Laboratory testing and in situ behaviour of peat as embankment foundation

1984 ◽  
Vol 21 (2) ◽  
pp. 322-337 ◽  
Author(s):  
G. Lefebvre ◽  
P. Langlois ◽  
C. Lupien ◽  
J.-G. Lavallée
Keyword(s):  
Pore Pressure ◽  
Laboratory Testing ◽  
Lateral Displacement ◽  
Laboratory Data ◽  
Constant Load ◽  
Log P ◽  
Creep Tests ◽  
Special Equipment ◽  
Fibrous Peat ◽  
Pore Pressure Response

Intact block samples of fibrous peat have been obtained using special equipment from two different sites in the James Bay territory in Quebec. Instrumented test fills were subsequently built at those two sites and the observed behaviour was used to check the laboratory data. The laboratory testing program has included standard 24 h incremental tests and stage creep tests where constant loads were applied for periods of about 30 d. Pore pressure and direct permeability measurements were conducted in most of the tests.The tests have been interpreted using the classical e − log p curves or the tangent modulus approach. The evaluation of compression with time under a constant load has allowed the distinction between primary and secondary consolidation. A certain lag in pore pressure response has been observed and related to incomplete saturation. The coefficient of permeability decreases rapidly with compression as indicated by direct measurements and pore pressure dissipation.The comparison with field observation shows that the 24 h incremental oedometric compression test permits a reasonable prediction of the average settlements at the end of primary consolidation provided the lateral displacement during construction is small. It also shows that the secondary compression observed in the field is about twice what was observed in the laboratory but both show a linear relation with the logarithm of time.Keywords: peat, sampling, compressibility, consolidation, secondary consolidation, permeability, laboratory tests, field behaviour.

Prediction of impending failure of embankments on soft ground

2003 ◽  
Vol 40 (1) ◽  
pp. 209-220 ◽  
Author(s):  
Gavan Hunter ◽  
Robin Fell
Keyword(s):  
Pore Pressure ◽  
Factor Of Safety ◽  
Ground Deformation ◽  
Lateral Displacement ◽  
Deformation Behaviour ◽  
Vertical Displacement ◽  
Pressure Response ◽  
Excess Pore Pressure ◽  
Soft Ground ◽  
Pore Pressure Response

The deformation behaviour and excess pore pressure response of 13 well-monitored embankments on soft ground that were constructed to failure have been analyzed. The analysis shows that by monitoring lateral displacement at the toe of the embankment and vertical displacement at the toe and about 5 m beyond the toe, the onset of impending failure of embankments on soft ground can be detected while the slope is at about 70–90% of the failure height. This equates to an actual factor of safety of around 1.25. Monitoring of borehole inclinometers at the toe of the embankment, cracking of the embankment, and the pore pressure response and deformation during pauses in construction can provide useful additional data for detection of an impending failure.Key words: embankment on soft ground, deformation, pore pressure, failure, factor of safety.

scholarly journals Cutting Resistance Laboratory Testing Methodology for Underwater Coal Mining

Minerals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 564
Author(s):  
Vladimir Čebašek ◽  
Veljko Rupar ◽  
Stevan Đenadić ◽  
Filip Miletić
Keyword(s):  
Coal Mining ◽  
Laboratory Testing ◽  
Water Pressure ◽  
Laboratory Data ◽  
Working Environment ◽  
Laboratory Research ◽  
Surrounding Water ◽  
Cutting Resistance ◽  
Testing Methodology

The bucket-wheel dredge “Kovin I” for underwater coal mining with bucket-wheel type UCW-450 has been in operation for over 20 years. Based on analyzing the bucket-wheel dredger performance, productivity, maintenance costs, and reliability, a rational decision was made: to rehabilitate the most essential parts of the dredge, including the bucket wheel and the gearbox. However, the selection and construction of the excavator parts were performed on the ground of available laboratory data for digging resistance. The data itself was determined by the testing methodology that did not include the influence of surrounding water pressure at a certain depth of mining. According to the previous findings, it was necessary to develop a specific research and testing program that would involve appropriate laboratory testing of the geomechanical parameters. These were to represent the influence of hydrostatic water pressure on the working environment—coal. Nevertheless, geomechanical laboratory research tests were initially modified to provide reliable data of cutting resistance, especially in the water under different hydrostatic pressures, fully simulating the “in situ” working conditions of mining, i.e., cutting.

