"uuid","repository link","title","author","contributor","publication year","abstract","subject topic","language","publication type","publisher","isbn","issn","patent","patent status","bibliographic note","access restriction","embargo date","faculty","department","research group","programme","project","coordinates"
"uuid:9476b5cc-2a38-4861-ae2a-93c0942fd95e","http://resolver.tudelft.nl/uuid:9476b5cc-2a38-4861-ae2a-93c0942fd95e","Application of the Heat Flow Cone Penetration Test to measure the thermal conductivity of offshore soils","Vrielink, Leon (TU Delft Civil Engineering & Geosciences; TU Delft Geoscience and Engineering)","Vardon, P.J. (mentor); Daniilidis, Alexandros (graduation committee); Murali, M. (graduation committee); Delft University of Technology (degree granting institution)","2022","Interpretation of the thermal properties of soils is an important challenge in the field of geo-engineering, for example the development of geothermal energy solutions and for the design of electricity cable routes used for offshore wind farms. Of the thermal properties, the thermal conductivity is of most interest to find, as this determines the long-term thermal response of the soil. The soil volumetric heat capacity is of secondary interest, as this mainly influences the short-term thermal response.
To find the thermal properties of offshore soils, a new in-situ test is being developed, called the heat flow cone penetration test (HF-CPT). This test uses a module that can be attached to a cone penetration test (CPT) which contains a heating element and temperature sensors. In this test, the penetration trough the soil is stopped at a required depth, the heating element is then activated, and the thermal response of the probe is measured. This thesis presents an interpretation method that can predict the thermal conductivity of soils based on the thermal response of the HF-CPT. The interpretation method is validated by conducting laboratory tests in four different materials: moist sand, saturated sand, kaolin clay and a water-agar mixture. With the interpretation method, excellent results are found with the laboratory tests conducted in saturated sand, kaolin clay and the water-agar mixture.
The interpretation method is suitable for offshore testing, as the runtime of the method is short and the storage space is low. The interpretation method gives an accurate prediction for testing duration of about 300 seconds, which is fast when compared to other in-situ tests to measure the thermal conductivity of the soil. With this interpretation method, the HF-CPT can become a successful new in-situ test to determine the thermal conductivity of offshore soils. This way, the thesis contributes to the implementation of geothermal energy solutions and offshore cable routes for wind farms.
The objective of this thesis is to look at the spatial variability in the vertical direction of the Pleistocene sand from the Kreftenheye and Boxtel Formation in the Port of Rotterdam and see if the river Meuse has any influence on the spatial variability in the vertical direction. An additional question is asked if the spatial variability has any influence on the computation of the pile base capacity for a single foundation pile and what are the implications of the answer to that question. To answer these questions, four sites in the Maasvlakte, Botlek and Pernis were selected and the cone penetration tests (CPTs) taken at the twelve sites were used for this thesis. An empirical method which uses CPT data to identify soil layers was used to identify the Pleistocene sand layer in the CPT data. The first part of the thesis uses the cone resistance data of the CPTs to estimate the spatial variability of the sites. The second part of the thesis focuses on the additional research question by using random field theory. Per site, the mean, standard deviation and vertical scale of fluctuation θv were used to generate simulations of cone resistance data. For each combination of standard deviation and θv 500 simulations were carried out. For each simulation the pile base capacity was computed with two CPT-based averaging methods, Koppejan method and LCPC method. The coefficient of variation of pile base capacity is used to measure the uncertainty of the computed pile base capacity.
