Geotechnical design of railway embankments – requirements and challenges

Intensive development of railway infrastructure in Poland is associated with significant support provided for that purpose by the European Union, especially, by investments in the modernization of existing railway lines. Together with the improvement of the infrastructure in less developed countries, an interoperability of rail system at the international level is sought through the technical harmonization, mostly by the introduction of European regulations and technical standards. The paper presents the main requirements associated with the geotechnical aspects of design of railway embankments, mostly relating to their overall stability and maintenance of serviceability. Some aspects of the European standards as well as international, national, and internal regulations, are discusses in the context of challenges encountered by designers. The main geotechnical issues are associated with safety requirements, loading conditions, geometry of railway embankments, as well as the scope of geotechnical investigation necessary to make an informed decision on a final design solution

Electric power industry structures in light of upcoming 2nd generation of Eurocodes

Budownictwo w sektorze energetycznym często związane jest ze znacznie większymi potencjalnymi konsekwencjami zniszczenia i potrzebą zachowania użytkowalności obiektów. Wynika to z potrzeby zapewnienia niezawodności systemu, a nie tylko jego poszczególnych elementów. W tym kontekście przedstawiono i omówiono nadchodzące zmiany w drugiej generacji europejskich norm dotyczących projektowania konstrukcji (Eurokodów). Najważniejsza ze zmian, wprowadzenie zróżnicowania poziomu niezawodności, została omówiona w kontekście jej wpływu na projektowanie z wykorzystaniem współczynników częściowych i zaproponowanego systemu zarządzania jakością. Na koniec omówiono niektóre ze zmian w normie Eurokod 7 Projektowanie geotechniczne, gdyż ta norma została poddana największym modyfikacjom.Civil engineering in the power industry is often associated with much higher potential consequences of failure as well as the need for maintaining serviceability. It stems from the need of ensuring the reliability for the system rather than only its parts. In this context, upcoming changes in the second generation of European structural design codes (Eurocodes) are presented and discussed. The most important one, reliability differentiation, is discussed in the context of its impact on the design using partial factors as well as the implementation of the quality management system. In the end, some additional changes in Eurocode 7 “Geotechnical design” are discussed, as this standard is undergoing the most significant evolution

Preliminary assessment of variability of selected Hardening Soil model parameters for glacial tills and clays from Poland

Typical ranges of variability of basic soil parameters are relatively well known. Such knowledge is important to aid engineers in the selection of characteristic values for design or as a basis for conducting sensitivity analyses for more complex soil-structure interaction problems. However, for application of advanced non-linear constitutive models, which often are defined by model-specific parameters, such variability is rarely known. To improve parameter estimation, as well as to provide a basis for the choice of realistic variability range, a database of high quality laboratory tests can be used. The paper presents the results of preliminary assessment of variability of selected Hardening Soils model parameters for overconsolidated glacial tills and clays from Poland, based on a local database of triaxial test results

Geotechnical design of railway embankments – requirements and challenges

Intensive development of railway infrastructure in Poland is associated with significant support provided for that purpose by the European Union, especially, by investments in the modernization of existing railway lines. Together with the improvement of the infrastructure in less developed countries, an interoperability of rail system at the international level is sought through the technical harmonization, mostly by the introduction of European regulations and technical standards. The paper presents the main requirements associated with the geotechnical aspects of design of railway embankments, mostly relating to their overall stability and maintenance of serviceability. Some aspects of the European standards as well as international, national, and internal regulations, are discusses in the context of challenges encountered by designers. The main geotechnical issues are associated with safety requirements, loading conditions, geometry of railway embankments, as well as the scope of geotechnical investigation necessary to make an informed decision on a final design solution

Change in groundwater conditions as a cause of structural failure – selected case studies

The paper presents the summary of five case studies related to structural failures that were caused by the change in groundwater conditions during the existence of the buildings. The failures resulted from excessive differential settlements that were caused either by reactivation of consolidation process, due to change in effective stresses, or a change in water content in the case of expansive soils

Parametry stosowane przy ocenie niecki osiadań wywołanej drążeniem tuneli tarczami TBM

