In first part of the thesis are proposed four variants of retaining structures for deep excavation of cut-and-cover tunnel part. It is nailed slope, pile wall, nailed slope in combination with pile wall and soldier pile wall. For those structures is in following part carried out an economic analysis and the most cost effective variant is chosen. Chosen structure is further analyzed in next part. This analysis is carried out with finite element method in software PLAXIS. As a material model is chosen Hardening Soil model and input parameters were determined by empiric formulas from literature. Behavior of neogene clays, in which is the structure designed, is considered as undrained, by type Undrained A. In the last part of the thesis is described technological procedure of construction this retaining structure.

Foundations on unbearable and yielding subsoil require such actions as to achieve both desired bearing capacity and limited settlement. Issue is presented at foundation the circular tank in saturated fine-grained soils, circular tank in Klobouky u Brna in particular. Comparison analysis is performed for alternative methods (shallow foundation, vibro stone columns, deep soil mixing, pile foundation). Differential and total settlement, time-depending analysis and baseplate stress state (bending moment, shear force) are assessed for each alternative. Pile foundation provides the best results regarding total and differential settlement, but baseplate is also under high puncture shear stress. Vibro stone columns seem suitable due to time-depending analysis of settlement, on the other hand settlement reductions are not just as good. Deep soil mixing provides satisfactory alternative for both pile foundation and vibro stone columns. Under such circumstances shallow foundation is not suitable.

Les opérations de dragage génèrent d’importants volumes de sédiments à teneur en eau élevée qui sont difficilement transportables. Toute opération de valorisation ou stockage des sédiments implique de réduire la teneur en eau. Le séchage naturel et la déshydratation mécanisée des sédiments répondent à cette attente. Le séchage naturel des sédiments est la technique de déshydratation la plus économique et la meilleure du point de vue environnemental. Le temps de séchage peut être réduit par des moyens techniques adaptés (retournement, scarification) mis en action par l'application de critères d’aptitude au séchage naturel. Pour ce faire, le processus de séchage naturel a été reproduit à l’échelle du laboratoire à l’aide d’essais d’Égouttage et de Séchage et d’essais de Séchage et de Retrait couplés à des essais scissométriques. Ils ont porté sur neuf sédiments : sept sédiments de barrage, deux sédiments marins et une kaolinite. Une relation Su=f(IP) a été établie. Cette relation permet d’obtenir la cohésion non drainée Su à partir d’une mesure de teneur en eau. Elle permet aussi de définir ou cerner le moment le plus propice au retournement des sédiments à l’aide d’engins spécifiques sur site. Une autre méthode mécanique pour réduire le temps de séchage est suggérée. Il s'agit de pratiquer une scarification des sédiments à l’aide d’outils mobiles, voire robotisés, comme un rouleau scarificateur ou d'une rangée d'outils transportés par un treillis mobile adapté. En ce qui concerne la déshydratation mécanisée des sédiments, une nouvelle méthode de déshydratation en continu a été proposée à partir d'une presse à boues KDS®. Pour des raisons de conception et d'application, la presse à boues KDS® n’a jamais été utilisée pour déshydrater des sédiments. Un plan expérimental a été développé. Il est démontré que la presse KDS® est capable de déshydrater un sédiment fin sableux sans une maintenance démesurée. Des adaptations de la presse KDS® à la déshydratation de sédiments et des améliorations sont finalement proposées. / Dredging operations produce large amounts of sediments with high water content, that are difficult to handle. Storage management and future reuses need to reduce the water content of sediments. Natural and mechanical dewatering of sediments meet this need. The most economic and eco-friendly method of dewatering is natural dewatering. Dewatering period can be reduced with suitable technical means such as adapted plough or scarifier for sediments, operating under defined dewatering criteria. The natural dewatering process was investigated and reproduced at the laboratory scale by performing Natural dewatering test and Shrinkage test coupled with shear measurements (vane shear testing). Nine sediments have been considered: seven dam sediments, two marine sediments and a kaolinite clay. A relationship Su = f(IP) has been established. It allows to deduce the undrained shear strength Su from only a measurement of water content. It allows to state on the right moment to put in operation the specific tools for ploughing and returning over or scarifying sediments stored. These tools can move in the sediments (adapted plough) or roll on the sediments (scarifiying roller) or roll on banks of sediment storage basin. Another way to dewater high water content sediments concerns a mechanical device. Thus a new method of continuous dewatering has been investigated using a prototype machine patented and referenced as KDS® sludge press. This type of press was not adapted for dewater sediments. Full of dewatering tests have been undertaken and performed with this prototype concerning some of sediments (see natural dewatering testing) and sandy clayey mixtures. It has been shown that KDS® press is able to dehydrate sediments including fine sandy sediments without excessive maintenance. Some adaptations and improvements of KDS® press to dewatering sediments are finally suggested.

