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A database with 217 cases of load tests on shallow foundations, mostly in/on granular soils, was compiled. With this information, the comparison of predicted bearing capacity using different design methods, the American Petroleum Institute Recommended Practice 2A-LRFD (API RP2A-LRFD,1989), the American Petroleum Recommended Practice 2GEO (API RP2GEO, 2011), and International Standard Organization (ISO, 2003) is carried out. The answer to which standard makes a good prediction varies with the way to define failure load from load-displacement curve. Overall, ISO has a higher prediction compared with API RP2A and API RP2GEO. For the cases with vertical concentric loading conditions, if the capacity at plastic region and is defined as failure load, then the prediction by API RP2A is closest to measured capacity. If the capacity corresponding with 10% of footing width is considered as failure load, then the API RP2A and API RP2GEO underestimate the capacity, while ISO is in a good agreement with capacity corresponding with 10% of footing width. The prediction by API RP2GEO generally has a good agreement with capacity at tangent intersection region. In most of the cases with vertical eccentric loading, all three standard underestimate the measured capacities no matter which interpreted capacities is considered as failure load, while ISO makes slightly overprediction at the lower range of eccentricities and underprediction at higher range of eccentricities for some cases. In the inclined loading condition, the prediction by API RP2GEO is minimum among the three standards, while ISO proposed the highest prediction. All three prediction underestimate the capacity under inclined loading condition. From this study, it is found that small scale load laboratory test reveals a qualitative understanding with impact of vertical eccentric and concentric inclined loading on ultimate capacities. However, it is hard to detect a clear best prediction based on small scaled laboratory load test results. The well-controlled field test results, especially the field tests with vertical eccentric and concentric inclined loading condition, are valuable to evaluate the consistency of predicted capacity by three standards. / text

<p>The purpose of this study was to build a database for point-bearing piles in dense noncohesive soil, predominantly moraine. Further, the database was analysed and areas with difficult geotechnical conditions was identified.</p><p>The database includes for point-bearing piles driven to refusal in moraine. Piles with mainly shaft friction have been excluded. Only concrete piles have been included. Geographically the database covers almost all geotechnical conditions of Sweden. The total amount of piling projects is 110 and the total amount of piles is 600.</p><p>For contractors, foundation work is usually connected with a lot of uncertainty and risk, concerning the estimating of time and cost. During the design stage of foundation construction the database can be a useful tool to estimate suitable loads on the piles.</p><p>The data was analysed further with different statistical method. Possible reasons for low bearing capacity, in some projects, have also been investigated.</p> / <p>Syftet med examensarbetet är att upprätta en databas över spetsburna pålar fastslagna i friktionsjord och morän. Vidare skall databasen analyseras för att hitta styrande parametrar samt även hitta områden med problematisk geoteknik.</p><p>Databasen omfattar spetsburna pålar som stoppslås i friktionsjord. Pålar som i huvudsak är mantelburna har uteslutits. Endast betongpålar har tagits med. Geografiskt omfattar databasen i stort sett hela Sverige. Totalt innehåller databasen 110 projekt med sammanlagt över 600 pålar.</p><p>För entreprenörer i byggbranschen är grundläggningsarbetet ofta förknippat med ekonomiska risker och osäkerhet gällande omfattning och tidsåtgång. Vid dimensionering av grundläggningsarbeten kan databasen vara till stor hjälp för att bestämma lämpliga lastnivåer. Mängden slagningsarbete och risken för bortslagna pålar kan lättare uppskattas.</p><p>Först analyserades olika påltyper utan ytterligare urvalskriterier. Vikten av att filtrera informationen blev då tydlig, eftersom resultatet blev svårtolkat och inga markanta samband kunde urskiljas. Med databasen som grund har materialet vidare analyserats med hjälp av statistiska metoder. Orsaken till låga bärförmågor vid ett urval av projekt har även kartlagts.</p>

