Cone Penetration Test In Sands Research Articles

Revisiting interpretation of relative density from shallow depth CPTs in sand

The relative density is an important state parameter in the determination of engineering properties of marine sands. Existing industry-acknowledged cone penetration test (CPT) correlations to relative density have been developed almost exclusively from the results of calibration chamber testing performed at stress levels higher than 50 kPa. A few studies suggest correlations for low stress levels as well, however, mainly for unaged normally consolidated soils. Existing formulations are often found to be challenged in the application for dense to very dense aged overconsolidated marine sands. This paper investigates the conditions and response of overconsolidated medium dense to very dense sand (as typically found in the North Sea) at shallow depths (less than 50 kPa) for a penetrating cone. It provides recommendations for a consistent set of parameters linking CPT parameters to the stress conditions, expressed by the apparent overconsolidation ratio and coefficient of earth pressure at rest, and the relative density. The recommendations are based on a comprehensive field-testing campaign at a sand site in Cuxhaven, Germany, supported by a suite of laboratory testing and numerical analyses.

Numerical investigation on evolving failure of caisson foundation in sand using the combined Lagrangian-SPH method

ABSTRACTCaisson foundations are often used in offshore engineering. However, for an optimum design understanding the failure process of a caisson during its installation and the subsequent external loadings is crucial. This paper focuses on the evolving failure of a caisson foundation in sand by advanced numerical modeling. A combined Lagrangian-smoothed particle hydrodynamics method is adopted to deal with the large deformation analysis. The method with parameters are first calibrated and validated by a simulation of cone penetration test in sand. The results of an experimental campaign of a caisson in the same sand are selected and validated for the numerical model. Then, more representative loading combinations are designated for numerical modeling of failure process and mode. Furthermore, three additional caisson dimensions D/d = 0.5, 1.5, and 2.0 (changing the ratio of caisson diameter D to skirt length d while keeping the same soil-structure surface contact area) are simulated under six representative combined loading paths. Based on that, the influence of caisson dimension to the failure process and mode is investigated. All results are helpful to estimate all possible sliding surfaces under different monotonic combined loading paths for further limit analysis.

In situ horizontal stress from CPT in sand: a new approach

Despite the various approaches in the literature adopted for analysing cone penetration test (CPT), determination of the initial horizontal stress and relative density of a sandy soil during this test has not been tackled yet. In order to propose a new method in this regard, a numerical study of CPT has been performed and the predicted results have been compared with several databases of comprehensive calibration chamber tests. The penetration mechanism has been then fully investigated by presenting different kinds of outputs for the surrounding soil. Finally, an innovative procedure has been suggested for estimating the initial horizontal stress and relative density during performing CPT in a sandy soil. The suggested method is based on recording the time of occurrence of a pre-specified displacement in the surrounding soil during the test. This recording can be carried out using high-precision digital inclinometer systems which are mounted in some boreholes in different directions and various distances around the location of CPT.

Enhancing the CPT correlation with the small strain shear stiffness of sands

Abstract The cone penetration test (CPT) is a valuable geotechnical insitu test. Yet, the CPT correlations with the small strain shear modulus and seismic shear wave velocity still need more research to enhance their accuracy. In this study, the stress normalizations for the net cone tip resistance and the small strain shear modulus are scrutinized. Subsequently, enhanced CPT correlations with the small strain shear modulus and the seismic shear wave velocity for sands are presented. The proposed approach utilizes published databases of CPT in sands and recent researches that quantify the small strain shear modulus using sand gradation parameters. Four case histories are analyzed using the suggested correlation and the results confirm that the presented approach is a promising enhancement to the CPT correlations with the small strain shear modulus and seismic shear wave velocity in sands.

Centrifuge cone penetration tests in sand

When performing centrifuge tests, it is necessary to carry out in-flight tests such as the cone penetration test (CPT). Recently, miniature CPTs have formed one collaboration entitled 'European Pro ...

