Real-time assessment of tunnelling-induced damage to structures within the building information modelling framework

During the initial design phases of complex multi-disciplinary systems such as urban tunnelling, the appraisal of different design alternatives can ensure optimal designs in terms of costs, construction time, and safety. To enable the evaluation of a large number of design scenarios and to find an optimal solution that minimises impact of tunnelling on existing structures, the design and assessment process must be efficient, yet provide a holistic view of soil-structure interaction effects. This paper proposes an integrated tunnel design tool for the initial design phases to predict the ground settlements induced by tunnelling and building damage using empirical and analytical solutions as well as simulation-based meta models. Furthermore, visualisation of ground settlements and building damage risk is enabled by integrating empirical and analytical models within our Building Information Modelling (BIM) framework for tunnelling. This approach allows for near real-time assessment of structural damage induced by settlements with consideration of soil-structure interaction and non-linear material behaviour. Furthermore, because this approach is implemented on a BIM platform for tunnelling, first, the design can be optimised directly in the design environment, thus eliminating errors in data exchange between designers and computational analysts. Secondly, the effect of tunnelling on existing structures can be effectively visualised within the BIM by producing risk-maps and visualising the scaled deformation field, which allows for a more intuitive understanding of design actions and for collaborative design. Having a fully parametric design model and real-time predictions therefore enables the assessment and visualisation of tunneling-induced damage for large tunnel sections and multiple structures in an effective and computationally efficient way

Reasonable mechanical model on shallow tunnel excavation to eliminate displacement singularity caused by unbalanced resultant

When considering initial stress field in geomaterial, nonzero resultant of shallow tunnel excavation exists, which produces logarithmic items in complex potentials, and would further lead to a unique displacement singularity at infinity to violate geo-engineering fact in real world. The mechanical and mathematical reasons of such a unique displacement singularity in the existing mechanical models are elaborated, and a new mechanical model is subsequently proposed to eliminate this singularity by constraining far-field ground surface displacement, and the original unbalanced resultant problem is converted into an equilibrium one with mixed boundary conditions. To solve stress and displacement in the new model, the analytic continuation is applied to transform the mixed boundary conditions into a homogenerous Riemann-Hilbert problem with extra constraints, which is then solved using an approximate and iterative method with good numerical stability. The Lanczos filtering is applied to the stress and displacement solution to reduce the Gibbs phenomena caused by abrupt change of the boundary conditions along ground surface. Several numerical cases are conducted to verify the proposed mechanical model and the results strongly validate that the proposed mechanical model successfully eliminates the displacement singularity caused by unbalanced resultant with good convergence and accuracy to obtain stress and displacement for shallow tunnel excavation. A parametric investigation is subsequently conducted to study the influence of tunnel depth, lateral coefficient, and free surface range on stress and displacement distribution in geomaterial.Comment: 45 pages, 14 figure

Advanced Theoretical and Computational Methods for Complex Materials and Structures

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

Tunnel Engineering

This volume presents a selection of chapters covering a wide range of tunneling engineering topics. The scope was to present reviews of established methods and new approaches in construction practice and in digital technology tools like building information modeling. The book is divided in four sections dealing with geological aspects of tunneling, analysis and design, new challenges in tunnel construction, and tunneling in the digital era. Topics from site investigation and rock mass failure mechanisms, analysis and design approaches, and innovations in tunnel construction through digital tools are covered in 10 chapters. The references provided will be useful for further reading

