Bayesian approach for probabilistic characterization of sand friction angles

Bayesian model comparison and selection of spatial correlation functions for soil parameters

As a joint research project sponsored by the French–Norwegian Foundation for Scientific and Industrial Research, the Norwegian Geotechnical Institute, Geodia/Geocean, and École Polytechnique have carried out in the summer of 1990 a series of special in situ pressuremeter and cone penetration tests at a permafrost site in Longyearbyen, Svalbard. The purpose of the testing program was to compare the results of the two different field testing methods and to check the potential of such methods for serving as a basis for prediction of the behaviour of foundations in permafrost. As pressuremeter test results have been presented in a previous publication, this paper shows only the results of cone penetration tests and their interpretation in terms of strength and creep parameters of the frozen soil. Subsequently, the same data are used to predict the behaviour under long-term axial load of two prefabricated and one cast-in-place concrete pile that were tested by the Selmer Furuholmen Anlegg A.S. in cooperation with the Norwegian Geotechnical Institute at the same site for 3 years. Key words : permafrost, cone penetration tests, piles field loading tests, creep settlement.

Friction angle and overconsolidation ratio of soft clays from cone penetration test

Quantification of prior knowledge in geotechnical site characterization

The present paper responds to the challenge of modeling uncertainty in soil strength parameters concerning its spatial variability in a situation of limited soil information. Understanding this uncertainty allows for the management of the risk of geotechnical structure failure. In the present work, this uncertainty is identified based on signals from the cone penetration test (CPT) device. Signals are directly transformed using existing interpretation methods (typically used as a source of mean values of parameters for a given range of depths) to obtain depth-varying effective strength parameters of the soil. The process is performed by incorporating data from two case studies from different locations in similar soil materials. First, Keswick clay from Australia, for which the results of both CPT and laboratory tests are available, is examined. Second, to further verify the obtained results, the soil from Poland called Świerzna clay, for which only CPT signals were available, is also tested. As shown, the variability of the transformed signals can be a good source of information for identifying uncertainty in soil strength. It agrees well with literature data and can be used to identify random fields describing soil parameters.

In case of major projects there are numerous measurements which provide a sufficient set of data to determine characteristic values based on statistical methods. In the current paper Cone Penetration Test (CPT), oedometer and Flat Dilatometer Test (DMT) results are analyzed. Constrained or oedometric modulus is one of the most important deformation parameters, which has a key role in settlement estimation. There are various recommendations to derive Eoed from CPT tip resistance values. Three of these recommendations are compared with the results of the oedometer tests and the correlation used in case of DMT measurements.

This paper presents the results of attempts to identify organic soils on the basis of test results performed under in situ conditions by cone penetration testing (CPT). The results of 439 selected tests were analysed which reflected the behaviour of local organic soils of organic matter ranging from 6,3 to 17,4%. Crucial to soil investigation were values measured of cone resistance (qc) and sleeve friction (fs) and the friction ratio (Rf) estimated according to those values. To identify organic soils, selected criteria were used, proposed among others by: Mayne, Marr, Bergmann, Schmertmann, Capanella and Robertson [2,5]. An analysis showed that an identification of organic soil types in terms of the present classification of standards, in view of the criteria used, is ambiguous and does not allow to identify them precisely by CPT.

Free fall penetrometers (FFP) can improve the efficiency of deepwater geotechnical site investigations. This study investigates the derivation of geotechnical properties from piezocone FFP measurements in the upper 4 m of the seabed at a clayey site with water depths of ∼1500 m. Data analysis methods as commonly applied in cone penetration test (CPT) analysis were tested with strain rate normalization methods previously suggested for FFP analysis. The logarithmic, inverse hyperbolic sine, and power law approaches were applied for strain rate normalization. Strain rate effects appeared small for FFP cone resistance (with μ = 0.1 for the logarithmic and β = 0.06 for the power law approach), but were apparent. Undrained shear strength derived from FFP data matched overall the CPT results, using an N factor Nkt = 12. Undrained shear strength derived from excess pore pressure measured at the u1 position also yielded favorable results using N∆u _FFP = 6. Two soil behavior type classifications showed acceptable agreement between strain rate normalized FFP and CPT results.

ABSTRACTThe need for effective and reliable methods to survey and monitor the structure of earth‐fill dams recently became pressing in light of the increasing number of flood events in central Europe. Among geophysical techniques, dam imaging using electrical resistivity methods is applied in most cases. Occasionally, ground‐penetrating radar is applied in the framework of the search for subsurface facilities. Seismic methods are rarely used.This paper focuses on the multichannel analysis of the surface waves (MASW) method to determine dynamic soil properties and aims to extend its application field to dyke and dam structures. The standard processing procedure of the MASW assumes a flat free surface of infinite extension. The flat surfaces of a dyke, in contrast, are in the order of 1–10 times smaller than the wavelengths in the soil; disturbing side reflections will occur. Even though MASW has already been applied on a few dyke sites, the effect of such an obvious breach of preconditions needs to be studied before the method can be recommended.In this paper the influences of the dyke’s topography on the test results are studied by means of a numerical analysis. Typical cross‐sections are modelled using 2.5D finite and boundary elements. The results of models taking the topography into account are compared with models neglecting the topography. The differences are evaluated on the level of the dispersion curves and for one cross‐section on the level of the S‐wave velocity. They were found to be insignificant for dykes with a width‐to‐height ratio larger than four.A testing campaign was conducted providing the chance to collect experience in the practical use of the MASW method on dykes. Test results obtained at two test sites are selected and compared to the results of borehole logs and cone penetration tests. A remarkable relation between the S‐wave velocity and the consistency of the clay sealing was found at one site; a distinct positive correlation to the measured cone tip resistances was achieved on the other test site. Valuable information on the composition of the dyke body and base could be obtained but the resolution of the method to identify small areas of inhomogeneity should not be overestimated.

