The research carried out in this thesis has concentrated on the application of numerical solutions to geotechnical penetration problems in offshore engineering. Several important issues closely relevant to deep-water oil and gas developments were investigated, covering installation of suction caisson foundations, interpretation of fullflow penetrometers and shallow penetration of a cylindrical object (submarine pipeline or T-bar), all in clayey sediments such as are often encountered in deep-water sites. These problems are commonly characterised by large vertical movements of structural elements relative to the seabed. A large deformation finite element method was adopted and further developed to simulate these challenging problems, referred to as Remeshing and Interpolation Technique with Small Strain. In this approach, a sequence of small strain Lagrangian increments, remeshing and interpolation of stresses and material properties are repeated until the required displacement has been reached. This technique is able to model relative motion between the penetrating objects and the soil, which is critical for evaluating soil heave inside the caissons, the effect of penetration-induced remoulding on the resistance of full-flow penetrometers, and influence of soil surface heave on the embedment of pipelines. '...' Simple expressions were presented allowing the resistance factors for the T-bar and ball penetrometers to be expressed as a function of the rate and strain-softening parameters. By considering average strength conditions during penetration and extraction of these full-flow penetrometers, an approximate expression was derived that allowed estimation of the hypothetical resistance factor with no strain-softening, and hence an initial estimate of the stain-rate dependency of the soil. Further simulations of cyclic penetration tests showed that a cyclic range of three diameters of the penetrometers was sufficient to avoid overlap of the failure mechanism at the extremes and mid-point of the cyclic range. The ball had higher resistance factors compared with the T-bar, but with similar cyclic resistance degradation curves, which could be fitted accurately by simple expressions consistent with the strain-softening soil model adopted. Based on the curve fitting, more accurate equations were proposed to deduce the resistance factor with no strain-softening, compared with that suggested previously based on the resistances measured in the first cycle of penetration and extraction. The strain-rate dependency was similar in intact or post-cyclic soil for a given rate parameter. The resistance factor for the post-cyclic condition was higher than that for the initial conditions, to some degree depending upon soil sensitivity and brittleness parameter. For the shallow penetration of a cylindrical object, the penetration resistance profile observed from centrifuge model tests was very well captured by the numerical simulation. The mechanism of shear band shedding was reproduced by the numerical technique, although the frequency of the shear band generation and the exact shape of the heave profile were not correctly captured, which were limited by the simple strainsoftening soil model adopted.

In any geotechnical design procedure, the fundemantal point to be initially clearified is the characterization of existing soil profile at a site. This requires a great deal of planning a suitable site investigation program including borings, sampling, laboratory and in situ testing etc. Laboratory and in-situ (field) tests are important tools leading to the estimation of soils properties in geotechnics. Beside laboratory tests, the measurement of engineering properties in situ is a continuously growing and developing trend, particularly in materials difficult to obtain perfect undisturbed samples. For the purpose of this study, two large volumed geotechnical investigation reports are collected from a wide archive of 30 years experiences. Different soil types are encountered during the study like alluvial deposits of soft to stiff cohesive materials, hard clays in appearance of highly weathered rocks. The in-situ tests mostly being focused and studied on are &ldquo / Pressuremeter Test&rdquo / and &ldquo / Standard Penetration Test&rdquo / on cohesive materails. Over 350 standard penetration test results are recorded together with the pressuremeter results of relevant soils. Besides, the corresponding laboratory test results of oedometer, triaxial loading and all index properties of soils are assembled. The results of in-situ tests are evaluated together with the results of laboratory tests performed on the samples obtained from related sites. The correlations between in-situ &amp / laboratory test results on shear strength, compressibility and deformation characteristics of soils are analysed and compared with the existing correlations in literature. The correlations are generally obtained to be in agreement with the ones in common literature in cases where the soil conditions, particularly saturation, are same in both laboratory and in-situ tests.