A study on deformation of tunnels excavated in fractured rocks

La déformation due au fluage d'un massif rocheux autour d'un tunnel a été rencontrée fréquemment. Ce phénomène est évident où il y a des tunnels creusés dans la roche tendre, des masses rocheuses faible et fortement cisaillées, ou des massifs rocheux soumis à des contraintes in-situ élevées. La déformation due au fluage se produit fréquemment au moment d’excavation des tunnels longs où il y a des failles et des zones fracturées et cisaillées. Ce phénomène peut causer différents dommages sur des systèmes de soutènement en raison de la déformation excessive et des effondrements. La déformation excessive impose une ré-excavation de la section du tunnel, qui monte le coût supplémentaire, la durée de la réalisation du projet et le risque de la sécurité sur le projet. En plus, comme la stabilité de terrain est dans un état critique durant la ré-excavation, une petite négligence peut conduire à une grande caverne. Bien que la déformation de fluage est commune dans un massif rocheux à une faible résistance dans un tunnel très profond, mais ce phénomène a été observé dans des tunnels peu profonds. Une bonne compréhension des déformations causées par une excavation souterraine requiert la connaissance de l'interaction roche-support et l'interprétation des données de terrain. Auparavant, l’objet principal de la surveillance effectuée durant la construction du tunnel était des mesures de la pression au terrain imposé sur le revêtement du tunnel. Mais aujourd’hui, les méthodes modernes de construction de tunnel se concentrent sur la surveillance des déplacements pendant et après la construction. Afin de déterminer des déformations dans les tunnels, Panet et Sulem ont supposé que "Le tunnel a une section transversale circulaire et le milieu est homogène et isotrope, aussi le tunnel est suffisamment profond pour considérer que la distribution des contraintes est homogène". Mais dans le cas quasi réel, la distribution de la contrainte autour du tunnel est hétérogène et anisotrope. Dans cette étude, pour la modification des équations Panet et Sulem, certaines équations sont proposées en cas de matériau hétérogène et anisotrope pour généraliser le problème. La galerie de force motrice Seymareh a été considérée comme l’étude de cas. Celle-ci est une partie du conduit d’eau dans le projet de centrale électrique du barrage Seymareh. Ce projet est situé à l'ouest de l'Iran. Les données de surveillance de la galerie de force motrice sont collectées au moment de l’excavation du tunnel, et sont comparées avec les résultats de la modélisation numérique et de la solution analytique. Cette comparaison montre que les résultats des données expérimentales obtenues par la surveillance sont très proches des résultats de la solution analytique, mais il y a une différence entre les deux et la modélisation numérique. Il était prévisible, car l’effet d’autres activités comme l’excavation des tunnels verticaux n’est pas prise en compte dans l’analyse numérique et aussi dans la solution analytique. Il est évident que les autres activités comme l’excavation des tunnels verticaux et l'excavation du tunnel principal vers deux directions opposées, peuvent affecter sur les résultats de la surveillance. D'autre part, les données initiales utilisées dans l'analyse numérique et la solution analytique ne sont pas tout à fait exactes, car elles sont obtenues en tant que représentatives du massif rocheux de la région, mais pas pour une section particulière. Toutefois, le but de cette étude est le développement d'une solution analytique de la déformation dans les tunnels sur les conditions générales et la poursuite de cette étude pourra être plus développée.The creep deformation of a rock mass around a tunnel has been encountered frequently. It is particularly common in tunnels excavated in soft rock, heavily sheared weak rock masses or rock masses subjected to high in-situ stresses. Creep deformation in fault and shear fractured zones are one of the frequently encountered difficulties in long tunnel construction, which tend to cause failure of supporting systems due to excessive deformation and cavern. Excessive deformation would necessitate re-mining of the tunnel cross section, thus imposing impacts such as extra cost, extended time schedule and safety risk on the project. Furthermore, as the ground stability is in critical condition during re-mining, the slightest negligence would lead to major cavern. Although creep deformation is common to extremely poor rock mass under high overburden in a tunnel alignment, but however this phenomenon is not limited to tunnels with high overburden. A good understanding of the deformations caused by an underground excavation requires simultaneously knowledge of the rock-support interaction and interpretation of field data. Formerly, the main purpose of the monitoring carried out during tunnel construction was to measure the ground pressures acting on the tunnel lining. Modern tunneling practice emphasizes the monitoring of the displacements occurring during and after the construction. Panet and Sulem for determining of deformations in tunnels have assumed that "The tunnel has a circular cross section and around the tunnel, the rock is homogeneous and isotropic and also the tunnel is deep enough to consider that the stress distribution is homogenous". But in almost real cases, the stresses distribution around the tunnel is not homogeneous and isotropic. In this study, for modification of the Panet and Sulem equations, some equations are proposed in case of nonhomogeneous and anisotropic for generalizing of the problem. Seymareh power tunnel which is considered as a case study is a part of the powerhouse waterways system of the Seymareh dam and hydroelectric power plant project. The project is located in west of Iran. The monitoring data of power tunnel which are collected during excavation of tunnel is compared with the results of numerical modelling and analytical solution results as well as. The results obtained from comparison show although the field data, which are collected through the monitoring, are very close to the analytical solution results (approximately), but there is a significant difference between both of them and numerical modelling results. It was predictable; because the influence of the other activities such as excavation of shaft and surge tank in the numerical analysis and also analytical solution are not considered. It is obvious that other activities such as excavation of shaft and surge tank and also excavation of mean tunnel from other direction which were under operation at the same time can effect on the results of monitoring. On the other hand, the initial data which are used in numerical analysis and analytical solution are not quite accurate; because they are extracted as a representative of the rock mass of region, not for a particular section. However the goal of this study is development of analytical solution of deformation in tunnels on general conditions and pursuit of the study could be leaded to more development in this field

