Dynamic analysis of a smooth penetrometer free-falling into uniform clay

Nazem, Majidreza; Carter, John; Airey, David; Chow, Shiao Huey

doi:10.1680/geot.10.p.055

Cited by 63 publications

(32 citation statements)

References 28 publications

(27 reference statements)

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“…For cohesive sediments such as soft clays, either side friction along the rod needs to be taken into account, or the penetrometer needs to be designed (e.g., as full-flow penetrometer, or by the incorporation of friction reducers) to minimize friction at the interface between rod and soil (cf. Lunne et al 1997;Randolph 2004;Chung and Randolph 2004). At peak deceleration of 20 m/s 2 , the buoyancy of the rod immersed in the sediment amounts to approx.…”

Section: Processing Of Impact Penetrometer Datamentioning

confidence: 99%

“…Correction of cone resistance data Due to the mechanical design of the cone, the cone resistance measured by the instrumented tip of the impact penetrometer q dyn cone needs to be corrected for the unequal area effect (Lunne et al 1997) to obtain the corrected total cone resistance:…”

Section: Processing Of Impact Penetrometer Datamentioning

confidence: 99%

“…Typically, a reference velocity of 0.02 m/s is chosen to compare impact penetrometer data with static velocity CPT measurements. The soil viscosity coefficient has been applied for dynamic penetrations with penetrometers in clayey sediments, where it ranges between 0.04 and 1.50 (Dayal and Allen 1975;Dayal 1980;Randolph 2004;O'Loughlin et al 2004O'Loughlin et al , 2013Einav and Randolph 2005;Aubeny and Shi 2006;Low et al 2008;Zhou and Randolph 2009;Young et al 2011;Nazem et al 2012;Steiner et al 2012Steiner et al , 2014Airey 2013, 2014). Applications of the strain rate correction on silty sediments yield a soil viscosity coefficient between 0.13 and 0.36 (Perlow and Richards 1977;Biscontin and Pestana 2001).…”

Section: Processing Of Impact Penetrometer Datamentioning

confidence: 99%

“…Applications of the strain rate correction on silty sediments yield a soil viscosity coefficient between 0.13 and 0.36 (Perlow and Richards 1977;Biscontin and Pestana 2001). Several authors employing lightweight dynamic penetrometers penetrating sands at high rates have used values of 0.7-1.5 for the soil viscosity coefficient λ, although Dayal (1974), Dayal and Allen (1975), and Lunne et al (1997) concluded from laboratory observations that the strain rate correction is applicable only to cohesive sediments.…”

Section: Processing Of Impact Penetrometer Datamentioning

confidence: 99%

“…Measurements are taken in discrete intervals as a function of soil depth while maintaining a constant (static) penetration velocity. Correction and interpretation of these data are well assured by a broad theoretical (Baligh 1985;Teh 1987) and empirical background (see Lunne et al 1997 for review). Modern CPT instruments are equipped with strain gauges, and pore pressure is typically measured by means of pressure transducers.…”

Section: Introductionmentioning

confidence: 99%

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Validation of impact penetrometer data by cone penetration testing and shallow seismic data within the regional geology of the Southern North Sea

2015

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This study presents the assessment of total cone resistance from in situ deceleration measurements using the Lance Insertion Retardation meter (LIRmeter) in the Southern North Sea. The penetrometer is equipped with a measurement lance that is up to 6 m in length. The aim was to validate LIRmeter data interpretation within the regional geological context by comparison with static velocity cone penetration testing (CPT) and sub-bottom profiles. In total, 13 datasets were taken, in addition to preexisting hydroacoustical and static velocity CPT datasets. The dynamically acquired data were processed and compared to the reference static velocity data. The validation encourages the use of acceleration-based dynamic penetration tests, since a high degree of agreement was demonstrated between independently acquired dynamic and static cone resistance data. Moreover, the results reveal evidence of two successive formations with different geotechnical properties, consistent with existing knowledge on the regional setting. Additionally, there is novel indication of an incised glacial valley with muddy low-permeability sediments extending much further than reported to date, which would necessitate updating of older maps. The main advantage of penetrometer-based deceleration measurements lies in the robustness of the method, and the reliability of the sensors. However, penetration depth is, for dimensioning reasons, limited to the order of a few meters. Additionally, data processing includes the dependency of knowledge about the soil type to correct the dynamic data. These limitations can be satisfactorily outweighed by combination with reference data from static velocity tests, as demonstrated by integrating these data into a soil classification scheme.