Although silt and clay mixtures were mostly considered to be resistant to cyclic loading due to cohesional components of their shear strength, ground failure case histories compiled from fine grained soil profiles after recent earthquakes (e.g. 1994 Northridge, 1999 Adapazari, 1999 Chi-Chi) revealed that the responses of low plasticity silt and clay mixtures are also critical under cyclic loading. Consequently, understanding the cyclic response of these soils has become a recent challenge in geotechnical earthquake engineering practice. While most of the current attention focuses on the assessment of liquefaction susceptibility of fine-grained soils, it is believed that cyclic strain and strength assessments of silt and clay mixtures need to be also studied as part of complementary critical research components. Inspired by these gaps, a comprehensive laboratory testing program was designed. As part of the laboratory testing program 64 stress-controlled cyclic triaxial tests, 59 static strain-controlled consolidated undrained triaxial tests, 17 oedometer, 196 soil classification tests including sieve analyses, hydrometer, and consistency tests were performed. Additionally 116 cyclic triaxial test results were compiled from available literature. Based on this data probability-based semi-empirical models were developed to assess liquefaction susceptibility and cyclic-induced shear strength loss, cyclically-induced maximum shear, post-cyclic volumetric and residual shear strains of silt and clay mixtures. Performance comparisons of the proposed model alternatives were studied, and it is shown that the proposed models follow an unbiased trend and produce superior predictions of the observed laboratory test response. Superiority of the proposed alternative models was proven by relatively smaller model errors (residuals).

Organic materials are ubiquitous in the geologic environment, and can exert significant influence over the interfacial properties of minerals. However, due to the complexity in their structure and interaction with soil solids, their impact has remained relatively unquantified. This study investigated the engineering behaviors of organoclays, which were synthesized in the laboratory using naturally occurring clay minerals and quaternary ammonium compounds of controlled structure and density of loading. Organic cations were chosen to study the effects of functional group structure and size. The laboratory investigation showed that the presence of the organic cations on the mineral surfaces led to increased hydrophobicity of all clays tested. Conduction studies on the electrical, hydraulic, and thermal properties of the organoclay composites suggested that increasing the total organic carbon content resulted in decreased electrical and thermal conductivity, but increased hydraulic conductivity, due to the reduced swelling of the base clay mineral phase. Electrokinetic properties of the organoclays illustrated that compared with the clay's naturally occurring inorganic cations, exchanged quaternary ammonium cations were more likely bound within a particle's shear plane. Consequently, organoclays had less negative zeta potential than that of unmodified bentonite. Increasing the length of one carbon tail was more effective at binding organic cations within the shear plane than increasing the size of the cation, when compared on the basis of total organic carbon content. In terms of large strain strength, the modified organic clays exhibited increased shear strength, in part owing to the reduction in water content caused by the presence of the hydrophobic organic layering. Shear strength increased with single carbon tail length or with cation size, although the latter effect tended to reach a plateau as the length of the four short cation tails increased from 2 to 4. In terms of small strain behavior, the shear modulus was shown to be a function of the total organic carbon content. It is believed that number of particle contacts increased as the organic carbon content increased. Stiffness increased as either the size of the cation or the total organic carbon content was increased. Damping also increased as the organic loading was increased, with the organic phase acting as an energy dissipation mechanism.

Fiber reinforcement is being widely used in concrete tunnel linings these days. Using fiber reinforcement can save not only cost, but also labor and time spent on construction. However, many owners hesitate to incorporate fiber reinforcement in tunnel lining due to lack of experience with and knowledge of the behavior of fiber reinforced concrete (FRC) In this study, fiber reinforced concrete was made with various kinds of fibers such as steel fiber, macro-synthetic fiber and hybrid fiber (a blend of macro-synthetic fiber and glass fiber). Many experimental tests were performed to investigate the compressive, flexural and shear behavior of fiber reinforced concrete. In addition to the structural capacity of FRC, the distribution of fiber reinforcement inside the concrete matrix was investigated. Test results of these experimental tests were thoroughly examined to compare and quantify the effects of fiber reinforcement. Next, the test results were used to generate axial force-bending moment interaction diagrams based on current design approaches. In addition, the current design approaches were modified to estimate the accurate and exact value of bending moment. Fiber reinforcement clearly improved the structural performance of tunnel lining. The post-peak flexural and shear strength was significantly influenced by the type and amount of fiber reinforcement. / text