Development of an Axisymmetric Field Simulator for Cone Penetration Tests in Sand

Abstract An experimental system capable of simulating axisymmetric field conditions has been developed. This system, as an improvement over conventional calibration chambers, enables cone penetration tests (CPT) to be calibrated under minimal boundary effects. The new simulator consists of a stack of 20 rings to house the sand specimen. These rings are lined with an inflatable silicone rubber membrane on the inside. The boundary expansion and stress are measured and individually controlled, respectively, at each ring level during the CPT. The soil from physical boundary to infinity is simulated using a nonlinear cavity expansion curve derived from a lateral compression test on the specimen. Results from a series of CPTs show that at relative densities of approximately 80%, the cone tip resistance values agree within 4% as the diameter ratio of the physical specimen over cone varies from 18 to 22. This paper describes unique features of this field simulator, presents available CPT data performed in the simulator, and discusses its implications on future calibration tests.

Theoretical analysis of the cone penetration test in sands : De Simone, P; Golia, G Proc 1st International Symposium on Penetration Testing, ISOPT-1, Orlando,20–24 March 1988V2, P729–735. Publ Rotterdam: A A Balkema, 1988

Theoretical analysis of the cone penetration test in sands : De Simone, P; Golia, G Proc 1st International Symposium on Penetration Testing, ISOPT-1, Orlando,20–24 March 1988V2, P729–735. Publ Rotterdam: A A Balkema, 1988

Cone penetration test calibration for Erksak (Beaufort Sea) sand

Interpretation of the cone penetration test in sands is generally based on empirical calibrations from tests in large-diameter calibration chambers. Although interpretation of these calibration data for clean sands in terms of the state parameter is expected to be broadly applicable to other sands, material-specific correlations are desirable for many projects. This paper describes a series of calibration chamber tests carried out on a sand dredged from the Beaufort Sea for construction of artificial islands. This Erksak sand is a uniformly graded, subrounded medium-grained sand with a fines content of 3–6%. The testing chamber described is 1.4 m in diameter, and allows independent control of vertical, horizontal, and back pressures on the sand sample. Samples of the sand were prepared by moist compaction to preserve the fines content, and then back pressure saturated.The chamber test data are presented and confirm that the Erksak sand fits the general trends observed for other sands very well. A method is also described that allows the interpretation to be consistent, even in the event that nonuniform void ratios occur in the samples. Measurements of horizontal stress behind the cone tip, which is a new development in cone penetrometer testing, are also presented. Key words: cone penetrometer, sands, in situ tests, state, calibration chamber, horizontal stress measurement.

The cone penetration test in sands: part II, general inference of state

The state parameter concept provides a new method of characterizing sand behaviour, but the utility of the concept relies on the ability to measure the state parameter in situ. Part I of this Paper demonstrated a relationship between normalized cone resistance and state parameter for Monterey sand. In this Paper the state parameter approach is applied to data from calibration chamber tests on several sands. It is shown that this approach leads to a common relationship for all the data that includes the effects of material type, quantified by the slope of the steady state line. The state parameter for a sand can therefore be determined in situ with a reasonable precision using a general framework of interpretation which applies to all uncemented sands. La notion de paramètre d'état fournit une nouvelle méthode pour caractériser le comportement des sables, mais son utilité dépend de la possibilité de mesurer le paramètre d'état in situ. La première partie de cet article démontre une relation entre la résistance au cône normalisée et le paramètre d'état pour le sable de Monterey. Cet article décrit l'application du paramètre d'état à des données obtenues à partir d'essais de chambres d'étalonnage effectués sur plusieurs sables. On indique que cette méthode conduit à une relation générale pour toutes les données qui comprend les effets matériels, quantifiés par la pente de la ligne d'état stationnaire. Par conséquent il est possible de dé terminer le paramètre d'état pour un sable en place avec une précision acceptable, en employant un cadre d'interprétation general qui s'applique à tout sable non-cimenté.