Pure elastic stiffness of sand represented by response envelopes derived from cyclic triaxial tests with local strain measurements

2020 ◽  
Vol 15 (8) ◽  
pp. 2075-2088 ◽  
Author(s):  
Lukas Knittel ◽  
Torsten Wichtmann ◽  
Andrzej Niemunis ◽  
Gerhard Huber ◽  
Edgar Espino ◽  
...  
Keyword(s):  
Local Strain ◽  
Elastic Stiffness ◽  
Triaxial Tests ◽  
Cyclic Triaxial ◽  
Cyclic Triaxial Tests ◽  
Strain Measurements

scholarly journals An appraisal of end conditions in advanced monotonic and cyclic triaxial testing on a range of geomaterials

2019 ◽  
Vol 92 ◽  
pp. 02007
Author(s):  
Ken Vinck ◽  
Tingfa Liu ◽  
Emil Ushev ◽  
Richard J. Jardine
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Pressure Sensors ◽  
Local Strain ◽  
Triaxial Tests ◽  
Triaxial Testing ◽  
Cyclic Triaxial ◽  
Cyclic Triaxial Tests ◽  
End Conditions

Compressing samples between rigid platens, as in triaxial testing, induce non-uniform specimen stress, strain and pore water distributions. Although well recognised historically, the effects of such platen restraints are often disregarded or overlooked when performing or interpreting monotonic and cyclic experiments. This paper presents an updated appraisal of end conditions based on laboratory experiments run on sand, glacial till, intact and puttified chalk as part of offshore piling research projects. Monotonic and cyclic triaxial tests are reported that incorporated local strain and pore pressure sensors and a range of platen configurations. New insights are reported regarding the small-to-large behaviour and undrained cyclic pore water pressure measurement.

On the “elastic” stiffness in a high-cycle accumulation model for sand: a comparison of drained and undrained cyclic triaxial tests

2010 ◽  
Vol 47 (7) ◽  
pp. 791-805 ◽  
Author(s):  
Torsten Wichtmann ◽  
Andrzej Niemunis ◽  
Theodor Triantafyllidis
Keyword(s):  
Bulk Modulus ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Volumetric Strain ◽  
Elastic Stiffness ◽  
Plastic Strain Rate ◽  
Triaxial Tests ◽  
Strain Accumulation ◽  
Cyclic Triaxial ◽  
Cyclic Triaxial Tests

High-cycle accumulation (HCA) models may be used for the prediction of settlements or stress relaxation in soils due to a large number of cycles (N > 103) with a relatively small-strain amplitude (εampl < 10−3). This paper presents a discussion of the elastic stiffness, [Formula: see text], used in the basic constitutive equation of an HCA model, [Formula: see text], where [Formula: see text] is the trend of effective stress, [Formula: see text] is the trend of strain, [Formula: see text] is the rate of strain accumulation, and [Formula: see text] is the plastic strain rate. [Formula: see text] interrelates the “trends” of stress and strain evolution. For the experimental assessment of the bulk modulus, [Formula: see text], the rate of pore-water pressure accumulation, [Formula: see text], in undrained cyclic triaxial tests and the rate of volumetric strain accumulation, [Formula: see text], in drained cyclic tests have been compared. The pressure-dependent bulk modulus, K, was quantified from 15 pairs of drained and undrained tests with different consolidation pressures and stress amplitudes. It is demonstrated that both the curves [Formula: see text] in the drained tests and u(N) in the undrained tests are well predicted by the authors’ HCA model if the elastic stiffness is determined using the method described in the present paper. A simplified determination of K from the unloading and reloading curve in an oedometric compression test is discussed.

Effect of the loading frequency on the sand liquefaction behaviour in cyclic triaxial tests

2021 ◽  
Vol 147 ◽  
pp. 106779
Author(s):  
Zhehao Zhu ◽  
Feng Zhang ◽  
Qingyun Peng ◽  
Jean-Claude Dupla ◽  
Jean Canou ◽  
...  
Keyword(s):  
Triaxial Tests ◽  
Loading Frequency ◽  
Cyclic Triaxial ◽  
Cyclic Triaxial Tests ◽  
Sand Liquefaction

Importance of Measuring Local Strains in Cyclic Triaxial Tests on Granular Materials

2009 ◽  
pp. 288-288-15 ◽  
Author(s):  
F Tatsuoka ◽  
S Teachavorasinskun ◽  
J Dong ◽  
Y Kohata ◽  
T Sato
Keyword(s):  
Granular Materials ◽  
Triaxial Tests ◽  
Cyclic Triaxial ◽  
Cyclic Triaxial Tests ◽  
Local Strains

scholarly journals Soil liquefaction as an identification test

2019 ◽  
Vol 92 ◽  
pp. 08008
Author(s):  
Bozana Bacic ◽  
Ivo Herle
Keyword(s):  
Pore Water ◽  
Laboratory Testing ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Initial Density ◽  
Soil Liquefaction ◽  
Triaxial Tests ◽  
Cyclic Triaxial ◽  
Cyclic Triaxial Tests ◽  
Identification Test

Time-consuming and complicated investigations of soil liquefaction in cyclic triaxial tests are the most common way of laboratory analysis of this phenomenon. Moreover, the necessary equipment for the performance of cyclic triaxial tests is very expensive. Much simpler method for laboratory testing of the soil liquefaction has been developed at the Institute of Geotechnical Engineering at the TU Dresden. This method takes into account the pore water pressure build-up during cyclic shearing within a short time period. During the test, the soil sample is subjected to horizontal cyclic loading and the generated pore water pressure is measured. In the first series of these experiments, a dependence of the pore water pressure buildup on the initial density of soil could be observed, as expected. When comparing different soils, it is shown that the tendency to liquefaction depends also on the granulometric properties (e.g. grain size distribution) of the soil. The aim of the further development is to establish a simple identification test for laboratory testing of the soil liquefaction.

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