160,621 research outputs found
Development of an earthquake simulator for soft soils: Multidirectional Shear Testing Device
No full textTesting soils for earthquake and dynamic loads requires advanced equipment able to
assess the effects of hydromechanical coupling on the soil response. The majority of laboratory
element tests are either “slow tests”, which intend to approach drained conditions throughout the
soil sample in order to obtain reliable pore water pressure measurements, or “fast undrained
tests”, where flow is prevented by closing the drainage lines. However, many natural loads,
including earthquakes, impose a wide range of high loading frequencies, typically triggering a
partially drained response in the field. Although the rate effect plays an important role in soil
behaviour, its investigation is hindered by the limitations of existing equipment. In addition, the
ability to apply multidirectional loading to soil elements in the laboratory is important to fully
understand the soil response under earthquakes. Currently, multidirectional simple shear devices
are used to study the soil behaviour under earthquake loadings. Nevertheless, many shear devices
suffer from stresses and strains non-uniformities, which could potentially mislead data
interpretation and constitutive models development. This paper presents an innovative
multidirectional shear device developed in the section of Geoengineering at TU Delft, which can
apply higher loading frequencies compared to previous equipment and a wider variety of
multidirectional cyclic loading patterns. The apparatus is equipped with advanced sensors, also
developed at TU Delft, to capture the local response of specimens. The sensors are installed to
reduce a priori assumptions on the soil response, better interpret the element experimental results
and further investigate the rate effect of applied loading. Preliminary performance test results are
provided to illustrate the complex load conditions which can be achieved
Underground space utilisation for urban renewal
No full textThe rapid increase in world population in the 21st century, with associated transport and environmental problems, has encouraged the development of urban underground spaces as an optimal solution in many occasions, including urban renewal schemes. This paper reviews literature on the utilisation of urban underground space for urban renewal to provide a better understanding of how urban underground space can contribute to urban renewal, and of challenges and successes in achieving the goals. The paper concludes that urban underground space present new development opportunities (e.g. land/space supply, less traffic congestion, compact city development, and urban sustainable development) in regeneration of existing urban land. Urban underground spaces, as valuable resources and efficient and effective tools for urban renewal, should be considered by decision-makers for transforming existing urban areas, stimulating vibrant and denser development and mixed land use.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Geo-engineerin
Metro systems and urban development: Impacts and implications
No full textMany cities in the world have developed metro systems. Metro systems affect urban development in many ways, such as enhancing labour force mobility, increasing urban productivity and promoting urban underground space (UUS) utilisation to accommodate urban functions. This paper explores the relationship between metro systems and urban development, with particular focus on the comprehensive impacts of metro development on the economic, environmental and social development of cities. The contribution of metro systems to urban development has been confirmed by numerous studies in many cities in the world. The positive capitalisation of metro systems is reflected in property values in areas surrounding metro systems, although the impacts may vary spatially, temporally and geographically. In addition, metro systems impact on the natural and built environments by reducing air pollution and greenhouse gas emissions, encouraging new development and urban renewal, sharping urban development and land use, facilitating commercial growth and residential development, promoting the utilisation of UUS, and increasing mixed land use and urban density. However, there are mixed effects, both positive and negative, of metro systems on equality of transit opportunity, accessibility and connectivity, public health, travel behaviour, personal identity, travel experience and safety. This study sheds light on the impacts of metro systems on urban development, and provides important information for urban and transport planners and policy-makers wishing to develop metro systems to support sustainable urban development.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Geo-engineerin
Concrete Flow in Diaphragm Wall Panels: A Full-Scale In-Situ Test
No full textFlow processes, taking place during the concreting of diaphragm wall panels (D-wall panels), are of great importance for the quality of the wall. During this phase, the bentonite, present in the excavated trench, should be completely replaced by concrete in a controlled way. In literature several cases are described in which this process resulted in bentonite inclusions in the panel. These inclusions often lead to severe problems, like leakages, for the building pit to be excavated within the diaphragm wall panels. Beside the risks for the building pit, leakages caused by bentonite inclusions can also have large consequences for nearby constructions. In this article, set up and results of a full-scale diaphragm wall test are described. Conclusions are drawn with regard to the influence of several parameters on the flow process and subsequently on the quality of the wall and the risk on bentonite inclusions
Urban underground space: Solving the problems of today’s cities
No full textAbstractThe world-wide trend of increased urbanisation creates problems for expanding and newly-developing cities alike. Population increase leads to an increased demand for reliable infrastructure, nowadays combined with a need for increased energy efficiency and a higher environmental awareness of the public. The use of underground space can help cities meet these increased demands while remaining compact, or find the space needed to include new functions in an existing city landscape. In many cases, underground solutions to urban problems are only considered if all other (above ground) options have been exhausted. When underground solutions are considered and evaluated from the planning or initial project stages onwards, more optimal solutions will become possible.Use of the underground is not limited to large scale infrastructure projects. This paper also shows innovative use of the underground for commercial and residential use, storage, water conveyance and treatment, and heritage conservation, and highlights how use of underground can bring more optimal solutions for urban development
Special issue on building and infrastructure response to ground movement: Bridging the gap between geotechnical and structural modelling of SSI
No full textProf. Th. W. Adorno and the author Hans Erich Nossack.