Granular materials are in abundance in nature and are estimated to constitute over 75% of all raw materials passing through the industry. Granular or particulate solids are thus of considerable interest to many industrial sectors and research communities, where many unsolved challenges still remain. This thesis investigates the micro- and macro-phenomena in densely packed particulate systems by means of the Discrete Element Method (DEM), which is a numerical tool for analysing the internal complexities of granular material as the mechanical interactions are considered at the grain scale. It presents an alternative approach to phenomenological continuum approaches when studying localisation problems and finite deformation problems in granular materials. In order to develop a comprehensive theoretical understanding of particulate matter and to form a sound base to improve industrial processes, it is desirable to study the mechanical behaviour of granular solids subject to a variety of loading conditions. In this thesis, three loading actions were explored in detail, which are biaxial compression, rigid object penetration and progressive formation of granular piles. The roles of particle shape and contact friction in each of these loading scenarios were investigated. The resulting packing structures were compared and studied to provide a micromechanical insight into the development of contact force network which governs the collective response. The interparticle contact forces and displacements were then used to evaluate the equivalent continuum stress and strain components thus providing the link between micro- and macroscopic descriptions. The information collected from the evolution of strong contact network illustrates the underlying mechanism of force transmission and propagation. DEM simulations presented in this thesis demonstrate strong capability in predicting the bulk behaviour as well as capturing local phenomenon occurring in the system. The research first simulates a testing environment of biaxial compression in DEM, in which the phenomenon of strain localisation was investigated, with special attention given to the interpretation of underlying failure mechanism. Several key micromechanical quantities of interest were extracted to understand the bifurcation instability, such as force chains, contact orientation, particle rotation and void ratio. In the simulation of progressive formation of granular piles, a counterintuitive pressure profile with a significant pressure dip under the apex was predicted for three models under certain conditions. Both particle shape and preparation history were shown to be important in the resulting pressure distribution. During the rigid body penetration into a granular sample, the contact forces were used to evaluate the equivalent continuum stress components. Significant stress concentration was developed around the punch base which further led to successive collapse and reformation of force chains. Taking the advantage of micromechanical analysis at particle scale, two distinct bearing failure mechanisms were identified as the penetration proceeded. To further quantify the nature of strain mobilisation leading to failure, Particle Image Velocimetry (PIV) was employed to measure the deformation over small strain interval in association with shear band propagation in the biaxial test and deformation pattern in the footing test. The captured images from DEM simulation and laboratory experiments were evaluated through PIV correlation. This optical measuring technique is able to yield a significant improvement in the accuracy and spatial resolution of the displacement field over highly strained and localised regions. Finally, a series of equivalent DEM simulations were also conducted and compared with the physical footing experiments, with the objective of evaluating the capability of DEM in producing satisfactory predictions.

This thesis presents numerical techniques which have been developed to analyse three dimensional problems in offshore engineering. In particular, the three dimensional liquefaction analysis of offshore foundations on granular soils is the main subject of the thesis. The subject matter is broadly divided into four sections: 1)Development of an efficient method for the three dimensional elasto?plastic finite element analysis of consolidating soil through the use of a discrete Fourier representation of field quantities. 2)Validation of the three dimensional method through analyses of shallow offshore foundations subjected to three dimensional loading and investigation of the yield locus for foundations on purely cohesive soils. 3)Formulation of governing equations suitable for three dimensional liquefaction analyses of offshore foundations founded on granular soil, presentation of a method for liquefaction analyses, and application of the method in modified elastic liquefaction analyses of offshore foundations. 4)Application of a conventional elasto?plastic soil model in the liquefaction analyses of offshore foundations using the three dimensional finite element method. The finite element method developed in this thesis provides a rigorous and efficient numerical tool for the analysis of geotechnical problems subjected to three dimensional loading. The efficiency of the numerical tool makes it possible to tackle some of the problems in geotechnical engineering which would otherwise need enormous computing time and thus would be impractical. The accuracy of the numerical scheme is demonstrated by solving the bearing capacity problem of shallow foundations subjected to three dimensional loading. The generalized governing equations and the numerical method for liquefaction analyses presented in this thesis provide a solid base for the analysis of offshore foundations subjected to cyclic wave loading where they are founded on potentially liquefiable soil. The practicability of the numerical scheme is also demonstrated by a modified elastic liquefaction analysis of offshore foundations. The liquefaction phenomenon is redefined in the context of the conventional Mohr?Coulomb model, so that a relatively simple and practical model for elasto?plastic liquefaction analysis is presented. The three dimensional finite element method together with the numerical scheme for liquefaction analysis and the elasto?plastic soil model provide a suitable practical engineering tool for exploring the responses of offshore foundations subjected to cyclic wave loading.