The results show that the range θv values are: 0.26 – 2 m in the Maasvlakte, 0.24 – 1.76 m in the Botlek and 0.14 – 1.18 m in Pernis. In terms of the mean θv, you see a gradual increase from the upstream area (Pernis) to the downstream area (Maasvlakte). The increase is from 0.27 – 0.63 m in Pernis to 0.64 – 0.80 m in Botlek to 0.84 – 1.86 m in Maasvlakte. However, it is not clear if this is due to the Meuse or due to the existence of sublayers in the geological formation or due to some other factor. Further investigation is needed before a conclusive answer can be given. The answer for the second part is that as long θv is significantly larger than the pile diameter D (θv ≥ 4D), it does not influence the uncertainty of the computed pile base capacity. However, the mean and standard deviation of cone resistance does influence the uncertainty of the computed pile base capacities. Finally, it is observed that spatial variability does not play a role in the uncertainty of the computed pile base capacity if the coefficient of variation of the cone resistance cv (qc) is small (cv (qc) ≤ 0.15). The implication for the uncertainty of the computed pile base capacity and therefore the pile design is that one can afford to have a less accurate description of the spatial variability from using fewer CPTs if θv ≥ 4D. The same holds true if cv(qc) ≤ 0.15.
In this study, pile foundations serve as an example to assess compatibility between the EN1990 and EN1997. The deterministic Dutch pile design approach by van Mierlo & Koppejan (1956), CPT based design method, is adapted to the semi probabilistic model pile recipe in the EN1997 draft. This thesis assesses what reliability levels are achieved by the model pile design method in draft EN1997 considering the axial bearing capacity and how these compare to the reliability targets in EN1990.
Methodology: To assess the performance of the model pile method from EN1997, the design outcome from the semi-probabilistic model pile method is compared to fully probabilistic quantification methods of the resistances and loads. Two probabilistic quantifications are used in the assessment, a Bayesian and a Student-T model. The achieved reliabilities are assessed with both the First Order Reliability Method (FORM) and Monte Carlo Simulation (MCS). Additional insight into the influence of different parameters is provided with sensitivity analysis and the calibration of partial factors. The assessment was applied in two case studies located in the Netherlands.
In both case studies, the EN1997 designs resulted in reliability levels in good agreement with the reliability targets stated in EN 1990. This suggests an agreement between the semi-probabilistic and the full probabilistic models if sufficient CPTs are used. In both case studies, EN1997 designs accounted for more model uncertainty than the probabilistic models suggest, thus partial model factor (γRd) in EN1997 may be conservative. EN1997 covers spatial variability and uncertainty due to limited observations with the correlation factor (ζ, a factor that transforms calculated to representative values, and the partial resistance factor (γRc). The coverage of uncertainty with these two factors seems to be rather low, especially for situations with few CPTs available (less than 10), although the results seem to depend strongly on the degree of spatial variability in the CPT field. In the case of homogeneous soil conditions between observations, EN1997 design methods led to over-conservative designs for low numbers of observations. If the variability between limited observations (less than 10 CPTs) was high, designs are assessed to be less reliable than EN1990 requires.
Overall, the results suggest good agreement of the semi-probabilistic design methods from EN1997 with the reliability targets defined in EN1990, for designs based on sufficient observations. The sensitivity analysis and isolation of the resistance uncertainty showed for the two cases that the uncertainty of the resistance has the dominating influence on the reliability of the piles, suggesting a low impact of complex stochastic load models. The latter finding suggests that probabilistic treatment of the resistance may be sufficient for assessing pile reliability in practice, while design values could be used for the loads.","Eurocode 7; EN1997; Probabilisitic Analysis; probabilistic assessment; Pile foundations; EN1990; Eurodoe 0; Monte Carlo; FORM; CPT; Koppejan","en","master thesis","","","","","","","","","","","","Civil Engineering","",""
