Search Results (29)

The technique of static or dynamic probing is the most commonly used research method for characterizing soil media under in situ conditions. It allows engineers and geotechnical specialists to gain crucial insights into the soil properties, which are essential for designing foundations and other structural elements. One of the newest devices, the Panda variable energy dynamic penetrometer, has gained popularity due to its versatility and ease of use. It is widely used in Western European countries, especially in France, but remains practically unknown in Poland, where traditional methods as static and dynamic probe tests still dominate. The article presents a comprehensive analysis of field test results, including static cone penetrometer CPTu, lightweight dynamic penetrometer DPL, and the PANDA dynamic penetrometer. The aim of these tests was to evaluate the effectiveness of the Panda cone penetrometer by comparing the obtained results with those from the CPTu and the DPL. Correlational relationships obtained between the static (q_c) and dynamic (q_d) penetration resistance of the CPTu, DPL and Panda probes are presented. Full article

Bentonite materials are extensively used in cutoff walls at landfill sites. This study calculates the stress and permeability characteristics of bentonite materials using the piezocone penetration test (CPTU) and ABAQUS simulations. The lateral effective stress of bentonite materials is evaluated using arching models, lateral squeezing models, and a modified lateral squeezing model. Pore pressure dissipation types are categorized into standard and non-standard, with the coefficient of consolidation obtained using the half dissipation time of excess pore pressure (t₅₀) method. In the standard dissipation type, the excess pore pressure gradually dissipates over time after the cone stops penetrating. In contrast, the non-standard dissipation type is characterized by an initial increase in pore pressure until it reaches a maximum value, followed by a decrease to hydrostatic pressure. Additionally, the pore pressure dissipation process in bentonite cutoff walls is recorded and analyzed over various time intervals. Finally, the relationship between hydraulic conductivity and t₅₀ at landfill sites is established based on standard and non-standard dissipation types using CPTU and ABAQUS methods. The t₅₀ method is used for the standard dissipation type, while a modified t_50m method is used for the non-standard dissipation type from CPTU and a t_50m method is used in the non-standard dissipation type from CPTU. The t_50m is the modified value derived from t₅₀. Cutoff walls made from bentonite materials offer the advantage of enhancing the isolation effects and meeting the design requirement of permeability (1.0 × 10⁻⁷ cm/s). Full article

Soil void ratio is a key parameter in geotechnical engineering design and geological hazard prevention. However, existing methods for determining void ratio are plagued by issues such as difficulty in sampling, susceptibility of samples to disturbance, and heavy experimental workload. The cone penetration test, with its advantages of simple operation, high survey efficiency, and high accuracy, has gradually become a commonly used in situ testing method in engineering investigations. Based on data from the Yellow River Delta, this paper evaluates the applicability of several models related to void ratio. Combined with the Robertson density prediction model, a semi-empirical model for predicting void ratio based on the piezocone penetration test (CPTu), in situ testing is proposed, which enables efficient evaluation by establishing a conversion mechanism between soil density and void ratio. Verification using a database built from six types of nearly saturated sedimentary soil data shows that underestimation of predicted density will amplify the error of soil void ratio. The prediction accuracy is significantly improved after coefficient correction. Finally, a simple model for predicting void ratio that only requires CPTu data is developed, providing a sampling-free evaluation tool for estuarine and marine sedimentary areas. Full article

This study introduces a novel method for evaluating pile–soil interaction based solely on Dilatometer Test (DMT) results, enhancing and extending the established approach originally developed using Menard Pressuremeter Test (PMT) data. Currently, transfer functions utilizing DMT sounding results are in the early stages of development. Presented research fills the gap in DMT-based methods for pile design by introducing transfer functions for reversal loadings to calculate the unit shaft friction of screw displacement piles in Controlled Modulus Columns (CMC) technology. The proposed method utilizes DMT-derived soil parameters, offering a practical and accurate alternative to PMT-based models. Testing research fields were located in the Vistula Marshlands, Northern Poland. Site characterization consisted of piezocone (CPTU) and DMT soundings to characterize the soil profile and estimate soil parameters relevant for pile design. CMCs were installed and statically load tested under various loading schemes. Laboratory direct shear tests on smooth and rough soil-concrete interfaces were performed in both forward and backward directions (reversal loading) to simulate pile loading conditions. Results demonstrate improved adaptability of DMT-based transfer curves to local soil conditions and provide a reliable framework for predicting pile performance in soft soils. Proposed DMT-model returns similar ultimate bearing capacities of the pile to CPT 2012 method for first loading, simultaneously offering better agreement for reversal loading, a situation not accounted for in CPTU 2012 or most other CPT-based methods. Full article

