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1

The Use of CPTU and DMT Methods to Determine Soil Deformation Moduli—Perspectives and Limitations

Młynarek Z., Wierzbicki J., Lunne T.

Studia Geotechnica et Mechanica

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2023

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Vol. 45, nr s1

304--332

EN

The article presents the concept of determining constrained modulus—M0, initial shear modulus—G0, Young modulus—E, and rigidity index—IR on the basis of parameters from static penetration tests CPTU (Piezocone Penetration Testing), SCPTU (Seismic Piezocone Penetration Testing) and dilatometer tests DMT (Flat Dilatometer Test), SDMT (Seismic Flat Dilatometer Test). The basis for constructing the empirical relationships between the mentioned modules and parameters from the CPTU and DMT studies was to determine the factors that affect these relationships. The article discusses the impact of the following factors; geological and geotechnical conditions, conditions of recording measurements in CPTU and DMT tests, factors relating to the CPTU and DMT testing methods, factors affecting reference parameters from laboratory tests, factors related to subsoil properties. The basis for obtaining the empirical relationships for determining the analyzed modules and rigidity index were extensive research of the soils of various origins, in Poland. Measurement uncertainties and factors influencing the recorded parameters in the CPTU study were documented by the studies of the Norwegian Geotechnical Institute and the former Department of Geotechnics of the Agricultural University in Poznań. In these studies, penetrometers from several reputable manufacturers were used. The article summarizes the established empirical relationships for individual modules, taking into account the effect of over consolidation. It also comments on the interrelationship between constrained modulus M0 from CPTU and DMT test for soils in Poland.

2

Experience with CPTU, T-bar and ball penetrometers in two soft clays.

Lunne T.

Studia Geotechnica et Mechanica

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2007

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Vol. 29, nr 1-2

87-101

EN

Field developments in deep waters with very soft soils have led to increased reliance on the use of in situ tests to evaluate soil design parameters. Recently the T-bar and ball penetrometers have been introduced due to their potential for increasing the reliability of interpreted undrained shear strength relative to the CPTU for soft clays. Empirical correlations based on field tests and laboratory tests on samples at two onshore soft clay sites indicate that T-bar correlation factors are in a somewhat narrower range compared to cone factors. Recommendations are given in terms of cone and T-bar factors to use.

3

Use of CPTU data in clays/fine grained soils

Powell J. J.M., Lunne T.

Studia Geotechnica et Mechanica

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2005

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Vol. 27, nr 3-4

29-65

EN

The Piezocone test (CPTU) continues to gain in popularity as a result of its potential, particularly in clay soils. In order to have confidence in the interpretation of CPTU results in clay soils, it is vital that the test results are accurate and representative of the in situ soil conditions. This can be achieved by using equipment and procedures following the new International Reference Test Procedure (IRTP) (and in future the forthcoming ISO document on CPTU). A particular feature of the IRTP is the introduction of Accuracy Classes according to what the results are to be used for. This aspect is discussed in some detail. Testing on land is normally done by pushing from ground level until refusal or to a predetermined depth. A new and very interesting method whereby CPT’s can be carried out while drilling is advanced facilitates continuous testing to large depths. The rest of the paper covers the use of CPTU for engineering purposes in clays soils. The aspects that are dealt with are: layering and identification of soil type, stress history, lateral stress ratio, undrained and remoulded shear strength, small strain shear modulus, coefficient of consolidation and in situ pore pressure.

4

Identyfikacja jednorodności podłoża różnymi rodzajami penetrometrów w ujęciu analizy statystycznej

Młynarek Z., Kroll M., Wołyński W., Lunne T.

Inżynieria Morska i Geotechnika

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2003

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nr 3-4

139-144

PL

W artykule przedstawiono analizę zmienności parametrów statycznego sondowania na podstawie badań wykonanych na poletku doświadczalnym w Norwegii oraz ocenę istotności różnic między parametrami i różnic pomiędzy współczynnikami trendu dla oporu stożka, tarcia na tulei ciernej i ciśnienia wody w porach z głębokością.

EN

The paper presents variability analysis of parameters of the static penetration test carried out with nine penetrometers in an experimental field in Norway, and the evaluation of the significance of the differences between the parameters, assessment of the significance of differences between the trend coefficients for cone resistance, sleeve friction and pore pressure with depth.