"uuid:d5fd431b-3484-41e1-84f8-1303c6ca82ed","http://resolver.tudelft.nl/uuid:d5fd431b-3484-41e1-84f8-1303c6ca82ed","Modelling a Cone Penetration Test in Dry Sand using the Material Point Method: A State-Dependent Constitutive Model Approach","Bierma, Sybren (TU Delft Civil Engineering and Geosciences)","Hicks, M.A. (mentor); Pisano, F. (graduation committee); Askarinejad, A. (graduation committee); Martinelli, Mario (graduation committee); Hoefsloot, Flip (graduation committee); Delft University of Technology (degree granting institution)","2022","The numerical modelling of a cone penetration test (CPT) has long been a challenging task due to the large deformations associated with the penetration of a CPT. Recent developments in advanced numerical methods have shown promising results in overcoming these difficulties by using the Material Point Method (MPM). In this thesis it is researched whether the MPM is able to reliably produce CPT results in dry sand by using a state-dependent constitutive model. Calibration chamber (CC) tests are modelled for dry sand and results are compared with experimentally performed CC tests in the laboratory. Features regarding the numerical setup and applied boundary conditions which quantitatively influence modelling results are identified and assessed before the model is validated to real CC test data. Validation results show that the model is able to accurately produce cone resistance values for different types of sand for soil states that can be categorised as moderately-dense to dense. Last, it is shown how parameters within the constitutive framework affect the model output and a quantification of the sensitivity of the parameters to model results is presented.","sand; CPT; soil state; constitutive relations; MPM; calibration chamber tests","en","master thesis","","","","","","","","","","","","Geo-Engineering","",""
"uuid:a2bd2d0a-9bea-4d00-9699-dd80b5ddd5c3","http://resolver.tudelft.nl/uuid:a2bd2d0a-9bea-4d00-9699-dd80b5ddd5c3","Probabilistic identification of soil stratigraphy using CPT data","de Zeeuw, Guido (TU Delft Civil Engineering and Geosciences)","Varkey, D. (mentor); Hicks, M.A. (mentor); van den Eijnden, A.P. (mentor); Delft University of Technology (degree granting institution)","2021","The deterministic approach for interpreting CPT soil profiles poses the serious limitation of not taking data uncertainty into account. Therefore, a Bayesian model was developed by Wang et al. (2013) that, for a given CPT profile, determines the most probable number of soil layers and most probable soil layer thicknesses by simulating and comparing multiple ‘model classes’ with different complexities. In this study, this proposed model is implemented into the Python coding environment after which the functionality is verified by conducting a case study on a 23 푚 CPT profile from the Groningen area (NE Netherlands). For the given CPT profile, the model distinguishes 6 separate soil layers from which the position and thickness are in agreement with the deterministic analysis and the available borehole data. However, the case study suggests that the model fails to correctly identify the most probable soil types for CPT measurements within the vicinity of the edges of the Robertson chart. This is most-likely related to a “cut-off”-effect of the joint Gaussian distribution describing the uncertainty of a single datapoint. A subsequent study on the integration of the statistical parameters within the model is therefore required. Additionally, the code includes several optimizing strategies, but remains time consuming for very complex model classes. Further optimization is suggested to achieve greater model precision and efficiency.","Bayesian; CPT; soil strata; probabilistic identification; Wang et al. (2013)","en","student report","","","","","","https://github.com/guidodezeeuw/Bayesian Github with code","","","","","","Geo-Engineering","Additional Thesis",""
"uuid:feab3710-a42d-4ba6-a2d2-40e7b4fa619a","http://resolver.tudelft.nl/uuid:feab3710-a42d-4ba6-a2d2-40e7b4fa619a","Quantifying track condition based on soil properties","Schoorl, Jinse (TU Delft Civil Engineering and Geosciences)","Markine, V.L. (mentor); Nunez, Alfredo (graduation committee); El Laham, K. (graduation committee); Delft University of Technology (degree granting institution)","2021","Soil is an important part of a railway track structure. It provides the foundation for the structure and distributes the imposed loads. Consequently, soil has an influence on the condition of a track structure and a low quality soil can ultimately cause failure of the track structure. To be able to include the condition of a soil in the assessment on track quality, the following research question is posed:
“What is the quantitative influence of soil on the track condition for the railway tracks between Utrecht and Den Bosch?”
To be able to answer the research question, first the influence of soil on track condition is distinguished. The most important failure types, progressive shear failure and excessive plastic deformation, are best characterised by the strength of the soil and the deformation of the tracks respectively. For these characteristics a method is developed, which assesses the track condition. For strength a bearing capacity approach is used and for deformations a beam-on-an-elastic-foundation model is used. The process of the method is illustrated by executing it for a specific trajectory, being the Utrecht-Den Bosch line in the Netherlands. To take into account the variability of different soils, the soil type and some specific soil parameters derived from Cone Penetration Tests are determined and applied in the calculations for the assessment.
