193 research outputs found

    A simulation-based software to support the real-time operational parameters selection of tunnel boring machines

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    With the fact that the main operational parameters of the construction process in mechanized tunneling are currently selected based on monitoring data and engineering experience without exploiting the advantages of computer methods, the focus of this work is to develop a simulation-based real-time assistant system to support the selection of operational parameters. The choice of an appropriate set of these parameters (i.e., the face support pressure, the grouting pressure, and the advance speed) during the operation of tunnel boring machines (TBM) is determined by evaluating different tunneling-induced soil-structure interactions such as the surface settlement, the associated risks on existing structures and the tunnel lining behavior. To evaluate soil-structure behavior, an advanced process-oriented numerical simulation model based on the finite cell method is utilized. To enable the real-time prediction capability of the simulation model for a practical application during the advancement of TBMs, surrogate models based on the Proper Orthogonal Decomposition and Radial Basis Functions (POD-RBF) are adopted. The proposed approach is demonstrated through several synthetic numerical examples inspired by the data of real tunnel projects. The developed methods are integrated into a user-friendly application called SMART to serve as a support platform for tunnel engineers at construction sites. Corresponding to each user adjustment of the input parameters, i.e., each TBM driving scenario, approximately two million outputs of soil-structure interactions are quickly predicted and visualized in seconds, which can provide the site engineers with a rough estimation of the impacts of the chosen scenario on structural responses of the tunnel and above ground structures

    Numerical simulation of ground movements and structural forces in lining for Earth Pressure Balance (EPB) tunneling in clay

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    Thesis (S.M.)--Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2013.Cataloged from PDF version of thesis.Includes bibliographical references (pages 129-133).This thesis describes the development of a 3D finite element model for representing mechanized tunnel construction using an Earth Pressure Balance (EPB) machine in clay. The model uses the commercial FE code, Plaxis 3D, to represent the face pressure, conical shield, grouting process and activation of precast segmental concrete lining systems through a set of boundary conditions that advance through the soil mass along a prescribed trajectory. The model simulates ground conditions associated with on-going EPB tunnel construction for the Crossrail project in central London. The analyses use a linearly-elastic perfectly plastic (MC) soil model based on design profiles of undrained shear strength and stiffness characteristics of London Clay. The analyses show the importance of the in situ Ko-effective stress conditions on predictions of the free-field, short-term (i.e., undrained) ground movements caused by tunnel construction as well as the structural forces induced in the segmental lining. The results of the model are in good overall agreement with simulations from a more complex finite element model that uses sub-structing to represent the EPB machine (Kratos-ekate program; done in collaboration with the research group at TU Bochum). The results of this study form the basis for more extensive research on time dependent ground response and interactions with overlying structures.by Vasiliki Founta.S.M

    From digital models to numerical analysis for mechanised tunnelling: a fully automated design-through-analysis workflow

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    Large infrastructure projects involving the construction of tunnels in urban areas constitute complex, integrated and multi-disciplinary systems, which require building and construction information modelling as well as computational design assessment tools for decision making during all project phases and during their complete life cycle. Even if the underlying information needed for computational analysis is stored in an information model, the translation to computational models is still cumbersome and requires significant manual work for model generation and set-up as well as excessive computing resources and time. To address these shortcomings, this paper presents a systematic summary of concepts for integrated information modelling, numerical analysis and visualisation for urban mechanized tunnelling. Our first approach “BIM-to-FEM” is characterised by a fully automated link for error-free data exchange between a standalone Tunnelling Information Model and the process-oriented simulation model for mechanized tunnelling “ekate”. In the second approach “SATBIM”, a fully automated data exchange workflow is established between a parametric multi-level information model for tunnelling and multi-level numerical models based on both Finite Element and Isogeometric Analysis, where meta models are employed for real-time design assessment. We discuss the different applications of these concepts, such as scenario-based exploration of design alternatives, real-time design assessment within a TIM based on meta-models, and the potentials of using these models for the process control during construction. Furthermore, we present two case studies where real project data has been used for the integration of information and numerical modelling. The examples in this paper indicate clear advantages of this approach compared to traditional approaches in terms of efficiency of modelling achieved by reduced user interactions and error-free information exchange, and show the benefits of multi-level model representation and real-time analysis tasks

    Advanced Underground Space Technology

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    The recent development of underground space technology makes underground space a potential and feasible solution to climate change, energy shortages, the growing population, and the demands on urban space. Advances in material science, information technology, and computer science incorporating traditional geotechnical engineering have been extensively applied to sustainable and resilient underground space applications. The aim of this Special Issue, entitled “Advanced Underground Space Technology”, is to gather original fundamental and applied research related to the design, construction, and maintenance of underground space

    Advanced Theoretical and Computational Methods for Complex Materials and Structures