Necessary information about soil properties, which is needed for designers and constructors, is obtained in each construction site while examining physical and mechanical properties of soils. Soil strength parameters and using them determined soil bearing resistance usually are defined with some errors. If we know the reasons of errors, disadvantages of testing equipment could be eliminated, methodology of data evaluation could be developed, soil parameters could be determined more precisely and foundation designed more economically. At present triaxial and direct shear tests are the most common tests for determination of soil shear strength parameters in laboratories. Different values of soil shear strength parameters are determined using laboratory equipment of various types. Triaxial test is the most widely used method for determination of soil shear strength parameters. This is one of the most reliable methods to model stress-strain state of ground. It is assumed that soil sample deforms uniformly during the triaxial test. But it is not often the case that a sample in triaxial apparatus deforms uniformly. Questions arise, what is stress-strain distribution in soil sample, when a load is transmitted in a prescribed way? What influence does a non-uniformity have on the soil strength parameters and on foundation size calculated using determined soil strength parameters? Why sandy soil strength parameters obtained from triaxial test are bigger than the one’s, obtained... [to full text] / Projektuojant ir statant įvairius pramoninius ir civilinius pastatus, visada reikalingi duomenys, kurie apibūdintų gruntų, sudarančių pastatų pagrindus, fizines ir mechanines savybes. Tokia projektuotojams ir statybos specialistams būtina informacija gaunama tiriant gruntų fizines, mechanines savybes kiekvienoje statybų aikštelėje. Šių savybių rodikliai ir pagal juos apskaičiuotas pagrindo stiprumas nustatomi su tam tikromis paklaidomis. Atskleidus tų paklaidų priežastis, šalinami tyrimo prietaisų trūkumai, tobulinami tyrimo duomenų apdorojimo metodai, tiksliau nustatomi grunto stiprumo rodikliai, ekonomiškiau projektuojami pamatai. Šiuo metu grunto kerpamojo stiprumo rodikliai dažniausiai nustatomi laboratorijose triašio slėgio ir tiesioginio kirpimo aparatais. Šių savybių rodikliai nustatyti įvairių konstrukcijų prietaisais gaunami skirtingi. Įtempimų ir deformacijų būvis grunto pagrinde geriau modeliuojamas triašio slėgio aparatu nei tiesioginio kirpimo aparatu, todėl triašio slėgio aparatas šiuo metu yra plačiai naudojamas pasaulyje nustatant grunto kerpamojo stiprumo savybių rodiklius. Daroma prielaida, kad bandinys bandymo metu deformuojasi vienodai. Šis teiginys yra pagrindinė triašio bandymo idėja. Tačiau dažniausiai bandinys deformuojasi nevienodai dėl grunto bandinio viršaus ir apačios horizontalių poslinkių suvaržymo, bandinio aukščio, nepakankamo drenavimo, guminės membranos poveikio, jo savojo svorio ir kt. Baigtinių elementų metodo analizė taip pat rodo, kad... [toliau žr. visą tekstą]

Projektuojant ir statant įvairius pramoninius ir civilinius pastatus, visada reikalingi duomenys, kurie apibūdintų gruntų, sudarančių pastatų pagrindus, fizines ir mechanines savybes. Tokia projektuotojams ir statybos specialistams būtina informacija gaunama tiriant gruntų fizines, mechanines savybes kiekvienoje statybų aikštelėje. Šių savybių rodikliai ir pagal juos apskaičiuotas pagrindo stiprumas nustatomi su tam tikromis paklaidomis. Atskleidus tų paklaidų priežastis, šalinami tyrimo prietaisų trūkumai, tobulinami tyrimo duomenų apdorojimo metodai, tiksliau nustatomi grunto stiprumo rodikliai, ekonomiškiau projektuojami pamatai. Šiuo metu grunto kerpamojo stiprumo rodikliai dažniausiai nustatomi laboratorijose triašio slėgio ir tiesioginio kirpimo aparatais. Šių savybių rodikliai nustatyti įvairių konstrukcijų prietaisais gaunami skirtingi. Įtempimų ir deformacijų būvis grunto pagrinde geriau modeliuojamas triašio slėgio aparatu nei tiesioginio kirpimo aparatu, todėl triašio slėgio aparatas šiuo metu yra plačiai naudojamas pasaulyje nustatant grunto kerpamojo stiprumo savybių rodiklius. Daroma prielaida, kad bandinys bandymo metu deformuojasi vienodai. Šis teiginys yra pagrindinė triašio bandymo idėja. Tačiau dažniausiai bandinys deformuojasi nevienodai dėl grunto bandinio viršaus ir apačios horizontalių poslinkių suvaržymo, bandinio aukščio, nepakankamo drenavimo, guminės membranos poveikio, jo savojo svorio ir kt. Baigtinių elementų metodo analizė taip pat rodo, kad... [toliau žr. visą tekstą] / Necessary information about soil properties, which is needed for designers and constructors, is obtained in each construction site while examining physical and mechanical properties of soils. Soil strength parameters and using them determined soil bearing resistance usually are defined with some errors. If we know the reasons of errors, disadvantages of testing equipment could be eliminated, methodology of data evaluation could be developed, soil parameters could be determined more precisely and foundation designed more economically. At present triaxial and direct shear tests are the most common tests for determination of soil shear strength parameters in laboratories. Different values of soil shear strength parameters are determined using laboratory equipment of various types. Triaxial test is the most widely used method for determination of soil shear strength parameters. This is one of the most reliable methods to model stress-strain state of ground. It is assumed that soil sample deforms uniformly during the triaxial test. But it is not often the case that a sample in triaxial apparatus deforms uniformly. Questions arise, what is stress-strain distribution in soil sample, when a load is transmitted in a prescribed way? What influence does a non-uniformity have on the soil strength parameters and on foundation size calculated using determined soil strength parameters? Why sandy soil strength parameters obtained from triaxial test are bigger than the one’s, obtained... [to full text]

