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Geotechnicans in Sweden and rest of Scandinavia have a wide experience of stability calculations in cohesive soils. The two main parameters for this type of calculations are the undrained shear strength and the preconsolidation pressure. The most common methods in Sweden to determine the undrained shear strength in field is the vane shear strength test and CPT-test, in laboratories the fall cone test is well used. To determine the preconsolidation pressure CRS-analyses are well used. For more accurate measurements the odeometer tests are more suitable. However this method is both expensive and time-consuming form of analysis from a commercial aspect. Therefore is different correlation equations used as a compliment in these different stability evaluations.  This research will focus on the empirical Hansbo Correlation and its relation to results from commercial surveys. The commercial data come from Atkins Sverige’s project data base. The results after comparing Hansbo correlation with the commercial data showed on a significant divergence, which indicate a great unsureness of the Hansbo correlation. As a result of this contingency it is of importance to take cautiousness in the use of empirical correlations in stability calculations.

A presente pesquisa apresenta resultados de uma série de ensaios de palheta de laboratório, com a finalidade de determinar a resistência não drenada de um solo residual compactado. Durante o ensaio foram realizadas medições continuas de sucção com uso de um tensiômetro de alta capacidade, disposto na base dos corpos de prova, sendo este procedimento inédito. O objetivo secundário do estudo é a avaliação de aspectos relacionados com a variação da resistência e sucção quando a distância do tensiômetro de alta capacidade é modificada com relação à superfície inferior do plano de ruptura pré-estabelecido. Para a realização destes experimentos foram modificados e adaptados equipamentos de laboratório. O estudo foi realizado com um solo residual de gnaisse compactado obtido do antigo campo experimental da Escola Politécnica da Universidade de São Paulo. O estudo constata que o valor medido da resistência não drenada é afetado pela proximidade do tensiômetro a palheta. / This research presents results of a series of mini-vane tests in order to determine the undrained shear strength of a residual compacted soil. During the tests and for the first time, continuous measurement of suction has been made using a high capacity tensiometer placed at the base of the specimen. The secondary aim of this study is to evaluate aspects related to resistance and suction variation when the distance of the high capacity tensiometer is modified in relation to the lower pre-set failure surface. For this reason laboratory equipments were modified and adapted in order to perform the study. The tests were performed with a compacted residual soil of gneiss obtained from the experimental site of the Polytechnical School of the University of São Paulo. The study showed that the undrained shear strength is affected when the vane are closer to the tensiometer.

A presente pesquisa apresenta resultados de uma série de ensaios de palheta de laboratório, com a finalidade de determinar a resistência não drenada de um solo residual compactado. Durante o ensaio foram realizadas medições continuas de sucção com uso de um tensiômetro de alta capacidade, disposto na base dos corpos de prova, sendo este procedimento inédito. O objetivo secundário do estudo é a avaliação de aspectos relacionados com a variação da resistência e sucção quando a distância do tensiômetro de alta capacidade é modificada com relação à superfície inferior do plano de ruptura pré-estabelecido. Para a realização destes experimentos foram modificados e adaptados equipamentos de laboratório. O estudo foi realizado com um solo residual de gnaisse compactado obtido do antigo campo experimental da Escola Politécnica da Universidade de São Paulo. O estudo constata que o valor medido da resistência não drenada é afetado pela proximidade do tensiômetro a palheta. / This research presents results of a series of mini-vane tests in order to determine the undrained shear strength of a residual compacted soil. During the tests and for the first time, continuous measurement of suction has been made using a high capacity tensiometer placed at the base of the specimen. The secondary aim of this study is to evaluate aspects related to resistance and suction variation when the distance of the high capacity tensiometer is modified in relation to the lower pre-set failure surface. For this reason laboratory equipments were modified and adapted in order to perform the study. The tests were performed with a compacted residual soil of gneiss obtained from the experimental site of the Polytechnical School of the University of São Paulo. The study showed that the undrained shear strength is affected when the vane are closer to the tensiometer.

Mobile offshore drilling units are being used in the Gulf of Mexico to produce oil and gas. Anchoring systems such as drag embedment anchors and vertically loaded anchors are used to keep these units in place. Past mooring system failures due to hurricanes in 2004 and 2005 initiated a need to better understand the performance of these anchors to in-plane and out-of-plane loading conditions. In-plane and out-of-plane loading cause the anchor to translate or rotate in the directions of its six degrees of freedom. Behavior and holding capacity of the anchors when loaded in each of is six degrees of freedom are important in understanding and predicting their behavior. An experimental program was devised to investigate the behavior of anchors in pure translation and rotation loading. The scaled-model anchors were embedded at a measured depth in a soil bed of clay with an undrained shear strength between 10 and 20 psf and then loaded to failure. A rotation testing frame was designed to impose rotational loading in the yaw, roll and pitch directions. Test results from the experimental program are consistent and repeatable. The bearing factors for pure bearing fell well within the range of existing experimental and analytical studies on simple plates. Bearing factors for in-plane and out-of-plane shear and for all rotations are higher than those for simple plates due to presence of the shank. When the resistance is normalized by area of the fluke, the wider model provide greater normalized resistance to yawing, similar normalized resistance to pitching and rolling and less normalized resistance to bearing and shearing. It was concluded that the holding capacity of an anchor in its six degrees of freedom depends largely on its geometry, including the fluke and the shank. / text

