Thèse de doctorat : Mécanique et énergétique : Vandoeuvre-les-Nancy, INPL : 2005. / Titre provenant de l'écran-titre. Bibliogr.

Reproduction de : Thèse de doctorat : Énergétique et transferts : Toulouse, INPT : 2006. / Titre provenant de l'écran-titre. Bibliogr. 25 réf.

Rapport de recherche bibliographique de master professionnel 2e année : Ingénierie documentaire : Villeurbanne, ENSSIB : 2005. Rapport de recherche bibliographique de master professionnel 2e année : Ingénierie documentaire : Lyon 1 : 2005. / Texte intégral.

Thèse de doctorat : Chimie-physique. Chimie et sciences des matériaux : Paris 12 : 2007. / Titre provenant de l'écran-titre. Bibliogr. : 242 réf.

Reproduction de : Thèse de doctorat : Énergétique et transfert : Toulouse, INPT : 2006. / Titre provenant de l'écran-titre. Bibliogr. 179 réf.

Reproduction de : Thèse de doctorat : Chimie, Sciences des Matériaux : Clermont-Ferrand 2 : 2005. / Thèse avec annexes. Titre provenant de l'écran-titre. Bibliogr. p. 163-167.

Corroded steel in concrete is a structural issue that plaques concrete structures in coastal regions. Traditionally corroded steel strength is calculated from a distributed area loss due to corrosion over the entire surface of the steel and reducing the capacity accordingly. In reality, corrosion attacks localized regions creating pits and reducing the cross section in a small region which amplifies the effects of corrosion. Stress concentrations at the corrosion pitting damage may further reduce the tensile capacity of the steel. A study of corrosion damage and strength associated with pitting damage can assist in understanding the ultimate tensile capacity of corroded steel strands, better correlations are needed to estimate actual strength of damaged steel. The focus of this thesis is on seven-wire prestress steel strands with various stages of induced corrosion. Each strand has been documented, profiled, and measured in order to correlate physical damage with ultimate capacity.

When a rigid shaft such as a jacked pile or the sleeve of a cone penetrometer penetrates soil, the soil mass at the shaft tip fails. This failed soil mass flows around the shaft surface and creates a disturbed soil zone. The soil in this zone, which is at a failure or critical state (CS), flows and behaves like a viscous fluid. During continuous penetration, the shaft surface is subjected to an additional viscous shear stress above the static shear stress (interfacial solid friction). The total resistance on the shaft in motion is due to the static and viscous shear components. Current methods of calculating the penetration resistance in soils are based on static interfacial friction, which determine the force required to cause failure at the shaft-soil interface and not the viscous drag. The main aim of this research is to understand the viscous soil resistance on penetrating shafts in clays.This research consists of two components. First, a theoretical analysis based on creeping flow hydrodynamics is developed to study the viscous drag on the shaft. The results of this analysis reveal that the size of the CS zone, the shear viscosity of the soil and velocity of the shaft influence the viscous drag stress. Large increases in viscous drag occur when the size of the CS zone is less than four times the shaft radius.Second, a new experimental procedure to estimate the shear viscosity of clays with water contents less than the liquid limit is developed. Shear viscosity is the desired soil parameter to estimate viscous drag. However, there is no standard method to determine shear viscosity of clays with low water contents (or Liquidity Index, LI). Soils can reach CS for water contents in the plastic range (LI<1) and exhibit viscous behavior. The fall cone test is widely used to interpret the index (liquid and plastic limit) and strength properties of clays. In this study the existing analysis of the fall cone test is reexamined to discern the viscous drag as the cone penetrates the soil. This reexamination shows that the shear viscosity of clays with low water contents (LI<1.5) can be estimated from time-penetration data of the fall cone. Fall cone test results on kaolin show that the shear viscosity decreases exponentially with an increase in LI.The results of this research can be used to understand practical problems such as jacked piles in clays, cone penetrometer sleeve resistance and advancement of casings in soil for drilling or tunneling operations.

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:  skaičiavimas pagal polių bandymų metu gautus duomenis;  skaičiavimas pagal laboratorinių tyrimų metu gautus duomenis;  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]

Large diameter piles have increasingly been used, especially for offshore foundations. Most of the piles that have been used offshore have been open-ended. There is evidence from previous work that closed-ended piles have merits over open-ended piles; they have a greater ultimate axial capacity and are easier to drive than open-ended piles of the same outer diameter. However, because a greater volume of soil is displaced, closed-ended piles give rise to much greater ground heave. This additional heave may cause unacceptable distortion to the structure as each leg is fixed to the sea-bed in turn. For this reason, this research was commissioned. Laboratory studies of ground heave around driven open- and closed-ended piles (16mm o.d.) were carried out. Two different types of specimen reconstituted from Speswhite Kaolin were prepared; semi-cylindrical and full cylindrical specimens each 450mm in diameter and about 450mm in height. The semi-cylindrical specimens were used to obtain qualitative data about the movements of soil around the driven pile. The full cylindrical specimens were used to take accurate measurements of the ground heave during pile driving and to study the influence of the ground heave on a small surcharged collar through which a pile was driven. A further series of tests investigated the effect of ground heave when a group of piles was driven through a larger surcharged collar which was used to represent the mudmat of an offshore structure. The lateral movement of soil at around the mid-depth of a driven pile agreed with the cavity expansion model (plane strain analysis) assuming undrained conditions and no vertical movement. Closed-ended piles were found to generate about four times the magnitude of ground heave compared to open-ended piles with an area ratio of 34%. Ground heave appeared to be unaffected by overconsolidation ratio and rate of pile driving (22 to 150 blows/min.). However, maximum vertical consolidation pressure seemed to have a small effect. A remarkably good agreement was obtained between the field data and the results of this investigation when both were made dimensionless. The surcharged collar and model mudmat generally settled during pile driving. However, when very low surcharge pressures were used, the collar and mudmat were lifted up. For pile groups, the surcharged mudmat tilted towards the pile being driven. The magnitude of this tilt for the mudmat was greater when closed-ended piles were used.