Response of continuous pipelines to tunnel induced ground deformations

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2011.Cataloged from PDF version of thesis.Includes bibliographical references (p. 163-168).This thesis develops analytical solutions for estimating the bending moments and axial loads in a buried pipeline due to ground movements caused by tunnel construction in soft ground. The solutions combine closed-form, analytical solutions for tunnel-induced, free-field ground deformations in a plane orthogonal to the heading (Pinto and Whittle; 2001) with Winkler models for pipe-soil interactions. The free-field ground deformations are described in terms of two parameters describing the modes of cavity deformation and the elastic Poisson's ratio of the ground. The solutions have been evaluated by others through comparisons with well-instrumented case studies for a variety of different tunneling construction methods and ground conditions. Analytical approximations for the vertical and horizontal spring stiffness coefficients in the Winkler models are interpreted from numerical finite element analyses. The proposed analyses are compared with prior solutions proposed by Vorster (2005) and Klar et al. (2005) that rely on empirical procedures to estimate the ground deformations and focus only on bending response of the pipeline. The current research provides independent validation of the vertical spring coefficient proposed by Klar et al., and derives a novel interpretation of the horizontal spring coefficient. Results of the proposed analyses are presented graphically in design charts that show the deformations of the pipeline as functions of the pipe and tunnel geometry, tunnel cavity parameters, elastic properties of the ground and relative pipe-soil rigidity parameters. The solutions are used to re-analyze the deformations of a water main associated with a pipe-jacking procedure at an instrumented site in Chingford, London reported by Vorster (2005). The thesis also presents a hypothetical example that considers the impacts of the construction of a largediameter sewer tunnel in soft clay using EPB construction methods (using free-field performance data from the N-2 project in San Francisco) on existing utilities. In this case, potential damage to cast-iron water pipes is clearly linked to the pipe section properties and the EPB tunnel face pressure. Data from well-documented case studies must now be obtained to validate the proposed analyses.by Evangelia S. leronymaki.S.M

Mechanistic Framework for Risk Assessment of Cast Iron Water Main Fractures due to Moisture-Induced Soil Expansion