京都大学 / 0048 / 新制・課程博士 / 博士(地球環境学) / 甲第17802号 / 地環博第109号 / 新制||地環||22(附属図書館) / 30609 / 京都大学大学院地球環境学舎地球環境学専攻 / (主査)教授 勝見 武, 教授 三村 衛, 准教授 乾 徹 / 学位規則第4条第1項該当 / Doctor of Global Environmental Studies / Kyoto University / DFAM

This thesis evaluates the commonly used geotechnical probing method CPTu, on how different probe configurations impact the resulting evaluated undrained shear strength in soft clay deposits, in comparison to each other and laboratory methods. This is done by performing field investigations on Lindefältet, Södermanlands län, Sweden. Comparison is done on the two Swedish manufacturers of CPTu probes, by different calibration limits, filter types and whether overloading the probe over the calibration limit affects the evaluated undrained shear strength registered. The main conclusions are that one of the manufacturers’ probes registers deviating results in one configuration, that calibration limit has a noticable impact on the results, and that overloading on the probe and filter choice has negliable impact on the results. / I detta examensarbete utvärderas den vanligt förekommande geotekniska sonderingsmetoden CPTu, på hur olika konfigurationer av sonder påverkar den resulterande utvärderade odränerade skjuvhållfastheten i lösa leravlagringar, 9i jämförelse med varandra och med laboratoriemetoder. Detta är genomfört genom fältundersökningar på Lindefältet, Södermanlands län. Jämförelsen gjordes på de två svenska CPTu-tillverkarnas sonder. Detta är gjort med hänsyn till olika kalibreringar av konspetstryck, filtertyper, och huruvida sonden har varit överlastad påverkar den utvärderade skjuvhållfastheten som registreras. De huvudsakliga slutsatserna är att en av tillverkarnas sonder registerar udda värden i en konfiguration, att kalibreringar av konspetstryck har en märkbar påverkan på de resulterande värdena på utvärderade odränerade skjuvhållfastheten, samt att överlastning av sonder och val av filtertyp har liten till omärkbar påverkan på resultatet.

Anisotropy in engineering properties of soils occurs due to the depositional process forming the soil fabric and/or different directional stresses in soil history. This study investigates the anisotropy in undrained shear strength and drained compressibility of preconsolidated, stiff and fissured Ankara Clay. The compressibility behavior is determined using standard oedometer testing while the shear strength anisotropy is investigated through large diameter unconsolidated-undrained triaxial testing on undisturbed samples taken in vertical and horizontal directions from several deep excavation sites along the Konya Road in &Ccedil / ukurambar-Balgat Area, Ankara. According to the results achieved, Ankara Clay is slightly anisotropic in compressibility, with an anisotropy ratio between 0.72 and 1.17 in terms of coefficient of volume compressibility for several pressure ranges between 50 kPa and 1600 kPa. On the other hand, while a slight anisotropy in undrained shear strength at a ratio ranging between 0.87 and 1.19 in terms of deviator stress can be observed in Ankara Clay, considering the great variation in the test results of samples in same direction which mostly overlaps with the range of results obtained in the other direction, it has been concluded that the Ankara Clay located in this area can be regarded as isotropic in terms of shear strength for practical purposes.

ABSTRACT SHEAR STRENGTH BEHAVIOUR OF SAND - CLAY MIXTURES &Ouml / LMEZ, Mehmet Salih M.S., Department of Civil Engineering Supervisor: Prof. Dr. Mehmet Ufuk ERGUN May 2008, 106 pages A clean sand having about 5 % fines has been mixed with 5 to 40 % commercial kaolin to form different sand-clay soil mixtures. The purpose of making this study is to observe the effects of fraction of fine materials in the soil mixture on the behavior of shear strength. Three series of experiments have been performed throughout the study. Undrained triaxial compression tests (series 1) are performed on specimens taken out from homogeneously mixed soil mixtures at specified kaolin contents consolidated in a box without keeping the mixture under water. In series 2 experiments specimens are taken from a box where soil mixtures are consolidated under water and undrained triaxial compression tests are performed on the samples. Drained direct shear tests are performed on samples prepared without performing initial consolidation in large boxes but directly prepared in the direct shear boxes and consolidated prior to shear (series 3). It has been found that about 20 % kaolin - 80 % sand mixture seems to be a threshold composition and changes in both undrained and drained shear stress-strength behaviour occur afterwards with increasing fine material content.

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.