Field observations on the load–strain–time behaviour of geogrid reinforcement

1994 ◽  
Vol 31 (4) ◽  
pp. 564-569 ◽  
Author(s):  
R.J. Fannin
Keyword(s):  
Tensile Strength ◽  
Field Data ◽  
Constant Load ◽  
Reinforced Soil ◽  
Mean Annual Temperature ◽  
Creep Tests ◽  
Geogrid Reinforcement ◽  
Rapid Loading ◽  
Strip Test ◽  
Relationship Of

Field data are reported that describe the load–strain–time relationship of geogrid reinforcement in a reinforced soil structure. The data are for a period exceeding 5 years and reveal a continued strain in the reinforcement, which occurs at nearly constant load. The response to loading is attributed to creep of the polymeric material. A comparison of the field data with laboratory isochronous load–strain curves, from rapid loading creep tests performed at a temperature similar to the mean annual temperature in the backfill soil, shows the curves describe very well the magnitude of creep strains observed in the field. Implications of the load–strain–time performance data are assessed with reference to the use in design of a tensile strength established from the rapid-loading creep test and wide-width strip test. The need to clarify, in design of polymeric reinforced soil structures, between a safe and allowable tensile strength is emphasized. Key words : reinforced soil, geogrid, creep, tensile strength, strain.

scholarly journals A Comparison between CoNiCrAlY Bond Coat and Zirconia Plasma Sprayed Coatings on Creep Tests

2008 ◽  
Vol 591-593 ◽  
pp. 30-35
Author(s):  
Danieli A.P. Reis ◽  
Carlos de Moura Neto ◽  
Antônio Augusto Couto ◽  
Cosme Roberto Moreira Silva ◽  
Francisco Piorino Neto ◽  
...  
Keyword(s):  
Bond Coat ◽  
Ceramic Coating ◽  
Constant Load ◽  
Creep Tests ◽  
Engineering Ceramic ◽  
Wide Range ◽  
Plasma Sprayed Coatings ◽  
Plasma Sprayed ◽  
Engine Components ◽  
Sprayed Coatings

Thermomechanical and electrical properties of zirconia-based ceramics have led to a wide range of advanced and engineering ceramic applications like solid electrolyte in oxygen sensors, fuel cells and furnace elements and its low thermal conductivity has allowed its use for thermal barrier coatings for aerospace engine components. A comparison between CoNiCrAlY bond coat and zirconia plasma sprayed coatings on creep tests of the Ti-6Al-4V alloy was studied. The material used was commercial Ti-6Al-4V alloy. Yttria (8 wt.%) stabilized zirconia (YSZ) with a CoNiCrAlY bond coat was atmospherically plasma sprayed on Ti-6Al-4V substrates by Sulzer Metco Type 9 MB. Constant load creep tests were conducted on a standard creep machine in air on coated samples, at stress levels of 520 MPa at 500°C to evaluate the oxidation protection on creep of the Ti-6Al-4V alloy. Results indicate that the creep resistance of the ceramic coating was greater than metallic coating.

An investigation of the creep processes in tin and aluminum using a depth-sensing indentation technique

1992 ◽  
Vol 7 (3) ◽  
pp. 627-638 ◽  
Author(s):  
V. Raman ◽  
R. Berriche
Keyword(s):  
Stress Exponent ◽  
Constant Load ◽  
Indentation Creep ◽  
Depth Sensing ◽  
Creep Tests ◽  
Si Substrates ◽  
Uniaxial Creep ◽  
Rate Versus ◽  
Deformation Properties ◽  
Film Substrate

Constant load creep experiments were conducted using a depth-sensing indentation instrument with indentation depths in the submicron range. Experiments were conducted on polycrystalline Sn and sputtered Al films on Si substrates. The results show that the plastic depth versus time curves and the strain rate versus stress plots from these experiments are analogous to those obtained from conventional creep experiments using bulk specimens. The value of the stress exponent for Sn is close to the reported values from uniaxial creep tests. Tests on Al films showed that the stress exponent is dependent on the indentation depth and is governed by the proximity to the film/substrate interface. Load change experiments were also performed and the data from these tests were analyzed. It is concluded that indentation creep experiments may be useful in elucidating the deformation properties of materials and in identifying deformation mechanisms.

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