One of major design problems associated with shallow tunnelling in urbanized areas is the prediction of ground displacements caused by the construction process. Advanced tunnelling techniques such as shield tunnelling using Earth Pressure Balance Tunnel Boring Machines (EPB-TBMs) allow for significant reductions of settlements observed at the ground surface in comparison to tunnelling methods used in the past. The predictions of these displacements are often based on semi-empirical methods and prior experience. In addition to relative simplicity of such methods, their robustness and decades of validation in many tunnelling projects make them attractive for practical use. The tunnelling-induced settlement trough at the ground surface can be described by inversed Gaussian distribution function. It requires only the assumption of two parameters, namely: expected volume loss (VL) and the distance to the point of inflection (iy ), which is dependent on the empirical trough width parameter (K) and the tunnelling depth (z0). The values of those parameters have a strongly empirical nature; they should be established based on comparable experience obtained from full scale tunnelling projects with similar technique and at similar ground conditions. The paper presents the problem of variability of those parameters and discusses the need for its assessment. As volume loss is strongly related to the tunnelling technique, the study focuses on EPB-TBM tunnelling as the most commonly implemented one in recent years. Variability of parameters observed for different ground conditions in different countries is summarized. Finally, preliminary assessment of variability of settlements observed in Warsaw region is presented.Jednym z głównych wyzwań związanych z projektowaniem płytko posadowionych tuneli na terenach zurbanizowanych jest predykcja deformacji podłoża wywołana procesem ich drążenia. Zaawansowane techniki realizacje takie jak zastosowanie tarcz zmechanizowanych TBM typu EPB pozwala na znaczną redukcję osiadań obserwowanych na powierzchni terenu, w porównaniu do technik stosowanych w przeszłości. Przewidywanie tych przemieszczeń jest oparte głównie o stosowanie modeli pół-empirycznych oraz wcześniejsze doświadczenia porównywalne. Poza samą prostotą tych metod, dekady ich stosowania w projektowaniu tuneli stanowią wystarczającą walidację skłaniającą projektantów do ich wyboru w analizach projektowych. W podejściu pół-empirycznym, niecka osiadania na powierzchni terenu wywołana tunelowaniem jest opisywana odwróconą funkcją rozkładu normalnego Gaussa. Wymaga to jedynie przyjęcia założeń odnośnie dwóch parametrów, mianowicie: spodziewanej utraty objętości (VL) oraz odległości do punktu przegięcia (iy), która zależy od empirycznego parametru charakteryzującego szerokość niecki (K) oraz głębokości tunelu (z0). Parametry te mają charakter silnie empiryczny i powinny być przyjmowane w oparciu o doświadczenia porównywalne uzyskane w skali rzeczywistej przy realizacji tuneli w danej technologii i podobnych warunkach gruntowych. Niniejszy artykuł przedstawia problem zmienności wyżej wymienionych parametrów oraz rozważa potrzebę ich dokładniejszej oceny. Ponieważ utrata objętości jest silnie związana z technologią realizacji tunelu, praca koncentruje się na technologii EPB-TBM, jako najpowszechniej stosowanej w ostatnich latach. Przedstawiono podsumowanie zmienności parametrów obserwowanych dla różnych warunków gruntowych w różnych krajach. Na koniec, przedstawiono również wstępną ocenę zmienności osiadań obserwowanych dla obszaru Warszawy

Analiza posadowienia fundamentu pierścieniowego chłodni kominowej

Artykuł prezentuje analizę posadowienia oraz wytyczne do projektu konstrukcji chłodni kominowej w elektrowni konwencjonalnej. Zaprezentowano ogólną charakterystykę konstrukcji, główne założenia projektowe oraz opis warunków gruntowo-wodnych na rozpatrywanym obszarze. Następnie omówiono zakres i główne założenia analizy. Otrzymane na podstawie analizy wyniki prezentują podsumowanie rozważań projektowych związanych z wyborem ostatecznie przyjętego sposobu posadowienia. Ostatecznie uzyskano zoptymalizowany rozkład współczynnika podatności sprężystej podłoża, wraz z przewidywanymi wartościami osiadań po obwodzie fundamentu chłodni kominowej.The paper presents an analysis regarding the foundation solution as well as provided guidance for structural calculations for a cooling tower of a conventional coal-fired power plant. The characteristic of the structure, its main design assumptions, and description of ground conditions at the site are briefly presented. Then, the scope and main assumptions of the analysis are described. Presented results, based on this analysis, show the summary of design consideration for the optimal foundation solution chosen in the end. Finally, the optimized distribution of modulus of subgrade reaction was obtained, together with predicted settlement, along the circumference of the cooling tower’s foundation

Preliminary back-analysis of the height of mud brick fortifications based on geoarchaeological data at tell El-Retaba site in Egypt

The Tell el-Retaba archaeological site is located at Wadi Tumilat, a shallow valley running from the Nile Delta to the Bitter Lakes. In ancient times, a route connecting Egypt with Syria-Palestine ran across the site. In the 13th century BC, during the rule of Ramesses II, a fortress surrounded by “Wall 1” was erected and in times of Ramesses III in the 12th century BC, a larger fortress surrounded by “Wall 2” and “Wall 3” was constructed. Using the finite element method (FEM) and ZSoil 2D&3D software, the wall heights were modelled and their soil-structure interaction was analysed. Strength of the wall depended on size and strength of bricks and mortar, brickwork, wall shape and foundation. Ancient builders using mud bricks must have known from practical experience the essentials of a wall construction, in which the height to width ratio was at 1.75 to 1.85. Moreover, they must have related the engineering properties of the material with the height of the construction and its purpose. The width to height ratio must have been used and related by ancient Egyptians to the ground resistance. Modelling has shown that, at wall width of 5 m, the foundation would have lost its stability at wall height of 13–14 m and bricks from the lower part of the wall would be destroyed. According to the undertaken assumptions, in order to retain stability, the wall height must have been limited to about 8–9 m