North American water distribution networks are at significant risk of failure due to aging cast iron pipes. For instance, of the 650,000 kilometers of cast-iron pipes in active service in the United States and Canada, more than 80% are beyond their intended service life. These aging and deteriorated pipes are failing at an alarming rate (22 breaks per 100 km per year), resulting in significant disruption to drinking and emergency water supply. The capital investment gap to replace this inventory is too large and will likely take several decades to bridge at the current replacement rate of the order of 0.8% per year. Meanwhile, infrastructure managers rely on managing this gap through simplistic replacement prioritization, e.g., the oldest pipes are the most at risk. Such age-based prioritization schemes disregard multiple risk drivers that contribute to pipe failure. Risk-based decision support frameworks that go beyond simple prioritization schemes by considering multiple risk drivers are necessary to identify and prioritize the most at-risk segments of the network, thereby leading to the better management of the aforementioned gap. Previous studies showed that localized corrosion flaws, also known as pitting corrosion, on the external surface are primarily responsible for damage in pipes, and the strength of these deteriorated pipes to withstand loadings constitutes their stress capacity. On the other hand, the stresses caused by different loads on the pipe comprise stress demand. Field failure data indicate that the plausible failure mechanism is flexure which causes “full-circle breaks.” In the Central and Northern California region, where expansive soils are prevalent, a majority of these beaks (~ 60%) occurred during the months of high rainfall. This suggests that the plausible loading mechanism is moisture-induced differential soil expansion/contraction. Despite that, studies focused on flexural failures driven by differential soil expansion and the overall reliability of pipes situated in environments where potential for moisture-induced differential soil expansion/contraction exists have not been studied well. In this thesis, a probabilistic framework is developed for the assessment of pipe-soil systems vulnerable to fracture caused by a combination of pitting corrosion and moisture-induced soil expansion. The main objectives of this thesis are twofold. First, a physics-based approach is employed to develop an analytical soil-pipe interaction model that can predict full-circle breaks given a range of parameters, such as pipe configuration, soil conditions, and triggering factors (soil expansion). The model is based on classical solutions for beams on elastic foundations that are enriched to reflect material nonlinearities in the soil medium. The model development and comparision are supported by a suite of continuum finite-element simulations that simulate detailed interactions between the pipe and soil. The proposed analytical model demonstrated that it is able to reproduce flexural stresses in a range of pipe configurations with good accuracy and in a fraction of the computational time compared to detailed finite-element models. Next, a risk-based assessment methodology is developed which builds upon this pipe-soil interaction model along with corrosion equations estimating pitting damage in the pipe wall. The sources of uncertainty (uncertainties in various input parameters and the model itself) in all the components are rigorously analyzed and characterized. Subsequently, stochastic simulations employing Monte Carlo procedure is implemented to synthesize various uncertainties into a probabilistic estimate of the failure of a pipe segment, defined by its configurational parameters and age. The prospective use of this is outlined in the context of decision-support frameworks to prioritize replacement. In summary, this thesis presents a physics-based approach to help identify the most at-risk cast iron main pipes given a combination of configurational, locational, and seasonal factors. The outcome of the research is (1) a computationally inexpensive pipe-soil interaction model for pipes experiencing moisture-induced differential soil expansion loading and (2) a vulnerability assessment framework for a pipe segment given its various characteristics and environmental/loading factors. This approach may be conveniently used by utility operators within a decision support framework for asset management and the prioritization of replacement

Protecting sensitive constructions from tunnelling: the case of World Heritage buildings in Barcelona

Permission is granted by ICE Publishing to print one copy for personal use. Any other use of these PDF files is subject to reprint fees.Construction of the tunnel for the high-speed Madrid–Barcelona–France railway link across central Barcelona became a major technical and social challenge due to the impact of the tunnel on nearby historic buildings (two of them, the Sagrada Familia basilica and Casa Milà, being United Nations Educational, Scientific and Cultural Organization (Unesco) World Heritage structures). Protection of sensitive buildings from tunnelling-induced movements relied on the construction of a stiff pile wall, separating the tunnel from historic sites. This paper first presents a simplified procedure to analyse the wall–tunnel interaction in a straightforward manner. The main features of the tunnel, excavated by means of an earth pressure balance machine in tertiary clays and sands below the water table, are then described. Details of the design of the wall that was finally built are presented. Issues that were particularly important include the groundwater flow constraints and the use of small-strain soil stiffness properties to obtain realistic settlements. General criteria to design the protection wall are also presented. The good performance of the wall resulted in negligible tunnelling impact on the sensitive structures. The measured and predicted displacements are compared, suggesting that this type of solution is adequate to protect historic structures from tunnelling.Peer ReviewedPostprint (published version

Sensitive analysis for optimizing the implementation of a quantitative method for dimensioning the preliminary support of tunnels

Tese de mestrado integrado. Engenharia Civil. Faculdade de Engenharia. Universidade do Porto. 201