Stability of symmetric wedge formed in the roof of a circular tunnel: nonhydrostatic natural stress field

Sofianos, A.I.; Nomikos, Pavlos; Tsoutrelis, C.E.

doi:10.1016/s0148-9062(99)00033-9

Cited by 21 publications

(14 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In order to determine the initial stress conditions acting on the joints, the method proposed by Sofianos et al (1999) has been adopted here by assuming that the joints are infinitely stiff and that the excavation is carried out in homogenous, linearly elastic medium ignoring gravity. Furthermore, the case of a non-hydrostatic biaxial stress field acting around a circular tunnel is considered to represent the natural stress field at a depth below the surface, where the horizontal stress is different to the vertical stress (see Fig.…”

Section: Evaluation Of the Initial Stress Acting On The Joint Surfacementioning

confidence: 99%

“…The roof of a tunnel in a jointed rock mass will often contain blocks whose stability depends on their geometry, the mechanical properties of the joints, the method and shape of the excavation, fluid pressures, the deformability of the block and of the surrounding rock mass, as well as the in situ stresses (Crawford and Bray 1983;Brady and Brown 2004;Elsworth 1986;Goodman and Boyle 1987;Sofianos et al 1999;Asadollahi and Tonon 2010;Indraratna et al 2010). In the past, methods of analysing the stability of a block in the roof of a tunnel were typically based on the limit equilibrium of forces (Goodman and Shi 1985;Brady and Brown 2004;Warburton 1981).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Stability of a Rock Block in a Tunnel Roof Under Constant Normal Stiffness Conditions

Thirukumaran

Indraratna

Brown³

et al. 2015

Rock Mech Rock Eng

View full text Add to dashboard Cite

Section: Evaluation Of the Initial Stress Acting On The Joint Surfacementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Stability of a Rock Block in a Tunnel Roof Under Constant Normal Stiffness Conditions

Thirukumaran

Indraratna

Brown³

et al. 2015

Rock Mech Rock Eng

View full text Add to dashboard Cite

“…Excavation development procedures may affect these internal forces. For example, uncontrolled blasting practice near the excavation periphery will inject high-pressure gases directly into the joints, promote vertical displacement greater than Figure 9.16 Symmetrical wedge in the crown of a circular excavation (after Sofianos et al, 1999). that associated with elastic joint deformability, and thereby reduce the final horizontal force responsible for block retention in the crown of the opening.…”

Section: Symmetric Triangular Roof Prismmentioning

confidence: 99%

“…For the particular case of a symmetrical wedge in the crown of a circular opening, Sofianos et al (1999) considered an opening of radius R in a deviatoric stress field defined by p and K 0 p, with the principal stress axes oriented in the vertical and horizontal directions. The problem geometry for a wedge of height, h, is shown in Figure 9.16.…”

Section: Symmetric Triangular Roof Prismmentioning

confidence: 99%

Rock Mechanics for underground mining

Brady

Brown

2004

View full text Add to dashboard Cite

No part of this work may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, microfilming, recording or otherwise, without written permission from the Publisher, with the exception of any material supplied specifically for the purpose of being entered and executed on a computer system, for exclusive use by the purchaser of the work.

show abstract

“…Using a model that is closer to reality and considers the existence of joints ought to provide more realistic results and an optimal design. Both the safety margin and safety factor for block stability are calculated directly from the ultimate pullout force, which depends on the clamping forces, so the estimation of clamping forces has a direct influence on safety assessment. Therefore, the main objective of this paper is to deepen the understanding of the development of clamping forces and the block failure process in a blocky ground.…”

Section: Introductionmentioning

confidence: 99%

A new analytical solution based on joint relaxation for analyzing symmetrical block stability

Bagheri

Stille

2011

Num Anal Meth Geomechanics

View full text Add to dashboard Cite

SUMMARYThe magnitude of clamping forces has a significant influence on the estimated ultimate pullout force of a block. The Crawford-Bray equation, which is fundamental in considering clamping forces, is only a function of horizontal stress and block height. Further research to incorporate the influence of induced stress in block stability analysis was considered, but all the previous analytical solutions for analyzing block stability assume a continuum medium to estimate clamping forces and do not allow joint deformations to occur before block movement due to gravity. Assuming a continuous medium to estimate clamping forces leads to an overestimation of block stability and therefore unsafe design. In this paper, an attempt has been made to deepen the understanding of the block failure mechanism and correct the estimated magnitude of clamping forces in a discontinuous medium. A conceptual model is proposed based on the loading-unloading of the block from an in-situ state to failure. Based on this model, an analytical solution has been developed that calculates clamping forces in a discontinuous medium. The validity and model uncertainty of the solution were checked for different conditions. The new analytical solution is both precise and accurate and can be used as a design tool to estimate block stability. Copyright © 2011 John Wiley & Sons, Ltd. Block failure is not just one of the most common failure modes in tunnels but is also very complex. Various design tools such as kinematic analysis, analytical solutions and numerical discrete methods are available to analyze block stability. Analytical solutions are particularly important since they provide a conceptual description of the complex failure mechanism as well as a basis for understanding the interaction between factors governing block stability. Analytical solutions can also be used to generate the performance function for probabilistic analysis.Calculation of block stability based on ignoring clamping forces produces an uneconomical design [1]. On the other hand, an overestimation of clamping forces leads to an unsafe design. The precise estimation of clamping forces is thus a critical issue. The analytical solutions for estimating clamping forces available today [2][3][4][5][6][7][8][9][10][11] are based on continuum mechanics and may overestimate the clamping forces. A comparison of results using the numerical discrete method and CrawfordBray's analytical solution [12] showed a significant difference in calculated block stability. One explanation could be that clamping forces in a discontinuous medium are generally lower due to stress relaxation of joints than those calculated using continuous mechanics [12,13].Crawford and Bray [2] assumed constant clamping forces when in reality clamping forces change from the initial state, due to excavation and block movements. Using a model that is closer to reality

show abstract

Stability of symmetric wedge formed in the roof of a circular tunnel: nonhydrostatic natural stress field

Cited by 21 publications

References 2 publications

Stability of a Rock Block in a Tunnel Roof Under Constant Normal Stiffness Conditions

Stability of a Rock Block in a Tunnel Roof Under Constant Normal Stiffness Conditions

Rock Mechanics for underground mining

A new analytical solution based on joint relaxation for analyzing symmetrical block stability

Contact Info

Product

Resources

About