A numerical study of the penetration test at constant rod velocity

Tran, Quoc Anh; Chevalier, Bastien; Breul, Pierre

doi:10.1201/b17435-30

Cited by 3 publications

(7 citation statements)

References 6 publications

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“…Butlanska et al 416 (2010a) showed that rates between 2 and 50 cm/s do not change the simulation result. The 417 chosen penetration rate is also below the 1 m/s limit where dynamical effects are apparent 418 (Quezada et al, 2014;Tran et al, 2014). All the simulations employed a local non-viscous 419 damping coefficient of 0.05.…”

Section: Cpt Simulations 407mentioning

confidence: 99%

DEM modelling of cone penetration tests in a double-porosity crushable granular material

Ciantia

Arroyo²,

Butlanska³

et al. 2016

Computers and Geotechnics

114

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A three-dimensional discrete element model is used to investigate the effect of grain crushing on the tip resistance measured by cone penetration tests (CPT) in calibration chambers. To do that a discrete analogue of pumice sand, a very crushable microporous granular material, is created. The particles of the discrete model are endowed with size-dependent internal porosity and crushing resistance. A simplified Hertz-Mindlin elasto-frictional model is used for contact interaction. The model has 6 material parameters that are calibrated using one oedometer test and analogies with similar geomaterials. The calibration is validated reproducing other element tests. To fill a calibration chamber capable of containing a realistic sized CPT the discrete analogue is up-scaled by a factor of 25. CPT is then performed at two different densities and three different confinement pressures. Cone tip resistance in the crushable material is practically insensitive to initial density, as had been observed in previous physical experiments. The same CPT series is repeated but now particle crushing is disabled. The ratios of cone tip resistance between the two types of simulation are in good agreement with previous experimental comparisons of hard and crushable soils. Microscale exploration of the models indicates that crushing disrupts the buttressing effect of chamber walls on the cone. A three-dimensional discrete element model is used to investigate the effect of grain 6 crushing on the tip resistance measured by cone penetration tests (CPT) in calibration 7 chambers. To do that a discrete analogue of pumice sand, a very crushable microporous 8 granular material, is created. The particles of the discrete model are endowed with size-9 dependent internal porosity and crushing resistance. A simplified Hertz-Mindlin elasto-10 frictional model is used for contact interaction. The model has 6 material parameters that are 11 calibrated using one oedometer test and analogies with similar geomaterials. The calibration 12 is validated reproducing other element tests. To fill a calibration chamber capable of 13 containing a realistic sized CPT the discrete analogue is up-scaled by a factor of 25. CPT is 14 then performed at two different densities and three different confinement pressures. Cone tip 15 resistance in the crushable material is practically insensitive to initial density, as had been 16 observed in previous physical experiments. The same CPT series is repeated but now particle 17 crushing is disabled. The ratios of cone tip resistance between the two types of simulation are 18 in good agreement with previous experimental comparisons of hard and crushable soils. 19Microscale exploration of the models indicates that crushing disrupts the buttressing effect of 20 chamber walls on the cone. 21 KEY WORDS: 22Discrete element method, pumice sand, cone penetration, particle crushing, double porosity 23 *Manuscript Click here to view linked References 2 2

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Section: Cpt Simulations 407mentioning

confidence: 99%

DEM modelling of cone penetration tests in a double-porosity crushable granular material

Ciantia

Arroyo²,

Butlanska³

et al. 2016

Computers and Geotechnics

114

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“…shows the probability distributions of all values of tip force Fc measured between 0.05 m and 0.30 m of penetration depth obtained for three samples with different penetration rates[19]. Probability distributions of tip force Fc complies with the normal law when penetration rate is lower than 1250 mm.s -1 .…”

mentioning

confidence: 77%

“…Probability distribution of tip force Fc between 0.05 and 0.30 m of penetration distance for three samples with different rod velocities[19].…”

mentioning

confidence: 99%

Discrete modeling of penetration tests in constant velocity and impact conditions

Tran

Chevalier

Breul

2016

Computers and Geotechnics

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International audienceThe paper presents investigations on the penetration tests in granular material. A discrete numerical study is proposed for the modeling of penetration tests in constant velocity conditions and also in impact conditions. The model reproduces qualitatively the mechanical response of samples of granular material, compared to classical experimental results. Penetration tests are conducted at constant velocity and from impact, with similar penetration rates ranging from 25 mm.s-1 to 5000 mm.s-1. In constant velocity condition, the value of tip force remains steady as long as the penetration velocity induces a quasi–static regime in the granular material. However, the tip force increases rapidly in the dense flow regime corresponding to higher penetration rate. Impact tip force increases with the impact velocity. Finally, the tip forces obtained from impact penetration tests are smaller compared to the one obtained in constant velocity conditions in both quasi–static and dense flow regimes

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“…The lateral walls of the container are fixed. A study of boundary conditions with different sample sizes on this numerical model was conducted by Tran et al [14] and revealed that for a container width larger than 0.60 m, there is no effect of the lateral walls on the tip resistance anymore. A linear contact model is used along with a Coulomb friction criterion after the generation process.…”

Section: Numerical Modelmentioning

confidence: 99%

“…The numerical model of penetration tests using Discrete Element Method (DEM) used to reproduce the penetration tests in dynamic conditions is the same model as the one presented in [7]. Many authors have modeled cone penetration tests before with DEM in 2D [8][9][10][11][12][13][14][15] and in 3D [3,[16][17][18][19][20]. However, most of them modelled the penetration in static conditions, i.e.…”

Section: Introductionmentioning

confidence: 99%

Spectral Analysis of the Response of Coarse Granular Material to Dynamic Penetration Test Modelled with DEM

Tran

Chevalier

Breul

2018

Int. J. of Geosynth. and Ground Eng.

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Dynamic penetration tests are often used to determine the strength properties of surface soils. The paper presents a study on the use of spectral analysis on dynamic cone penetration tests results, modelled with Discrete Element Method. This method is applied to assess the effect of the variation of the grain size distribution of the soil on test results. A two-dimensional discrete model is used to reproduce cone penetration tests in dynamic conditions: the tip of the penetrometer is driven in the material by successive impacts of a hammer on the penetrometer. For each impact of the hammer, a curve of the load applied by the tip on the soil is obtained versus the penetration distance of the tip. The curves of the load vs. penetration traditionally used to calculate the tip resistance of the soil are analyzed with Discrete Fourier transform in order to investigate curve's shape. The effect of the variation of the grain size distribution of the soil on these curves is investigated, i.e. average particle diameter and span of particle size distribution. It was found out that the grain size distribution influences tip resistance but also the shape and oscillation modes of the curve of the stress-penetration curve. Based on these indicators, the exploitation of the load-displacement curve obtained with dynamic penetration tests could be enlarged to determine other properties of the soils.

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A numerical study of the penetration test at constant rod velocity

Cited by 3 publications

References 6 publications

DEM modelling of cone penetration tests in a double-porosity crushable granular material

DEM modelling of cone penetration tests in a double-porosity crushable granular material

Discrete modeling of penetration tests in constant velocity and impact conditions

Spectral Analysis of the Response of Coarse Granular Material to Dynamic Penetration Test Modelled with DEM

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