Intensive economic development is associated with an increasing demand for raw materials, including minerals. An illustrative example of this issue is the development of the copper industry. A significant problem arising from the scale of copper production is the management of an ever-growing amount of post-flotation tailings. This necessitates the need to ensure the continuity of safe storage. This study presents the results of studies on the behavior of deposits in the Żelazny Most Tailings Storage Facility (Poland). The primary objective of this study was to estimate the settlements of tailings under variable deposition conditions. The results were assessed using two methods: indirect and direct; this was based on cone penetration test (CPTU) results. The results were verified using Modified Cam Clay (MCC) modeling. Depending on the type of test, settlements ranged from several dozen centimeters to over three meters. Despite the observed differences, the results of both CPTU methods indicate a convergent trend in tailings behavior. Conversely, the results estimated using the direct method and numerical modeling demonstrate a high level of agreement.

Cone penetration in mixed or intermediate soils (soils containing mixtures of sand, silt and clay) is neither fully drained nor fully undrained at the standard cone penetration rate of 20 mm/s. Considerable research, mainly relying on centrifuge tests, has been undertaken to quantify the effects of penetration rate (and thus partial drainage) on cone resistance. In this paper, the effects of penetration rate on cone resistance in saturated clayey soils were investigated by performing field tests and miniature cone penetration tests in a calibration chamber. The field tests were performed at sites especially selected to span the range of drainage conditions from fully drained to fully undrained. The calibration chamber tests, using both conical and flat-tip penetrometers, were performed at different penetration rates in two specimens prepared by mixing kaolin clay and sand with different mixing ratios and one-dimensionally consolidateding the mixtures. A correlation between cone resistance and drainage conditions is established based on the cone penetration test results. The transitions from no drainage to partial drainage and from partial drainage to full drainage are defined as a function of penetration rate normalized with respect to the penetrometer diameter and the coefficient of consolidation.

Physical modeling of cone penetration testing (CPT) can be carried out under known stress, deformation, and density conditions using laboratory calibration chambers. This study presents the results of reduced-scale model CPTs (MCPT) on Fraser River sand using a calibration chamber that allows anisotropic consolidation of soil specimens, as well as the measurement of shear wave velocity (VS), using bender elements. In addition to VS, MCPT can also measure cone tip resistance (qc), sleeve friction (fs), and pore water pressure developed behind the cone tip (Δu2). The CPT model tests are performed on Fraser River sand at different effective stresses and relative densities. The CPT calibration chamber test results are comparable with those of in situ seismic cone penetration tests (SCPT) in the Fraser River delta, existing correlations between VSand qc, and calibration chamber tests on other sands. This confirms the overall feasibility of the MCPT calibration chamber design for the measurements of qc, fs, and VSin sandy soils.

The cone loading tests (CLT/CLT-u) represent an innovative alternative to the conventional CPT test, allowing the measurement of soil stiffness. This paper aims to present the results of an experimental study of the (CLT/CLT-u) within the framework of physical modeling at natural gravity by using the calibration chamber. This technique makes it possible to carry out a full-scale penetration test within a soil slice. After describing the experimental devices and the loading program, the paper will focus on the presentation and discussion of the results of cone penetration (CPT) and cone loading (CLT) tests in Fontainebleau sand and Speswhite Kaolinite clay. Experimental load-transfer curves were then derived, and their parameters were determined. It was found that the cone modulus and the friction stiffness linearly increase with depth, according to the model of Gibson’s soils. Comparison with the conventional soil properties of the soils tested led to the conclusion that these parameters may be used for a practical characterization of the soil stiffness. Keywords: Cone loading test, Sand, Clay, Calibration chamber, Penetration, Stiffness

Summary This abstract presents a method for automated, stress-normalized stratigraphic classification of cone penetration test (CPT) data. The approach addresses key limitations in current practice, including manual interpretation, inconsistent layering, and lack of integration with geotechnical design models. The method uses friction ratio and stress-normalized cone resistance (referenced at 100 kPa effective stress) as primary classification parameters, defined through an engineer-controlled configuration file. Stress normalization is performed using a formulation inspired by the Hardening Soil model, allowing direct linkage between CPT-derived materials and stiffness-moduli used in numerical design. The method was applied to six CPTs from the Wilhelmshaven site in northern Germany, representing varied subsurface conditions. Each CPT was processed through a two-pass normalization and classification loop, with a minimum layer thickness constraint of 0.3m to reduce interpretive noise. Outputs include model materials with geotechnical properties and layer boundaries, suitable for integration into 2D/3D modelling workflows. Results demonstrated consistency across CPTs, preserved thin but interpretable layers, and highlighted site variability via 3D visualization. The method enables transparent, reproducible ground modelling from raw CPT data and improves the connection between site characterization and design-stage geotechnical modelling. Future extensions will focus on uncertainty quantification and full 3D model generation.

This contribution examines the applicability of ordinary kriging to interpolate the results of cone penetration tests or CPTs. The advantages of geostatistics are studied for two datasets of CPTs measured in a typical soil encountered in Flanders, Belgium: the Boom clay. Firstly the unit pile base resistance of a pile with a diameter of 0.4 m is studied, for a specific depth separately. Secondly the characteristic resistance of an axially loaded pile is considered. In that part of the study the whole profile is estimated at once, instead of estimating the value at a specific depth. From the study one can conclude that it is possible to estimate the bearing capacity accurately in a point if sufficient measurements are carried out in the immediacy of that point and that ordinary kriging can be a good method to make an estimation of the characteristic resistance of an axially loaded pile.