From the results can be concluded that for the Utrecht-Den Bosch line, the track quality considering passenger trains will either deteriorate limitedly or not at all. This is the case for quality related to both strength and deformation. For cargo trains, the quality related to deformation is such that limited deterioration can be expected. For strength, however, a large number of sections has a condition varying between the failure level and the desired level, which means that significant deterioration is possible, though, there are sections with higher quality as well.
Three miniature CPTs are designed with diameters of 4, 7.5 and 9.5 millimeters. Each design has certain applications and can be used in specific scenarios. All three designs include modular load cells and sub-parts that can be replaced and altered. Each proposed device consists of a modular load cell designed based on required material properties to experience a minimum amount of 500 micro-strain without buckling. The first design, with a cone diameter of 4 millimeters, can be used in any container with a minimum width of 12 centimeters and for soil samples with a maximum average grain size of 200 micrometers. The second design, with a cone diameter of 7.5 millimeters, can be used in containers with a minimum width of 22.5 centimeters and is applicable to soil samples with a maximum average grain size of 270 micrometers. The final design, with a diameter of 9.5 millimeters, is meant to be used in sample containers of widths above 28.5 centimeters and for soil samples with a maximum average grain size of 340 micrometers. The designs are then evaluated with regards to manufacturing costs and feasibility. An estimation is made based on previously designed and patented devices and material catalogues provided by manufacturers. The cost of the first two designs are estimated to amount to 1580 to 2080 Euros, whereas the third design is estimated to cost 3080 to 3580 euros due to temperature compensated pore-pressure sensor that is included in the design. Upon further evaluation, the first design with a diameter of 4 millimeters is chosen as the most feasible and practical concept due to applicability and practicality of the design.","Cone Penetration Test; CPT; Centrifuge modelling; Design Proposal","en","student report","","","","","","","","","","","","Applied Earth Sciences","",""
"uuid:2b2587e5-aa76-458b-af41-f21cd35d58d9","http://resolver.tudelft.nl/uuid:2b2587e5-aa76-458b-af41-f21cd35d58d9","Development of a new CPT averaging technique and review of existing CPT based methods for the calculation of total pile capacity","de Boorder, Munta (TU Delft Civil Engineering and Geosciences)","Gavin, Kenneth (mentor); Korff, M. (graduation committee); Lanzafame, R.C. (graduation committee); de Lange, Dirk (graduation committee); Delft University of Technology (degree granting institution)","2019","Over the last couple years, a number investigations into the α factors used for the cone penetration test (CPT) based calculation methods for the base and shaft capacity of driven piles have been carried out. These investigation, express different concerns and limitation of the currently used CPT based calculation methods. Prompting the need for further investigation into the consistency of these methods.For the base capacity calculation methods, the αp factor used is accompanied by a cone resistance (qc ) averaging technique. However, some limitation have been found for the currently used qc averaging technique, which affects the consistency and accuracy of the base capacity calculations when a constant αp factor is used, namely, a dependency with penetration depth. Presentiments by Randolph (2003) & White and Bolton (2005), suggest that a single, constant αp factor can be used when an appropriate averaging technique is applied in combination with the inclusion of the residual loads present in a pile. Hence, a new CPT averaging technique was developed during this study. The goal of this new averaging technique is to find an accurate and consistent averaging technique, which can be used in combination of a single, constant αp factor. The new CPT averaging technique was calibrated using a series of high quality CPT laboratory tests with varyingsoil deposits. Comparisons were then made between the new and existing averaging techniques, as well as, base capacity calculation methods by applying the different averaging techniques to the Deltares pile load test database. Lastly, the effect of residual loads were investigated by applying the averaging techniques to 4 well documented pile load tests where distinctions between residual loads were made. The investigation carried out in this report concluded that the new CPT averaging technique, developed in this study, was more accurate than the other investigated CPT averaging techniques, when comparisons were made