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Over the last decades, constructions of large underground rock caverns are experiencing a rapid development across the globe. However design and construction of these structures is a complex and challenging task, specifically with limitations of limited investigations data and presence of many uncertainties.
Rock mass parameters along with joint configuration such as persistence, spacing and strength of the joints are the main factors which significantly modify stresses and displacements in the vicinity of the openings. This paper discusses continuum and discontinuum modelling of underground rock caverns based on case study of crude oil storage project located on southern coast of India.
Critical points of observation for these two types of analysis are reviewed in reference to results of the case study. Data obtained from geotechnical monitoring of underground rock cavern is also compared and discussed with the results obtained from both continuum and discontinuum analysis for better understanding of the same. The results obtained from this study indicate that inclusion of discontinuities in rock mass for numerical modelling captures essential instability conditions around the cavern while continuum representation gives a more idealised illustration of the instability.
Observed displacement values in most of the cases lie in between the calculated displacement values of continuum and discontinuum analysis.
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Gerrard CM Elastic models of rock masses having one, two and three sets of joints. Sharma KG Numerical analysis of underground structures. Indian Geotech J 39 1 :1— Singh B Continuum characterization of jointed rock masses Part I—the constitutive equations. J Rock Mech Sci Geomech — In: 3RD international symposium on block and sublevel caving, pp — Sitharam TG Equivalent continuum analyses of jointed rock mass: a practical approach, Chapter No In: Ramamurthy T ed Book-engineering in rocks for slopes, foundations and tunnels.
Prentice Hall of India, New Delhi, pp — ISBN Google Scholar. T, Fumio I Comparison of computational models for jointed rock mass through analysis of large scale cavern excavation. J Soil Mech Found Division — Comprehensive rock engineering. In: Hudson JA ed Analysis and design methods, vol 2.
Pergamon Press, Oxford, pp — Int J Impact Eng — Geoeng 9 2 — Kulatilake PHSW, Ucpirti H, Wang S, Radberg G, Stephansson O Use of the distinct element method to perform stress analysis in rock with non-persistent joints and to study the effect of joint geometry parameters on the strength and deformability of rock masses.
Rock Mech Rock Eng — Tunn Undergr Space Technol — Int J Rock Mech Min. Comput Geotech. Barton N Some new Q-value correlations to assist in site characterization and tunnel design.
Phase 2. Rocscience, Toronto. Bull Eng Geol Environ 64 1 — Bieniawski ZT Engineering rock mass classifications: a complete manual for engineers and geologists in mining, civil, and petroleum engineering. Wiley, New York. Geomech Geoeng — Barton N, Choubey V The shear strength of joints in theory and in practice.
Rock Mech — Barton N The shear strength of rock and rock joints. Balkema, Rotterdam, pp — Download references. The authors would like to thank the management of Engineers Indian Limited for granting permission to publish this paper. Correspondence to A. Reprints and Permissions. Usmani, A. Continuum and Discontinuum Analysis of Rock Caverns. Indian Geotech J 48, — Download citation. Received : 10 January Accepted : 26 July Published : 01 August Issue Date : December Search SpringerLink Search.
Abstract Over the last decades, constructions of large underground rock caverns are experiencing a rapid development across the globe. Immediate online access to all issues from Subscription will auto renew annually. References 1. In: 3RD international symposium on block and sublevel caving, pp — 5.
Balkema, Rotterdam, pp —10 Download references. Acknowledgements The authors would like to thank the management of Engineers Indian Limited for granting permission to publish this paper. Nanda Authors A. Usmani View author publications. View author publications.
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Tunnelling processes lead to stress changes surrounding an underground opening resulting in the disturbance and potential damage of the surrounding ground. Especially, when it comes to hard rocks at great depths, the rockmass is more likely to respond in a brittle manner during the excavation. Continuum numerical modelling and discontinuum techniques have been employed in order to capture the complex nature of fracture initiation and propagation at low-confinement conditions surrounding an underground opening. In the present study, the hybrid finite-discrete element method FDEM is used and compared to techniques using the finite element method FEM , in order to investigate the efficiency of these methods in simulating brittle fracturing. Following the comparison of these models, additional analyses are performed by integrating discrete fracture network DFN geometries in order to examine the effect of the explicit simulation of joints in brittle rockmasses. The results show that in both cases, the FDEM method is more capable of capturing the highly damaged zone HDZ and the excavation damaged zone EDZ compared to results of continuum numerical techniques in such excavations. Significant changes in the stress regime and material properties of a rockmass are the result of the construction of underground openings [ 1 ].