Cone Penetration Tests with pore pressure measurements (CPTu) are widely used in geotechnical site investigations due to their high-resolution profiling capabilities. However, traditional interpretation methods—such as the Soil Behavior Type Index ($I_c$)—often fail to capture the internal heterogeneity typical of mining tailings deposits. This study presents a machine learning-based approach to enhance stratigraphic interpretation from CPTu data. Four unsupervised clustering algorithms—k-means, DBSCAN, MeanShift, and Affinity Propagation—were evaluated using a dataset of 12 CPTu soundings collected over a 19-year period from an iron tailings dam in Brazil. Clustering performance was assessed through visual inspection, stratigraphic consistency, and comparison with $I_c$-based profiles. k-means and MeanShift produced the most consistent stratigraphic segmentation, clearly delineating depositional layers, consolidated zones, and transitions linked to dam raising. In contrast, DBSCAN and Affinity Propagation either over-fragmented or failed to identify meaningful structures. The results demonstrate that clustering methods can reveal behavioral trends not detected by $I_c$ alone, offering a complementary perspective for understanding depositional and mechanical evolution in tailings. Integrating clustering outputs with conventional geotechnical indices improves the interpretability of CPTu profiles, supporting more informed geomechanical modeling, dam monitoring, and design. The approach provides a replicable methodology for data-rich environments with high spatial and temporal variability. Full article

Evaluation of soil properties in highway design is an important but time-consuming task that does not always provide the necessary information to detect issues associated with changes in soil properties along the road project. California Bearing Ratio (CBR) tests are commonly used to identify soil properties and as an input in pavement design; however, it could be considered a slow test and, therefore, not always performed to the extent that it may be desired on the field. A comparison between CPT and CBR is performed in this work to obtain a correlation between them to be used in design. The effects of moisture content are also investigated in CPT and CBR to determine which conditions should be tested to obtain representative or design conditions for the pavement. A good correlation is found between CPT tip resistance and in situ CBR. It is observed that CBR and cone tip resistance change significantly for moisture contents up to 30 to 40%. It was found that tip resistance should be evaluated at a depth of 20 cm inside the subgrade to estimate adequate CBR values. Full article

With the development of the offshore wind industry in China, the amount of offshore wind turbines has increased rapidly. Large-diameter steel monopile foundations of offshore wind turbines have been widely adopted in China with lots of marine clay located. However, the conventional offshore wind monopile bearing capacity prediction from the American Petroleum Institute (API) based on the small-diameter flexible pile field test is inaccurate with the rigid mechanism of large-diameter monopile causing economically loss. The piezocone penetration test (CPTU) is a common marine in situ test to exactly acquire soil parameters. Therefore, a CPTU-based offshore wind monopile rigid mechanism inference method is proposed. A creative numerical offshore wind power monopile and CPTU combined model is established through COMSOL. A self-compiling parameter function is applied to soil modeling and an innovative mobile boundary function is created to simulate CPTU penetration. Through the model, real-time CPTU data can be acquired when monopile is applied with different horizontal loads. The peripile soil stress change can be timely detected by CPTU. Through CPTU data, the monopile rigid bearing mechanism is verified. A rigid rotation center is found at the 60% point of the inserted monopile. The method is an important foundation for the next step of monopile bearing capacity research. Full article

The disturbance generated during the pile installation process increased the compressibility of the soil between the piles, thereby causing additional settlement of the composite foundation. This study was conducted against the background of a highway soft foundation treatment project in Zhongshan. Before and after the installation of cement mixing piles (CMP) and pre-stressed high-strength concrete pipe pile (PHC), a piezocone penetration test (CPTU) was applied to assess the soil between the piles and quantify the disturbance. Based on this, the settlement of the composite foundation was predicted using the stress modified method and finite element method (FEM). The results indicate that under low embankment load (<2.5 m), the installation of PHC piles reduces the compression modulus of the soil between the piles by approximately 30%, while CMP results in a reduction of about 10%. Disturbance settlement from CMP and PHC piles accounts for approximately 3–10% and 17–28% of the total settlement, respectively. This impact diminishes with the increase of embankment load. Full article

This work presents an analysis of the relationship between strength parameters determined in the laboratory and the results of a cone penetration test with pore water pressure measurement (CPTU) of waste soils in the “White Seas” area in Cracow. Anthropogenic soil is an alkaline waste formed during the production of soda ash and deposited in the area of the former Solvay Sodium Plant factory in Cracow, Poland. Due to the large area of the land and numerous investment plans and completed buildings, there was a need to identify reliable functional relationships enabling the determination of the strength parameters of these soils based on the results of the CPTU. Statistical analysis showed that the best correlation with the test results was provided by two logarithmic functions in which the dependent variables were the effective friction angle and effective cohesion. The dependent variable for both cases was the corrected cone resistance q_t. The functional relationship combined data from labour-intensive, long-lasting and costly laboratory measurements with quick and less expensive measurements, i.e., in situ CPTUs. The obtained relationships enable the determination of the strength properties of the subsoil of these anthropogenic soils. Full article

This study employs Cone Penetration Tests (CPTu) and Standard Penetration Tests (SPT) to analyze the geotechnical properties of the Magdalena River’s riverbed and banks. While these methods are standard in soil characterization, this research innovatively combines CPTu’s continuous profiling with SPT’s localized sampling to develop a nuanced stratigraphic model of the subsurface. This integrated approach provides a comprehensive view of the soil conditions, which is crucial for understanding sediment variability and stability along the riverbanks. The findings from this methodological integration enhance our ability to predict soil behavior under dynamic riverine conditions, offering valuable insights for erosion control and sustainable river management. The study underscores the practical benefits of synergizing traditional testing methods to address geotechnical challenges in river environments. Full article

