A Scalable and Dynamic Testbed for Conducting Penetration-Test Training in a Lab Environment

This paper describes the behaviour of two test piles (one bored and postgrouted and one simply bored, both 31.7 m long and 0.75 m in diameter) subjected to horizontal loads. These full-scale pile tests were carried out for the actual design of the pile foundation of a pier of the Evripos cable-stayed bridge. This bridge will link the Euboea Island to mainland Greece. The two piles have already been subjected to bearing capacity tests under axial loadings. The inclinometer measurements, taken during the present tests, yielded, in particular, the deformed shape of the piles as well as the bending moments. Conclusions could be drawn for the final design of the pile foundation with respect to horizontal loadings. Furthermore, various calculation methods using p–y reaction curves for cohesionless soils have been checked: the Ménard pressuremeter method, the method of the American Petroleum Institute recommendations, and the Standard penetration test method of Christoulas. These pile tests show that simple measurements, taken on construction sites, can yield interesting results on the actual behaviour of horizontally loaded piles. Key words : pile, horizontal loading, full-scale test, horizontal loads, bending moment, subgrade reaction modulus, p–y curve, cohesionless soil, Standard penetration test, pressuremeter test.

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Application of Neural Network in Identifying Soil Strata by CPT or CPTU Data

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.170-173.945 ◽

2012 ◽

Vol 170-173 ◽

pp. 945-949

Author(s):

Jun Hai Li

Keyword(s):

Neural Network ◽

Ground Improvement ◽

Thin Layers ◽

Slope Instability ◽

General Regression Neural Network ◽

Excess Pore Pressure ◽

Soil Conditions ◽

Penetration Test ◽

Piezocone Penetration Test ◽

Tip Resistance

In geotechnical engineering, assessment of the depth location of stratigraphic interfaces and the depth and thickness of thin layers can be critical in the design process. For example, stratigraphic interfaces can promote anisotropic soil strength response and potentially provide preferential slip planes that create slope instability. Similarly, the presence of thin, high permeability layers can alter groundwater flow regimes and rates of consolidation, which can hinder or accelerate methods of ground improvement. The piezocone penetration test (PCPT or CPTU) is an extension of the cone penetration test (CPT) and is able to measure cone tip resistance, sleeve friction and generated pore-water pressures simultaneously. The piezocone’s functionality is through the measured excess pore pressure profile, which reflects changes in the drainage conditions, and therefore soil conditions. In this paper the relationship between CPTU parameters and soil types and strata is analyzed, and the structure of a general regression neural network (GRNN) is designed, and the application program is programmed with MATLAB language. The results, identifying soil strata by CPTU, have confirmed that GRNN can be used to carry out the automatically identifying soil strata.

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Assessment of the range of variation of Nγ from 60 estimation methods for footings on sand

Canadian Geotechnical Journal ◽

10.1139/cgj-2012-0426 ◽

2013 ◽

Vol 50 (7) ◽

pp. 793-800 ◽

Cited By ~ 12

Author(s):

Edgar Giovanny Diaz-Segura

Keyword(s):

Friction Angle ◽

Standard Penetration Test ◽

Estimation Methods ◽

Penetration Test ◽

In Situ Tests ◽

Vertical Loading ◽

Simplified Method ◽

Bearing Capacity Factor ◽

Range Of Variation

The range of variation of the bearing capacity factor, Nγ, was assessed using 60 estimation methods for rough footings on sand subjected to static vertical loading. The influence on the Nγ values of the use of correlations for the estimation of the friction angle, [Formula: see text], derived from in situ tests was also assessed. The analysis shows a marked dependency on the methods used to determine Nγ, showing differences for the same [Formula: see text] values of up to 267% between estimated values. Uncertainty in the estimation of [Formula: see text], due to the use of correlations with in situ tests, leads to a range of variation for Nγ higher than that seen using the 60 estimation methods. Finally, given the regular use of the in situ standard penetration test (SPT) on sands, and based on a series of analyses using finite elements, a simplified method in terms of the SPT N-values is proposed for estimation of Nγ in footings on sands.

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Seismic cone penetration test and seismic tomography in permafrost

Canadian Geotechnical Journal ◽

10.1139/t04-026 ◽

2004 ◽

Vol 41 (5) ◽

pp. 796-813 ◽

Cited By ~ 19

Author(s):

Anne-Marie LeBlanc ◽

Richard Fortier ◽

Michel Allard ◽

Calin Cosma ◽

Sylvie Buteau

Keyword(s):

Seismic Tomography ◽

Dynamic Properties ◽

Cone Penetration Test ◽

The Body ◽

Body Waves ◽

Reconstruction Technique ◽

Seismic Velocities ◽

Penetration Test ◽

Cone Penetration ◽

Seismic Cone Penetration Test

Two high-resolution multi-offset vertical seismic profile (VSP) surveys were carried out in a permafrost mound near Umiujaq in northern Quebec, Canada, while performing seismic cone penetration tests (SCPT) to study the cryostratigraphy and assess the body waves velocities and the dynamic properties of warm permafrost. Penetrometer-mounted triaxial accelerometers were used as the VSP receivers, and a swept impact seismic technique (SIST) source generating both compressional and shear waves was moved near the surface following a cross configuration of 40 seismic shot-point locations surrounding each of the two SCPTs. The inversion of travel times based on a simultaneous iterative reconstruction technique (SIRT) provided tomographic images of the distribution of seismic velocities in permafrost. The Young's and shear moduli at low strains were then calculated from the seismic velocities and the permafrost density measured on core samples. The combination of multi-offset VSP survey, SCPT, SIST, and SIRT for tomographic imaging led to new insights in the dynamic properties of permafrost at temperatures close to 0 °C. The P- and S-wave velocities in permafrost vary from 2400 to 3200 m/s and from 900 to 1750 m/s, respectively, for a temperature range between 0.2 and 2.0 °C. The Young's modulus varies from 2.15 to 13.65 GPa, and the shear modulus varies from 1.00 to 4.75 GPa over the same range of temperature.Key words: permafrost, seismic cone penetration test, vertical seismic profiling, seismic tomography, dynamic properties.

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