with the CPT laboratory tests. This was also the case when comparing the CPT averaging techniques applied to the pile load database. Although the pile load database demonstrated that the new averaging technique had the least spread in results, a dependency with embedment length in the sand bearing layer was still present. This effect was not removed when pile load tests including residual loads were considered, as predicted by Randolph (2003) & White and Bolton (2005). However, the limited number of these tests calls for further research in order to confirm any conclusions.For the shaft capacity calculation methods, the αs factor used by the Dutch norm in particular, NEN-9997- 1, was investigated. This is because the formulation of the NEN-9997-1 calculation method is believed to be too simplistic (van Tol, Stoevelaar, Bezuijen, Jansen, & Hannink, 2013). Comparisons between a variety of shaft capacity calculation methods were made by applying the calculation methods to the Deltares pile load test database and to the 4 well documented pile load tests where distinctions between residual loads were made, in order to look into the effect of residual load on the accuracy of shaft capacity calculation methods.Additionally, results from the research carried out in this report into the αsfactor used by the Dutch norm, concluded a presence of a strong correlation between the αs of sand layers and friction fatigue terms used in other shaft capacity calculation methods. This can be used in the future to improve the current shaft capacity calculation method used by the Dutch norm. ","Pile driving; Capacity; CPT-based correlations; CPT; averaging distance; pile foundations","en","master thesis","","","","","","","","","","","","Geo-Engineering","",""
"uuid:7203d650-9e8d-40ec-9fc5-ee46fbe6da43","http://resolver.tudelft.nl/uuid:7203d650-9e8d-40ec-9fc5-ee46fbe6da43","Analysis of the quantity of CPTs in relation to the inner slope stability","Joosten, Stan (TU Delft Civil Engineering and Geosciences; TU Delft Hydraulic Engineering)","Reinders, Kristina (mentor); Kok, Matthijs (mentor); Askarinejad, Amin (mentor); de Greef, J. (mentor); Delft University of Technology (degree granting institution)","2018","The introduction of the new 'Waterwet' led to the retesting of a lot of primary flood defences within the Netherlands, sequentially certifying a lot of levees as unsafe regarding inner slope stability. To test or design a levee an adequate amount of soil investigation is required to indicate the presence of different soil types, stratification and to estimate the relevant soil parameters. The spatial spreading and the fact that the number of cone penetration tests (CPT) and boreholes within a levee to determine geotechnical parameters and stratification are limited, means that the estimated parameters always contain uncertainties. Nevertheless current guidelines do not cover the minimum CPT interval size or the uncertainty in undrained shear strength in longitudinal direction. In this thesis it is analysed how the quantity of CPTs in longitudinal direction affect the estimated undrained shear strength, and how this influences the probability of failure regarding inner slope stability.
A 5 km long levee containing a continuous peat and clay layer along the Markermeer is specified as research area. In this area the CPT interval size in longitudinal direction is 100 m. The inner slope stability is analysed with D-Geo Stability (level I reliability approach) and the Probabilistic Toolkit (level II reliability approach). Although simplifications within the model ensure that only layer thickness and undrained shear strength vary in longitudinal direction, the calculated safety factors still show a lot of fluctuation. The probabilistic stability analysis show that in the considered research area, the undrained shear strength has a larger influence on the probability of failure in comparison to layer thickness, unit weight and outside water level.
As the CPT interval size increases in longitudinal direction, the minimum safety factor could be overseen, which can lead to optimistic reliability estimations. The theory of information entropy is used to analyse the effect of changing CPT interval sizes on the estimation of the undrained shear strength. Information entropy measures the amount of uncertainty/information in a dataset. A new partial factor (the ‘spatial factor’) is proposed based on the normalized entropy. The proposed spatial factor accounts for spatial uncertainty in the estimated undrained shear strength in longitudinal direction and assigns additional safety when the CPT interval size is larger than 100 m for the considered research area. This methodology promotes the collection of additional data, which is thought to be the basic starting point for any partial factor that is assigned to cover epistemic uncertainties.