No full textProf. Th. W. Adorno and the author Hans Erich Nossack at a reception of Insel Verlag, Buchmesse Frankfurt 1966LB
Face Stability Calculation for a Slurry Shield in Heterogeneous Soft Soils
No full textThe minimal support pressure needed at the tunnel face can be calculated using a wedge stability analysis. Current methods have been presented only for a homogeneous soil at the tunnel face. This Paper investigates the influence of heterogenity of the soil on the angle of slip and the minimal support pressure. It is found that the influence of horizontal layer boundaries is significant, especially at the top of the tunnel face. In case of a soft layer over a relatively stiff layer the minimal support pressure is greater than would be calculated by interpolation of the support pressures calculated for the separate layers.Accepted Author ManuscriptGeo-engineerin
On the Interaction between a Tunnel Boring Machine and the Surrounding Soil
No full textThe thesis investigates the mechanical equilibrium of a Tunnel Boring Machine (TBM) driving in soft soil. The interaction between the TBM-shield and the soil is also investigated. The analysis is based on monitoring data gathered during the construction of the Hubertus tunnel in The Hague, Netherlands. The monitoring activities during tunnel construction are discussed in detail. Special care is given to explain how the recorded data can be processed in order to verify a number of physical processes induced by the TBM-shield advance. TBM-data (machine data) and soil monitoring data (from inclinometers and extensometers) are examined. A kinematic model of TBM-shield behaviour is constructed from theoretical and geometrical considerations. The consequences of driving a TBM-shield in a curve are highlighted and validated against the TBM monitoring data. It is demonstrated how the kinematic model can provide the displacement history of the soil induced by the TBM-shield. Stresses, forces and moments acting on the TBM are covered in detail. Active and passive forces are combined and the equilibrium of the TBM-shield is considered by means of a purpose built numerical model. It is discussed which model features produce favourable conditions to the achievement of static equilibrium and which others may still hinder it. A quantitative assessment of the influence of the tail-void grouting is undertaken and uncertainties regarding the soil stiffness are discussed. It is observed that a considerable amount of the total tunnelling induced soil displacements occurs during the phase of temporary support. It is also demonstrated that the pattern of the induced displacements is more articulated than assumed in the volume-loss scheme.Geoscience & EngineeringCivil Engineering and Geoscience
Site effect affecting a runway in NAICM
No full textIn near future the Nuevo Aeropuerto Internacional de la Ciudad de México (NAICM) will be built in Mexico City. The airport’s construction is necessary as the Benitto Juarez Internatinal airport has reached its full capacity. The Mexico City area is notorious about its subsoil complexity and earthquake presence. Tunnel Engineer Company (TEC) has been assigned to provide seismic response advice. The importance of site amplification effects in seismic design of constructions is familiar by the up-to-date seismic design codes. Predominantly for constructions with high risk, founded in soft soil situations, site amplification effects are regarded as a significant factor that has to be considered in design. The TEC report provided vital insight on this topic, but basin effects were not included. This work aims to capture basin effects by simulating an elongated surface structure (runway) under earthquake loading, in one (1D) and two dimensional (2D) finite element environment. In the first part of the study a literature examination is conducted, thus to give an integral aspect of the project and especially in the runway characteristics. The hazard risk for NAICM as well as the seismic design requirements provided by TEC for runways is defined. The first part is concluded with a review of earthquake engineering investigation procedures and the background of site response analysis. The second part of the study is orientated to the calibration of the FEM model. The proper choice of clay parameters for the FEM model is a vital step so as to examine site response. Then, the emphasis is moved to free field dynamic analysis of soil column for vertically propagating shear waves because of its significance for seismic analysis of runways. Together linear and linear-elastic perfectly-plastic finite element modeling (FEM) are executed and compared to equivalent linear (E-L) frequency domain analysis. The conclusions extracted from this phase are significant input for the runway dynamic analysis, as they define the geotechnical parameters, the meshing size and the damping introduced in the system to generate valid outputs. Finally, the seismic runway response is presented. First is presented the construction stages and the changes in shear wave velocities, proposed by TEC, which are used to form a wised in place model for the airport’s runway. Comparison between 1D Linear and 2D FEM with linear soil material for one soil profile is examined as well as 1D E-L and 2D FEM Linear Elastic Perfectly Plastic (LE-PP), being followed by comparison between 1D E-L and 2D FEM LE-PP for different locations. Then the conclusions reached by this work are formed, continued by recommendations for possible future work.Civil Engineering and GeosciencesGeoscience & Engineerin
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