pressure pattern of the Fahliyan Formation is a regional phenomenon controlled by a factor governed regionally, the depositional condition, and facies lateral changes during the deposition of shallowing upward sequence of the Fahliyan reservoir. In addition, direct relationship is observed between the reservoir pressure and burial depth. This matter could amplify the initially generated overpressure state more possible due to dewatering of sediments and by-pass product of oil migration from Garau source rock to the Fahliyan reservoir.

scholarly journals A comparison of New Zealand and overseas white clover cultivars under grazing in New Zealand

2015 ◽  
Vol 77 ◽  
pp. 51-56 ◽  
Author(s):  
K.H. Widdup ◽  
J.L. Ford ◽  
G.R. Cousins ◽  
D.R. Woodfield ◽  
J.R. Caradus ◽  
...  
Keyword(s):  
New Zealand ◽  
White Clover ◽  
Meta Analysis ◽  
Published Data ◽  
Local Conditions ◽  
Southern France ◽  
Forage Value ◽  
North And South America ◽  
North And South ◽  
Benchmarking System

A large number of white clover cultivars bred both in New Zealand and overseas are available for use by New Zealand pastoral farmers. Unfortunately, there is little published data on the merits of many of these cultivars under grazing in New Zealand. Data from a series of trials established in the Manawatu between 1996 and 2005 containing a range of cultivars from Europe, the Mediterranean, North and South America and New Zealand were used in a meta-analysis to assess the general adaptive yield and persistence potential of these contrasting cultivar types. All trials were maintained over 2 to 4 years, and revealed significant cultivar effects. Overall, New Zealand bred cultivars showed better adaptation than overseas cultivars. However, overseas cultivars containing Mediterranean germplasm, particularly from southern France, Italy and Syria exhibited beneficial features in the trials, and many recently bred New Zealand cultivars contain germplasm from these origins. In addition to using the appropriate parent germplasm when developing cultivars, it is equally important to evaluate and select under local conditions, in competition with grass, under grazing, over multiple environments and years. New Zealand farmers may benefit from an industrywide benchmarking system for white clover cultivars, possibly by incorporation into the DairyNZ Forage Value Index. Keywords: white clover, cultivars, germplasm, local, overseas, adaptation

In situ dynamic piezocone penetrometer tests in natural clayey soils — a reappraisal of strain-rate corrections

2014 ◽  
Vol 51 (3) ◽  
pp. 272-288 ◽  
Author(s):  
Alois Steiner ◽  
Achim J. Kopf ◽  
Jean-Sebastien L’Heureux ◽  
Stefan Kreiter ◽  
Sylvia Stegmann ◽  
...  
Keyword(s):  
Strain Rate ◽  
Pore Pressure ◽  
Penetration Rate ◽  
Sediment Cores ◽  
Penetration Resistance ◽  
Cone Penetration ◽  
Near Surface ◽  
Static Tests ◽  
Cone Penetration Resistance

Cone penetration testing with pore pressure measurement (CPTU) is a cost- and time-efficient way of collecting in situ geotechnical parameters of near-surface marine soils for cable and pipeline tracks, offshore foundations, and geohazard identification. The measured dynamic CPTU parameters (cone penetration resistance, sleeve friction, pore pressure) are higher than the measured static CPTU parameters. This mismatch is caused by the different penetration rates used for dynamic and static CPTU tests (dynamic tests have up to 500 times higher penetration rates than the static tests; i.e., with the commonly used 2 cm/s penetration rate). This study presents comprehensive Calypso piston and gravity core as well as dynamic and static CPTU datasets acquired in the landslide-prone Sørfjorden area (Finneidfjord, northern Norway). The fjord-marine sediments at the study site are characterized as normally consolidated to slightly over consolidated clay-dominated soils with embedded layers of sandy silt to sand. The dynamic CPTU results were corrected to match the nearby static CPTU (i.e., distance less than 10 m) using strain-rate factors (SF) derived from three known correction methods. Based on a statistical test and visual comparison of dynamic and static CPTU profiles, the modified inverse sin-hyperbolic correction method is found to be best suited for the strain-rate correction of dynamic CPTU tests, and results in SF less than 1.35 for the corrected cone penetration resistance and up to 2.4 for the sleeve friction. Our data illustrate a positive correlation between penetration rate and penetration depth, which is governed by the consolidation state of the clays. The good agreement between SF-corrected dynamic CPTU data from 34 deployments (acquired within less than 36 h shiptime) with data obtained from static CPTU and laboratory experiments on sediment cores further demonstrates that the MARUM dynamic CPTU device is a powerful tool for characterizing the properties of surficial seafloor sediments in shallow-water environments.

Cone penetration testing in deltaic soils

1983 ◽  
Vol 20 (1) ◽  
pp. 23-35 ◽  
Author(s):  
R. G. Campanella ◽  
P. K. Robertson ◽  
D. Gillespie
Keyword(s):  
Pore Pressure ◽  
Test Site ◽  
Pressure Measurements ◽  
Test Results ◽  
Cone Penetration ◽  
In Situ Tests ◽  
Penetration Testing ◽  
Cone Penetration Testing ◽  
Laboratory Test Results

A multichannel electric cone penetrometer was used to perform a variety of in situ tests in saturated deltaic deposits.Factors affecting the tip bearing, friction sleeve stress, and pore-water pressures and their interpretation are studied and discussed. Pore pressure measurements were essential to evaluate the in situ test results. The effect of rate of penetration is discussed and the concept of effective bearing introduced as an attempt to interpret cone bearing in undrained or partially drained soil. Field values of consolidation characteristics from pore pressure decay are compared with traditional laboratory consolidation test results on undisturbed samples.The advantages of continuous electric cone logging to evaluate soil stratigraphy are demonstrated. Field and laboratory test results are presented from a test site where stabilization was used to reduce liquefaction potential of hydraulically placed sand and silt. The importance of pore pressure measurements is demonstrated along with examples and recommendations for the location of the porous element.Keywords: static cone penetration testing, in situ testing, pore pressures, consolidation, stratigraphy, liquefaction.

Gerald H. Thayer's ornithological work in St Vincent and the Grenadines, Lesser Antilles

2018 ◽  
Vol 45 (1) ◽  
pp. 21-39 ◽  
Author(s):  
James W. Wiley
Keyword(s):  
New York ◽  
New York City ◽  
West Indies ◽  
The United States ◽  
Lesser Antilles ◽  
American Museum ◽  
The West ◽  
Comparative Zoology ◽  
North And South America ◽  
North And South

Gerald Handerson Thayer (1883–1939) was an artist, writer and naturalist who worked in North and South America, Europe and the West Indies. In the Lesser Antilles, Thayer made substantial contributions to the knowledge and conservation of birds in St Vincent and the Grenadines. Thayer observed and collected birds throughout much of St Vincent and on many of the Grenadines from January 1924 through to December 1925. Although he produced a preliminary manuscript containing interesting distributional notes and which is an early record of the region's ornithology, Thayer never published the results of his work in the islands. Some 413 bird and bird egg specimens have survived from his work in St Vincent and the Grenadines and are now housed in the American Museum of Natural History (New York City) and the Museum of Comparative Zoology (Cambridge, Massachusetts). Four hundred and fifty eight specimens of birds and eggs collected by Gerald and his father, Abbott, from other countries are held in museums in the United States.

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