Clarity in monitoring existing foundation structures demands innovative safety analysis methodologies for deep foundations, necessitating advanced models calibrated with real-world field parameters. Understanding controlled conditions, including geotechnical profiles, seismic attributes, and soil mechanics, is crucial. A dedicated research group at the University of São Paulo spent three years refining these conditions, characterizing an experimental field along a canal in São Paulo. This study pioneers geotechnical and geomechanical characterization of the region’s tertiary sediments in São Paulo, offering valuable insights for current and future applications. Standard penetration tests with torque (SPT-Torque), piezocone tests (CPTu), and measurement of wave velocity (Vs) with piezocone tests (S-CPTu) were carried out. The exploration of the subsoil shows that in up to 2 m of excavation, there are clays and silts, and in up to 25 m, there is a significant layer of compact fine sand that has high values of tip resistance and wave velocities more significant than 100 m/s. In the electric cone tests, the abacus used displayed a reasonable classification. All propositions identified the transition from the surface soil to the sandy soil at between 3 and 25 m. The soil classification values were obtained with the data of the field parameters, and the geotechnical and mechanical parameters were estimated. No differences were detected among the values found in the SPT-T and CPTu tests for the values obtained via cone resistance. This demonstrates the reliability of both methods. In addition, using the CPTu test to identify the stratigraphic profile horizons employing the soil’s mechanical behavior when the cone is driven proved appropriate. Full article

The undrained shear strength is an essential parameter in the foundation design of marine structures. Due to the complex marine environment and technical limitations, it is difficult and costly to obtain offshore samples. Piezocone penetration tests (CPTU) are relatively low-cost compared to drilling and sampling methods. Therefore, based on the soil behavior type index (I_c) derived from CPTU results, a model for estimating cone factors (N_kt, N_ke) is proposed to improve the accuracy of estimation of undrained shear strength. The result shows that the soil behavior type index (I_c) and cone factors take on a negatively correlated exponential relation. Incorporating a cone factor that varies with the soil behavior type index (I_c) significantly enhances the accuracy of undrained shear strength predictions compared to the conventional method of using a constant cone factor. This approach reduces the root mean square error (RMSE) for N_kt (N_ke) from 0.124 (0.126) MPa to 0.056 (0.06) MPa, and the mean absolute error (MAE) from 0.0154 (0.016) MPa to 0.0032 (0.0036) MPa. The method was validated at an additional location and the predictions were in high agreement with the results of the consolidated quick direct shear test. The developed method can serve as an effective tool used in the design of foundations of marine structures. Full article

The paper demonstrates how the concepts presented in the companion paper: “Determination of Constrained Modulus of Granular Soil from In Situ Tests—Part 1 Analyses” can be applied in practice. A settlement design based on the tangent modulus method is described. Extensive in situ tests were performed on a well-documented test site consisting of sand with silt and clay layers. The field tests comprised different types of penetration tests, such as the cone penetration test, the flat dilatometer, and the seismic down-hole test. The modulus number and the constrained tangent modulus were derived from the cone penetration test with pore water pressure measurement and the flat dilatometer test. In addition, the shear wave speed was determined from two seismic down-hole tests, from which the small-strain shear modulus could be evaluated. The constrained modulus obtained from the cone penetration test with pore water pressure measurement (CPTU) and the flat dilatometer (DMT) was compared with that from the seismic down-hole tests. The importance of the stress history on the constrained modulus was demonstrated. The range of modulus numbers, derived from different in situ tests, compares favorably with empirical values reported in the literature. Full article

The increasing occurrence of landslides worldwide causes many human casualties and huge socio-economic losses. Therefore, the fastest and most accurate characterisation of landslides is important. The objective of this study is to compare how well the flat dilatometer (DMT) test and the piezocone penetration (CPTU) test can find the depth of a sliding zone. Inclinometers were used to measure horizontal changes in the soil to ensure the depth of the sliding zone was correct. The coincidence of the results of in situ static probes, and the displacements of the inclinometers is a sure confirmation of the depth of the sliding zone. In the example of Bedekovčina and Kravarsko landslides, in situ static probes were used to obtain values of input parameters on the sliding zone for parametric sensitivity analysis of parameters. Sensitivity analysis was performed by plotting the relationship between the above parameters and the vertical effective stress σ′_vo on the sliding zone. The sensitivity analysis of the parameters of 11 tested samples shows that for the parameters of the obtained DMT probe, a higher sensitivity of the parameters is obtained, closer to the values concerning the expected range, and a minor standard deviation. The parameter K_d obtained by dilatometer probing is the best indicator of the depth of the sliding zone. The literature value K_d = 1.8–2.0 on the sliding zone in this paper is extended to the range K_d = 1.8–2.5, and its detection sensitivity is influenced by over-consolidation in shallow soil layers. In general, the research results show that the dilatometer probe has an advantage over the piezocone penetrometer test for the needs of landslide characterisation. Full article

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. Full article