An imperative task for successful underground mining is to ensure the stability of underground structures. This is more so for deep excavations which may be under significantly high stresses. In this manuscript, we present stability studies on two tunnels, a horseshoe-shaped and an inverted arch-shaped tunnel, in a deep coal mine in China, performed using the 3DEC distinct element code. The rock mass mechanical property values for the tunnel shapes have been estimated through a back-analysis procedure using available field deformation data. The back-analysis has been carried out through a pseudo-time dependent support installation routine which incorporates the effect of time through a stress-relaxation mechanism. Additionally, the importance of incorporating stress relaxation before support installation has been illustrated through the increased support factor of safety and reduced grout failures. The calibrated models have been analyzed for different supported and unsupported cases to estimate the significance and adequacy of the current supports being used in the mine and to suggest a possible optimization.
The numerical models discussed in this paper are developed in finite element method FEM , finite deference method FDM , boundary element method and discrete element method and these tools are used to illustrate the behavior of tunnel structure deformation under different loads and in complicated conditions. Predicting the effect of all natural factors on tunnels is the most difficult method. One of the most significant advantages of the numerical method is in predicting the critical area surrounding the tunnel and the tunnel structure before making the tunnel construction due to different loads. Numerical modeling is used as control method in reducing the risk of tunnel construction failures. Since some factors such as settlement and deformation are not completely predictable in rock and soil surrounding the tunnel, using numerical modeling is a very economical and capable method in predicting the behavior of tunnel structures in various complicated conditions of loading. Another benefit of using numerical simulation is in the colorful illustrations predicting the tunnel behavior before, during and after construction and operation. There are not many conducted studies using numerical models to tunnel structures that estimate the critical zones.
PDF | The paper discusses continuum and discontinuum modelling in tunnel engineering. A brief review of fundamentals is presented in connection with the.
Barla, G. The paper is intended to demonstrate the use of continuum versus discontinuum modelling in tunnelling. A case study of a TBM tunnel 4.
Key-words: Tunnel engineering, Continuum and discontinuum mo- Kljufne rijeti: Tunelsko inicnjerstvo, Modelirane kontinuteta i delmg, TBM tunnel diskontinuitcta, TBM tunel Thc paper discusses continuum and discontinuum modelling in U Elanku je raspravljeno modeliranjc kontinuiteta i diskontinuiteta tunnel engineering. A bricf rcview of fundamentals is presented in u tunelskom inienjerstvu. Saieto su opisane osnove zajedno s upora- connection with the use of closed - formsolutions and computer bascd bom matematizkih rjeienja i raEunalnih numeriEkih metoda. Ra- methods. A few remarks are derived on the choice of either spravljen je izbor modela kontinuurna i diskontinuuma stjenske mase continuum or discontinuum modelling of rock mass behaviour at the u odnosu na analizu konstrukcije podgradivanja. U obzir je uzeto design analysis stage.
This work presents a comparative analysis between two model hierarchies commonly applied in tunnel structural design: continuum ground models and bedded-beam models. Firstly, the main characteristics of each model and the interfaces between them are discussed. Based on those evaluations a simple procedure is proposed for determining the bedded-beam model imposed loads which lead to results compatible to those of a given continuum model. Said procedure is then explored to estimate simplified compatibilization loads for basic and illustrative cases, where a reasonable compatibilization was achieved for a relatively simple applied load. Civil engineering applies mathematical models to simulate and solve physical problems of complex nature.
and tunnels. Due to Professor Barla's outstanding contribution and achievements to Rock. Mechanics and Rock Engineering, and the education.
Ha, Johnson, and Giovanni Grasselli. A tunnel in the region of Toronto, Canada, situated within the Georgian Bay shale and limestone formation, was simulated using the hybrid finite-discrete element method FDEM. The model was calibrated based on input parameters that adequately reproduced standardized laboratory rock tests. Through the simulations, various short-term excavation mechanisms were explored including the influence of rock support, rock mass heterogeneity and stress field anisotropy. Qualitatively, the models served as a method of quantifying risk in the case that unexpected ground conditions are encountered during construction.
Over the last decades, constructions of large underground rock caverns are experiencing a rapid development across the globe. However design and construction of these structures is a complex and challenging task, specifically with limitations of limited investigations data and presence of many uncertainties. Rock mass parameters along with joint configuration such as persistence, spacing and strength of the joints are the main factors which significantly modify stresses and displacements in the vicinity of the openings. This paper discusses continuum and discontinuum modelling of underground rock caverns based on case study of crude oil storage project located on southern coast of India. Critical points of observation for these two types of analysis are reviewed in reference to results of the case study. Data obtained from geotechnical monitoring of underground rock cavern is also compared and discussed with the results obtained from both continuum and discontinuum analysis for better understanding of the same.
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