MODELIRANJE KONTINUITETA I DISKONTINUITETA U TUNELSKOM INŽENJERSTVU

The paper discusses continuum and discontinuum modelling in tunnel engineering. A brief review of fundamentals is presented in connection with the use of closeg - form solutions and computer based numerical methods. a few remarks are derivedon the choice of either continuum or discontinuum modelling of rock mass behaviour at the design analysis stage. Consideration is given to the validation of discontinuum modelling in connection with rock mass classification methods and expected tunnel response to excavation. A case study of a TBM tunnel (4.75 m) in quartzitic micaschists is discussed in detail by paying attention to a comparison of modelling methods - including continuum and discontinuum modelling - applied at a fault zone.U članku je raspravljeno modeliranje kontinuiteta i diskontinuiteta u tuelskom inženjerstvu. Sažeto su opisane osnove zajedno s uporabom matematičkih rješenja i računalnih numeričkih metoda. Raspravljen je izbor modela kontinuuma i diskontinuuma stjenske mase u odnosu na analizu konstrukcije podgrađivanja. U obzir je uzeto potvrđivanje modela diskontinuiteta povezanog s metodama klasifikacije stjenskih masa i očekivane reakcije tunela pri iskopu. U detaljima je raspravljen prmjer studije TBM tunela (promjera 4,75 m) u kvarcitičnim mikašistima s posebnom pozornosti na uspoređivanje metoda modeliranja - uključujući modeliranje kontinuuma i diskontinuuma - uporabljenih u rasjednoj zoni

Numerical modeling of deep-seated landslides interacting with man-made structures

This paper describes the interaction between deep-seated landslides and man-made structures such as dams, penstocks, viaducts, and tunnels. Selected case studies are reported first with the intent to gain insights into the complexities associated with the interaction of these structures with deep-seated landslides (generally referred to as deep-seated gravity slope deformations, DSGSDs). The main features, which characterize these landslides, are mentioned together with the interaction problems encountered in each case. Given the main objective of this paper, the numerical modeling methods adopted are outlined as means for increase in the understanding of the interaction problems being investigated. With the above in mind, the attention moves to an important and unique case history dealing with the interaction of a large-size twin-tunnel excavated with an earth pressure balance (EPB) tunnel boring machine (TBM) and a deep-seated landslide, which was reactivated due to the stress changes induced by tunnel excavation in landslide shear zone. The geological and geotechnical conditions are described together with the available monitoring data on the landslide movements, based on the advanced and conventional monitoring tools used. Numerical modeling is illustrated as an aid to back-analyze the monitored surface and subsurface deformations and to assist in finding the appropriate engineering solution for putting the tunnel into service and as a follow-up means for future understanding and control of the interaction problems. The simulation is based on a novel time-dependent model representing the landslide behavior. Keywords: Deep-seated landslides, Man-made structures, Landslide-structure interaction, Monitoring of landslide movement, Numerical modelin

Full-face excavation of large tunnels in difficult conditions

Abstract Following a few preliminary remarks on the tunneling methods at the beginning of the 20th century, the successful applications of the full-face method also in difficult conditions are underlined. The attention is posed on the use of a systematic reinforcement of the face and of the ground, by means of fiber-glass elements. A selection of tunnels where this method was used successfully is reported with the purpose of illustrating the wide spectrum of ground conditions where it has been applied. Then, following a description of the main concepts behind the method, the attention moves from the so-called "heavy method", where deformations are restrained, to the "light method", where deformations are allowed with the intention to decrease the stresses acting on the primary and final linings. The progress in the application of the "light method" is underlined, up to the development of a novel technique, which relies on the use of a yielding support composed of top head steel sets with sliding joints and special deformable elements inserted in the primary lining. The well-known case study of the Saint Martin La Porte access adit, along the Lyon-Turin Base Tunnel, is described. In this tunnel, a yield-control support system combined with full-face excavation has been adopted successfully in order to cope with the large deformations experienced during face advance through the Carboniferous formation. The monitoring results obtained during excavation are illustrated, together with the modeling studies performed when paying attention to the rock mass time-dependent behavior

Performance monitoring and analysis of a yield-control support system in squeezing rock

ISBN 978-0-415-58654-

Wave propagation in discontinuous media

Wave propagation in discontinuous media, which is of interest for design analysis of underground structures and geotechnical works in general, is studied in this paper with the scattering matrix method. This method determines the response of a system, i.e. the discontinuous medium, excited by an elastic wave. Both P, SV or SH waves can be applied to the model with any oblique angle of incidence. The scattering matrix is composed of reflection and transmission coefficients of a single joint or a set of parallel joints. The analytical solution is obtained in the frequency domain and allows one to consider multiple wave reflections between joints. Reflected and transmitted waves are calculated for one and more joints in dry or fluid filled conditions. The solutions obtained are compared with analytical and numerical solutions available in the literature or obtained independently by using the Distinct Element Metho

MODELIRANJE KONTINUITETA I DISKONTINUITETA U TUNELSKOM INŽENJERSTVU

The paper discusses continuum and discontinuum modelling in tunnel engineering. A brief review of fundamentals is presented in connection with the use of closeg - form solutions and computer based numerical methods. a few remarks are derivedon the choice of either continuum or discontinuum modelling of rock mass behaviour at the design analysis stage. Consideration is given to the validation of discontinuum modelling in connection with rock mass classification methods and expected tunnel response to excavation. A case study of a TBM tunnel (4.75 m) in quartzitic micaschists is discussed in detail by paying attention to a comparison of modelling methods - including continuum and discontinuum modelling - applied at a fault zone.U članku je raspravljeno modeliranje kontinuiteta i diskontinuiteta u tuelskom inženjerstvu. Sažeto su opisane osnove zajedno s uporabom matematičkih rješenja i računalnih numeričkih metoda. Raspravljen je izbor modela kontinuuma i diskontinuuma stjenske mase u odnosu na analizu konstrukcije podgrađivanja. U obzir je uzeto potvrđivanje modela diskontinuiteta povezanog s metodama klasifikacije stjenskih masa i očekivane reakcije tunela pri iskopu. U detaljima je raspravljen prmjer studije TBM tunela (promjera 4,75 m) u kvarcitičnim mikašistima s posebnom pozornosti na uspoređivanje metoda modeliranja - uključujući modeliranje kontinuuma i diskontinuuma - uporabljenih u rasjednoj zoni

Manuscripts Using Numerical Discrete Element Methods

The creation of numerical discrete element methods was a breakthrough in modeling discontinuous media and thus in modeling of rock masses. Recent developments in this domain, as also shown in a Special Issue of our Journal (Volume 45, Issue 5, September 2012), make it possible to simulate rock on any scale from intact rock composed of several particles to rock masse

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