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Section: Processing Of Impact Penetrometer Datamentioning

confidence: 99%

Section: Processing Of Impact Penetrometer Datamentioning

confidence: 99%

Section: Processing Of Impact Penetrometer Datamentioning

confidence: 99%

Section: Processing Of Impact Penetrometer Datamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Validation of impact penetrometer data by cone penetration testing and shallow seismic data within the regional geology of the Southern North Sea

2015

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On the calculation of cumulative strain around full‐flow penetrometers in steady‐state conditions

Osman

Randolph

2014

Num Anal Meth Geomechanics

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Summary An approximate solution for the effects of high strain rates, and gradual strength degradation, on the penetration resistance of penetrometers can be obtained by combining the strain‐path method with the classical upper bound theorem. The stream path calculations require the integration of the material constitutive equation along the streamlines. Unless the geometry is simple so that the integration can be evaluated analytically, numerical procedures are required to backtrack streamlines. The strain at any location is calculated by finding the streamline that passes through the given point and integrating the strain rate along that streamline from its inlet boundary. Thus, the calculations can be complicated, and errors can be accumulated during the calculation procedure. This paper presents an efficient approach for evaluating cumulative strains around penetrometers without the need to backtrack individual streamlines. In this approach, the strain components are treated as field variables. The global solution is obtained using the streamline upwind Petrov–Galerkin method. The new method together with an Eulerian‐based finite element formulation was used to study the cone penetration test and evaluate the effect of strain softening on the cone resistance. Copyright © 2014 John Wiley & Sons, Ltd.

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Frictionless contact formulation for dynamic analysis of nonlinear saturated porous media based on the mortar method

Sabetamal

Nazem

Sloan

et al. 2015

Num Anal Meth Geomechanics

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SummaryA finite element algorithm for frictionless contact problems in a two‐phase saturated porous medium, considering finite deformation and inertia effects, has been formulated and implemented in a finite element programme. The mechanical behaviour of the saturated porous medium is predicted using mixture theory, which models the dynamic advection of fluids through a fully saturated porous solid matrix. The resulting mixed formulation predicts all field variables including the solid displacement, pore fluid pressure and Darcy velocity of the pore fluid. The contact constraints arising from the requirement for continuity of the contact traction, as well as the fluid flow across the contact interface, are enforced using a penalty approach that is regularised with an augmented Lagrangian method. The contact formulation is based on a mortar segment‐to‐segment scheme that allows the interpolation functions of the contact elements to be of order N. The main thrust of this paper is therefore how to deal with contact interfaces in problems that involve both dynamics and consolidation and possibly large deformations of porous media. The numerical algorithm is first verified using several illustrative examples. This algorithm is then employed to solve a pipe‐seabed interaction problem, involving large deformations and dynamic effects, and the results of the analysis are also compared with those obtained using a node‐to‐segment contact algorithm. The results of this study indicate that the proposed method is able to solve the highly nonlinear problem of dynamic soil–structure interaction when coupled with pore water pressures and Darcy velocity. Copyright © 2015 John Wiley & Sons, Ltd.

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Dynamic analysis of a smooth penetrometer free-falling into uniform clay

Cited by 63 publications

References 28 publications

Validation of impact penetrometer data by cone penetration testing and shallow seismic data within the regional geology of the Southern North Sea

Validation of impact penetrometer data by cone penetration testing and shallow seismic data within the regional geology of the Southern North Sea

On the calculation of cumulative strain around full‐flow penetrometers in steady‐state conditions

Frictionless contact formulation for dynamic analysis of nonlinear saturated porous media based on the mortar method

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