Šiame baigiamajame magistro darbe nagrinėjama polistireninio putplasčio stiprumo savybės. Teorinėje dalyje pateikta literatūros analizė, bendros žinios apie polistireninį putplastį, gamybos būdai, panaudojimo galimybės. Išnagrinėta trijų didžiausių gamintojų Lietuvoje siūloma produkcija. Apžvelgti reikalavimai pastatų atitvarų šiluminei varžai, išnagrinėta termoizoliacinio sluoksnio storio pokytis nuo TSRS laikų iki dabar. Eksperimentinėje dalyje aprašomos naudotos medžiagos; jų charakteristikos; gniuždomasis stipris; šliejamasis stipris; išnagrinėta skirtingo tankio bandinių mikrostruktūra ir makrostruktūra. Aprašomi rezultatai, naudojant statistinės analizės programą atliekama jų analizė, suformuluojamos išvados. / The present work of Master degree studies analyzes the properties of expanded polystyrene.Theoretical par of this work introduces analysis of references, general information on expanded polystyrene, manner of production and fields of application. The work analyzes production offered by three biggest manufacturers in Lithuania, reviews the requirements applicable to thermal resistance of enclosures of the building, analyses alteration of thickness of a heat insulation layer comparing the situation in Soviet Union time and nowadays. Experimental part describes the used material, their properties, compressive strength, shear strength; analyses microstructure and macrostructure of samples of different density. The work presents the results and analysis of the results by applying software of statistical analysis; formulation of conclusions.

A landslide occurred during the construction of the Giresun &ndash / Espiye road between Km: 1+030 &ndash / 1+170 in April 2003. Investigating the causes and mechanism of this slope failure along with suggesting a proper stabilization technique is aimed in this study. For that purpose, a detailed site investigation study, including engineering geological mapping, drilling work, in situ and laboratory tests, was performed. Weathered tuffite, tuffite, flysch and dacitic tuffite, from top to bottom, are the major units in the study area. A &ldquo / translational slide&rdquo / occurred in completely weathered tuffite owing to the disturbance of the stability of the slope by the excavations performed at the toe of the slope / particularly the foundation excavation for the restaurant building and for the road cut for the Giresun &ndash / Espiye road. After establishing the model of the landslide in detail, shear strength parameters of the failure surface were determined by the back analysis method as &quot / cohesion&quot / =2.5 kN/m2 and &quot / friction angle&quot / =9&deg / . Toe buttressing, ground water and surface water drainage options were considered for stabilizing the slope. For the back analysis calculations, the Morgenstern-Price and Spencer methods were used with the aid of the SLOPE/W computer program.

The purposes of this study are to investigate the possible effects of variables like testing depth, length to diameter ratio of the probe, presence of disturbed annulus around the borehole etc. on the derived parameters from the pressuremeter test, and to develop possible alternative methods for the determination of undrained shear strength of cohesive soils, and cohesion and internal friction angle of intermediate geomaterials. For this purpose numerical simulations of pressuremeter test were performed. In the study, it is also aimed to investigate the effect of rock quality designation (RQD) or some other rock mass parameters such as geological strength index (GSI) and rock mass rating (RMR) and intact rock strength on the deformation modulus determined from the pressuremeter test. To accomplish this task, Dikmen greywackes, weathered andesites and mudrocks exposed around Ankara - Sincan region were selected for field and laboratory studies. Empirical relationships using GSI, RMR, RQD were developed for the estimation of deformation modulus of greywackes and mudrocks cropping out around Ankara. Numerical simulations revealed the presence of disturbed annulus around the borehole causes underestimation of deformation modulus and overestimation of undrained shear strength. Test depth has no effect on the deformation modulus and undrained shear strength / the effect of length to diameter ratio of the probe on the deformation modulus is minor where as it causes overestimations of undrained shear strength. Pore pressure dissipation in low permeability soils around the pressuremeter was studied using numerical simulations. These analyses suggest that for permeabilities lower that 10-10 m/sec there is no pore pressure dissipation around the pressuremeter probe. It was determined that the inverse analysis yielded successful results for the determination of shear strength parameters of intermediate geomaterials.