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    The broad use of composite materials and shell structural members with complex geometries in technologies related to various branches of engineering has gained increased attention from scientists and engineers for the development of even more refined approaches and investigation of their mechanical behavior. It is well known that composite materials are able to provide higher values of strength stiffness, and thermal properties, together with conferring reduced weight, which can affect the mechanical behavior of beams, plates, and shells, in terms of static response, vibrations, and buckling loads. At the same time, enhanced structures made of composite materials can feature internal length scales and non-local behaviors, with great sensitivity to different staking sequences, ply orientations, agglomeration of nanoparticles, volume fractions of constituents, and porosity levels, among others. In addition to fiber-reinforced composites and laminates, increased attention has been paid in literature to the study of innovative components such as functionally graded materials (FGMs), carbon nanotubes (CNTs), graphene nanoplatelets, and smart constituents. Some examples of smart applications involve large stroke smart actuators, piezoelectric sensors, shape memory alloys, magnetostrictive and electrostrictive materials, as well as auxetic components and angle-tow laminates. These constituents can be included in the lamination schemes of smart structures to control and monitor the vibrational behavior or the static deflection of several composites. The development of advanced theoretical and computational models for composite materials and structures is a subject of active research and this is explored here for different complex systems, including their static, dynamic, and buckling responses; fracture mechanics at different scales; the adhesion, cohesion, and delamination of materials and interfaces

    Back analysis of intensive rock mass damage at the El Teniente mine

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    A three dimensional non-linear solution of stress, strain and energy distribution was developed to determine the deformation and damage on the extraction level and undercut level for comparison with observations during model calibration. Based on the plastic strain results (% rock mass damage), an Esmeralda scale damage was developed for its extraction evolution. By mean of this scale, the collapsed zones by periods were assessed in order to undertake the final phase of back analysis

    Mining Safety and Sustainability I

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    Safety and sustainability are becoming ever bigger challenges for the mining industry with the increasing depth of mining. It is of great significance to reduce the disaster risk of mining accidents, enhance the safety of mining operations, and improve the efficiency and sustainability of development of mineral resource. This book provides a platform to present new research and recent advances in the safety and sustainability of mining. More specifically, Mining Safety and Sustainability presents recent theoretical and experimental studies with a focus on safety mining, green mining, intelligent mining and mines, sustainable development, risk management of mines, ecological restoration of mines, mining methods and technologies, and damage monitoring and prediction. It will be further helpful to provide theoretical support and technical support for guiding the normative, green, safe, and sustainable development of the mining industry

    Measurement and prediction of dilution in a gold mine operating with open stoping mining methods

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    Mining worldwide and definitely in South Africa, is constantly under pressure to reduce its cost structure to sustain profitability. In underground gold mines where an open stope mining method is employed, dilution often has a significant effect on the viability of sustaining profits. Target Mine practices the Open Stope mining Method and it was found that in some open stopes dilution was in excess of 10%, which has a significant impact on the sustainability of the mine

    Sayısal ve ampirik analizler yardımıyla ikiz tünel kaynaklı zemin deformasyonlarının değerlendirilmesi (Avrasya tüneli, NATM kısmı, İstanbul, Türkiye).

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    Pre-support systems become very important for inner-city shallow tunnels especially while applying New Austrian Tunneling Method (NATM) which requires some deformation to relieve the stress. Previous studies about assessing the magnitude of surface displacements caused by twin tunneling do not include the effects of presupport system and stress release by deformation. Moreover, most of the established empirical equations were obtained by using data from tunnel passing through clayey soil. Objective of this thesis is to introduce a detailed procedure for obtaining modification factor including the effects of pre-support system and of rock mass quality and which can be used as a reduction ratio in prediction methods used for twin tunnel induced surface settlement. Twin tunnel induced surface settlement data comes from Asian side of the Eurasia Tunnel excavated by using NATM method and supported by forepoling and umbrella arch method. The steps that need to be completed in order to achieve the determined objective are; i) performing numerical analysis on the selected 12 cross section lines along tunnel route to update the geological profile at which there is no borehole drilled and to approximate the results of numerical models to actual field measurement in terms of maximum surface settlement, ii) conducting parameter study in which the distance between pipes in the pre-support systems was used as a variable, iii) obtaining a statistical formula that presents the decreasing effect of pre-support system on maximum surface settlement. It was concluded that twin tunnel-induced surface settlement mainly depends on deformation modulus of the geo-materials around tunnel. Deformation modulus was obtained by evaluating rock mass quality which is controlled by fracturing and surface weathering. A new formula predicting twin tunnel induced ground deformation is proposed as a modification factor of Herzog’s equation.Ph.D. - Doctoral Progra

    Mechanical behaviour of conditioned material for EPBS tunnelling

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    The rapid growth of the development of the cities all over the World, brought the necessity of bringing deeper the services and all the activities which are not strictly necessary above the ground like houses. This sudden demand of new tunnels obliged to push the excavation industry towards mechanized methods which allow to avoid settlements on the surface, where other structures and infrastructures are located. In this context EPB shield machines play a crucial role, as with a good control of this technology, a tunnel can be excavated basically everywhere, also below important structures. This implies the perfect knowledge of the geology but especially requires a precise study of the soil conditioning, in order to allow an effective counterpressure to the front. The development of preliminary laboratory tests, which means before the tunnel project starts, allows to assess the best conditioning set for each lithotype which can be encountered during the excavation. These tests are performed at room pressure, nevertheless recently the main goal is to study the conditioned mass at pressure conditions which can be found in an excavating chamber, which might influence the state of the mass itself. The aim of this work is the development of new techniques which can exactly reproduce this state, through the use and modification of techniques proper of the geotechnical engineering (shear and triaxial tests) and the design of new devices able to underline these aspects in detail. The new approach includes, as well as the consideration of a certain pressure condition, also the definition of an undrained condition used for testing, which allows to keep the conditioned mass in its original state for its study
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