The purpose of this study was to build a database for point-bearing piles in dense noncohesive soil, predominantly moraine. Further, the database was analysed and areas with difficult geotechnical conditions was identified. The database includes for point-bearing piles driven to refusal in moraine. Piles with mainly shaft friction have been excluded. Only concrete piles have been included. Geographically the database covers almost all geotechnical conditions of Sweden. The total amount of piling projects is 110 and the total amount of piles is 600. For contractors, foundation work is usually connected with a lot of uncertainty and risk, concerning the estimating of time and cost. During the design stage of foundation construction the database can be a useful tool to estimate suitable loads on the piles. The data was analysed further with different statistical method. Possible reasons for low bearing capacity, in some projects, have also been investigated. / Syftet med examensarbetet är att upprätta en databas över spetsburna pålar fastslagna i friktionsjord och morän. Vidare skall databasen analyseras för att hitta styrande parametrar samt även hitta områden med problematisk geoteknik. Databasen omfattar spetsburna pålar som stoppslås i friktionsjord. Pålar som i huvudsak är mantelburna har uteslutits. Endast betongpålar har tagits med. Geografiskt omfattar databasen i stort sett hela Sverige. Totalt innehåller databasen 110 projekt med sammanlagt över 600 pålar. För entreprenörer i byggbranschen är grundläggningsarbetet ofta förknippat med ekonomiska risker och osäkerhet gällande omfattning och tidsåtgång. Vid dimensionering av grundläggningsarbeten kan databasen vara till stor hjälp för att bestämma lämpliga lastnivåer. Mängden slagningsarbete och risken för bortslagna pålar kan lättare uppskattas. Först analyserades olika påltyper utan ytterligare urvalskriterier. Vikten av att filtrera informationen blev då tydlig, eftersom resultatet blev svårtolkat och inga markanta samband kunde urskiljas. Med databasen som grund har materialet vidare analyserats med hjälp av statistiska metoder. Orsaken till låga bärförmågor vid ett urval av projekt har även kartlagts.

Gintaras Žaržojus Polio laikomosios gebos vertinimai Lietuvos gruntuose SANTRAUKA Šiame darbe yra išnagrinėti tokie uždaviniai: 1. šiuolaikinių polio laikomosios gebos vertinimo metodų apžvalga; 2. Lietuvos kvartero nuogulos kaip polinių pamatų pagrindas; 3. vibromonolitinio polio ir pagrindo sąveikos I ribinėje būklėje fizinio modelio sudarymas. Pirmojo uždavinio sprendimui buvo trumpai išnagrinėta Europos šalių polio laikomosios gebos skaičiavimų metodikos, kurias butų galima suskirstyti į tris grupes: &#61656; skaičiavimas pagal polių bandymų metu gautus duomenis; &#61656; skaičiavimas pagal laboratorinių tyrimų metu gautus duomenis; &#61656; skaičiavimas naudojant įvairių in-sitų atliktų zondavimų duomenis. Antrajam uždaviniui išspręsti buvo sudarytas polio pagrindo laikomosios gebos vidurkinių verčių žemėlapis (M 1:1500 000). Šis žemėlapis yra sudarytas pagal pasirinktą polio modelį ir skaičiavimo metodiką (EN 1997-3). Trečiajam uždaviniui išspręsti buvo atlikti penki lauko bandymai ir išanalizuoti kai kurie šiuolaikiniai grunto ir polio santykio modeliai. Pagrindinės šio darbo išvados būtų šios: 1. polio laikomosios gebos skaičiavimo metodai įvairiose šalyse yra skirtingi dėl savitų geologinių sąlygų, dėl tyrėjų (inžinierių) subjektyvumo. Dėl metodų nesutapimo yra gaunami skirtingi to paties polio galutiniai skaičiavimo rezultatai; 2. didžiausią Lietuvos teritorijos dalį sudaro vidutinio stiprumo ir stiprūs gruntai kaip polių pagrindai; 3. pagal sudarytą hipotetinį... [toliau žr. visą tekstą] / Gintaras Žaržojus ESTIMATION FOR PILES BEARING CAPACITY IN LITHUANIAN SOILS SUMMARY In this work such tasks are analyzed: 1. Review of up-to-date pile bearing capacity estimation methods; 2. Lithuanian quaternary sediments as the base for pile foundation; 3. The creation of physical model of the vibromonolithic pile and foundation interaction while in the I marginal state. For the solution of the first task, the calculation methodology of the pile bearing capacity of the European countries’ was briefly analyzed, and it can be divided into three groups: » calculation according to the data received during pile testing; » calculation according to the data received during laboratory analysis; » calculation using the data of the various probing completed in-situ. For the solution of the second task, the map of the pile base bearing capacity average values was designed (M 1:1500 000). This map is designed according to the chosen pile model and calculation methodology (EN 1997-3). For the solution of the third task the five outdoor tests were performed and the some of the up-to-date soil and pile ratio models were analyzed. The main conclusions would be: 1. The pile bearing capacity calculation methods are different in various countries, because of the individual geological conditions and because of the subjectivity of the researchers (engineers). Due to the method discrepancy, final calculation results for the same pile are different; 2. The biggest part of the Lithuanian territory... [to full text]