The undrained shear strength and preconsolidation pressure are key parameters in describing the characteristics of soft clays. The two parameters both reflect the clay’s structure and state of stress, and hence empirical correlations for undrained shear strength normalized with respect to preconsolidation pressure are widely used to assess soil behavior. The empirical correlations given in the literature are typically dependent on liquid limit, or plasticity index, but some studies have questioned the dependency and proposed correlations constant for consistency limits. Data from geotechnical projects often display a considerable scatter and deviate from established empirical correlations. In this thesis, statistical analyses are performed and evaluated qualitatively on direct simple shear, constant rate of strain and fall cone test data from 146 sampling points with a total of 596 soil samples from Stockholm, Gothenburg and Uppsala. The aim is to investigate the correlation between shear strength and the preconsolidation pressure. The thesis evaluates the normalized shear strength’s dependency on liquid limit, how the data corresponds to Hansbo’s (1957) and Swedish Geotechnical Institute’s (2007) linear empirical correlations, and the correction factor applied to shear strength measured by the fall cone test. The results of the study show that the correction factor typically reduces the shear strength from fall cone tests too much with respect to shear strength from direct simple shear tests. The normalized shear strength’s dependency on liquid limit may be rejected for the fall cone test data. The results for direct simple shear test data however, indicates a correlation with liquid limit. The data scatter is considerable, especially for fall cone test data, and the relevance of describing the normalized shear strength from fall cone test with a linear empirical correlation to liquid limit may conclusively be questioned. / Skjuvhållfasthet och förkonsolideringstryck är två viktiga jordparametrar för lösa leror. Båda parametrar reflekterar lerans struktur och spänningstillstånd, och empiriska korrelationer för odränerad skjuvhållfasthet, normaliserad mot förkonsolideringstrycket, används därför ofta för att bedöma en leras egenskaper. De empiriska korrelationerna är vanligen kopplade till flytgräns eller plasticitetsindex. Dessa korrelationer har däremot ifrågasatts av studier som i vissa fall istället föreslagit ett konstant förhållande mellan normaliserad odränerad skjuvhållfasthet och plasticitetsgränser. Mätvärden från geotekniska projekt i Sverige visar allmänt stor spridning avseende dessa parametrar och data avviker ofta från etablerade empiriska korrelationer. I examensarbetet har data från direkta skjuvförsök, ödometerförsök och fallkonförsök utvärderats statistiskt och kvalitativt. Totalt omfattar studien 596 jordprover från 146 provtagningspunkter från Stockholm, Göteborg och Uppsala. Syftet med studien är att undersöka korrelationen mellan odränerad skjuvhållfasthet och förkonsolideringstryck. Studien behandlar den normaliserade skjuvhållfashetens flytgränsberoende, Hansbos (1957) och Statens Geotekniska Instituts (2007) empiriska korrelationer, samt den korrektionsfaktor som ska tillämpas på skjuvhållfastheter från fallkonförsök. Resultatet visar att korrektionsfaktorn reducerar skjuvhållfastheten för mycket och att korrigerade skjuvhållfastheter är i sämre samstämmighet med skjuvhållfastheter från direkta skjuvförsök än okorrigerade. Data från fallkonförsök uppvisar inget tydligt flytgränsberoende, medan resultaten från direkta skjuvförsök indikerar ett beroende. Spridningen i data är dock påfallande, särskilt för fallkonförsöket. Relevansen i att tillämpa en linjär empirisk korrelation för odränerad normaliserad från fallkonförsök mot förkonsolideringstryck beroende av flytgräns bör ifrågasättas.