The design of pile foundations in conventional geotechnical engineering practice is based on the soil mechanics principles for saturated soils. These approaches are also extended to pile foundations that are placed totally or partially above the ground water table (i.e., vadose zone), where the soil is typically in a state of unsaturated condition. Such approaches lead to unrealistic estimations of the load carrying capacity and the settlement behavior of pile foundations. Some studies were undertaken in recent years to understand the influence of the matric suction towards the bearing capacity of model pile foundations placed in unsaturated fine-grained and coarse-grained soils. The conventional   and methods were modified to interpret the contribution of shaft carrying capacity of single piles in fine-grained soils (e.g., Vanapalli and Taylan 2011, Vanapalli and Taylan 2012). Also, the conventional method has been used to understand the contribution of matric suction towards the shaft resistance in unsaturated sands (Vanapalli et al. 2010). One of the key objectives of the present research study is directed to determine the contribution of matric suction towards the bearing capacity and settlement behavior of model single pile foundations in unsaturated sands. A series of single model pile load tests were performed in a laboratory environment to study the contribution of the matric suction towards the total, shaft, and base bearing capacity of the model piles with three different diameters (i.e., 38.30, 31.75, and 19.25 mm) in two unsaturated sands (i.e., a clean commercial sand and a super fine sand). Hanging column method (i.e., plexi glass water container) was used to control the matric suction values in the compacted sands in the test tank by varying the water table. The results of the testing programs indicate the significant contribution of the matric suction towards the bearing capacity of single model piles (i.e., 2 to 2.5 times of base bearing capacity and 5 times of shaft bearing capacity under unsaturated conditions in comparison with saturated condition). The test results were interpreted successfully by modifying the conventional methods for estimating the pile shaft bearing capacity (i.e., β method) and base bearing capacity (i.e., Terzaghi 1943, Hansen 1970 and Janbu 1976). In addition, semi-empirical methods were proposed for predicting the bearing capacity of single model piles using the effective shear strength parameters (i.e., c' and ϕ') and the soil-water characteristic curve (SWCC). There is a good agreement between the measured and the predicted bearing capacity of single model piles using the semi-empirical models proposed in this study. In addition, numerical investigations were undertaken using the commercial finite element analysis program SIGMA/W (Geostudio 2007) to simulate the load-displacement (i.e., p-δ) behavior of the single model piles for the two sands (i.e., clean commercial sand and super fine sand) under saturated and unsaturated conditions. An elastic-perfectly plastic Mohr-Coulomb model that takes into account the influence of the matric suction was used to simulate the load-displacement (i.e., p-δ) behavior. The numerical approach proposed in this thesis is simple and only requires the information of the effective shear strength parameters (i.e., c' and ϕ'), the elastic modulus (i.e., Esat) under saturated conditions, the soil-water characteristic curve (SWCC), and the distribution of the matric suction with respect to depth. The approaches proposed in this thesis can be extended to determine the in-situ load carrying capacity of single piles and also simulate the load-displacement (i.e., p-δ) behavior. The studies presented in this thesis are promising and encouraging to study their validity in-situ conditions. Such studies will be valuable to implement the mechanics of unsaturated soils into geotechnical engineering practice.

This thesis presents numerical techniques which have been developed to analyse three dimensional problems in offshore engineering. In particular, the three dimensional liquefaction analysis of offshore foundations on granular soils is the main subject of the thesis. The subject matter is broadly divided into four sections: 1)Development of an efficient method for the three dimensional elasto?plastic finite element analysis of consolidating soil through the use of a discrete Fourier representation of field quantities. 2)Validation of the three dimensional method through analyses of shallow offshore foundations subjected to three dimensional loading and investigation of the yield locus for foundations on purely cohesive soils. 3)Formulation of governing equations suitable for three dimensional liquefaction analyses of offshore foundations founded on granular soil, presentation of a method for liquefaction analyses, and application of the method in modified elastic liquefaction analyses of offshore foundations. 4)Application of a conventional elasto?plastic soil model in the liquefaction analyses of offshore foundations using the three dimensional finite element method. The finite element method developed in this thesis provides a rigorous and efficient numerical tool for the analysis of geotechnical problems subjected to three dimensional loading. The efficiency of the numerical tool makes it possible to tackle some of the problems in geotechnical engineering which would otherwise need enormous computing time and thus would be impractical. The accuracy of the numerical scheme is demonstrated by solving the bearing capacity problem of shallow foundations subjected to three dimensional loading. The generalized governing equations and the numerical method for liquefaction analyses presented in this thesis provide a solid base for the analysis of offshore foundations subjected to cyclic wave loading where they are founded on potentially liquefiable soil. The practicability of the numerical scheme is also demonstrated by a modified elastic liquefaction analysis of offshore foundations. The liquefaction phenomenon is redefined in the context of the conventional Mohr?Coulomb model, so that a relatively simple and practical model for elasto?plastic liquefaction analysis is presented. The three dimensional finite element method together with the numerical scheme for liquefaction analysis and the elasto?plastic soil model provide a suitable practical engineering tool for exploring the responses of offshore foundations subjected to cyclic wave loading.