A numerical approach for design of bolt-supported tunnels regarded as homogenized structures

Bernaud, Denise; Maghous, Samir; Buhan, Patrick de; Couto, Eduardo Costa

doi:10.1016/j.tust.2009.02.002

Cited by 41 publications

(23 citation statements)

References 11 publications

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“…Comprehensive series of studies have been conducted to analytically model the bolting effect on rock mass. Most of them have considered the grouted bolt contribution to rock mass in the form of a radial load inducing the radial pressure within the influence domain of itself , that is,

{σ_{r}}^{comp} = σ_{r} - \frac{T}{C} .

…”

Section: Analytical Simulation Of the Bolt Influence On The Radial Stmentioning

confidence: 99%

“…The theoretical study of fully grouted rockbolts as a stabilizing system of tunnels has been of considerable attention during the last decades . A number of solutions, which take the interaction between the bolt and the rock mass into account, have been based on the assumption that the contribution of bolt to the rock mass is in the form of a radial pressure within the influence domain of each bolt .…”

Section: Introductionmentioning

confidence: 99%

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Analytical‐numerical solution for stress distribution around tunnel reinforced by radial fully grouted rockbolts

Ranjbarnia

Oreste

Fahimifar

et al. 2016

Num Anal Meth Geomechanics

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Summary This paper presents an analytical‐numerical approach to obtain the distribution of stresses and deformations around a reinforced tunnel. The increase in the radial stress of the reinforced tunnel, based on the performance of a bolt, is modeled by a function, which its maximum value is in the vicinity of the bolt periphery and it exponentially decreases in the far distance from the bolt. On the basis of this approach, the shear stiffness between the bolt and the rock mass and the shear stress distribution around the bolt within the rock mass are also analytically obtained. The results are compared with those obtained by the assumption of ‘uniform increase of radial stress’ method, which is made by the previous studies. The analyses show when the bolts' spacing is large, the safety factor must be increased if the ‘uniform increase of radial stress’ method is used for the design. Finally, a procedure is introduced to calculate the non‐equal deformation of the rock mass between the bolts at any radius that can be useful to compute the bending moment in shotcrete layer in New Austrian Tunnelling Method (NATM) approach. Copyright © 2016 John Wiley & Sons, Ltd.

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{σ_{r}}^{comp} = σ_{r} - \frac{T}{C} .

…”

Section: Analytical Simulation Of the Bolt Influence On The Radial Stmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Analytical‐numerical solution for stress distribution around tunnel reinforced by radial fully grouted rockbolts

Ranjbarnia

Oreste

Fahimifar

et al. 2016

Num Anal Meth Geomechanics

View full text Add to dashboard Cite

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“…The tunnel is discretized with thick shell elements, the local coordinates of which are determined by the nodes of elements. The tunnel is treated as a homogeneous model, which is considered as an alternative [31] to get the whole responses of the tunnel and determine the dangerous cross-sections while maintaining a moderate system equation for computation. The mesh dimension is determined through a series of mesh sensitivity tests which also assure the accuracy of the results.…”

Section: Finite Element Model Overviewmentioning

confidence: 99%

“…As shown in Figure 9, the external manifestation of PML is a wave absorbing layer placed at the boundary of a truncated model which absorbs and attenuates waves propagating outward of the truncated model [37]. Assuming that the coordinate system tψ i u is adopted to describe the 3D space and the coordinates system ψ i 1 ( transformed from tψ i u is supposed as the PML's wave absorbing space, the stretching function can be expressed as (no summation) [31,33]:…”

Section: Boundary Conditions and Input Seismic Wavementioning

confidence: 99%

Parallel Dynamic Analysis of a Large-Scale Water Conveyance Tunnel under Seismic Excitation Using ALE Finite-Element Method

et al. 2016

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Abstract:Parallel analyses about the dynamic responses of a large-scale water conveyance tunnel under seismic excitation are presented in this paper. A full three-dimensional numerical model considering the water-tunnel-soil coupling is established and adopted to investigate the tunnel's dynamic responses. The movement and sloshing of the internal water are simulated using the multi-material Arbitrary Lagrangian Eulerian (ALE) method. Nonlinear fluid-structure interaction (FSI) between tunnel and inner water is treated by using the penalty method. Nonlinear soil-structure interaction (SSI) between soil and tunnel is dealt with by using the surface to surface contact algorithm. To overcome computing power limitations and to deal with such a large-scale calculation, a parallel algorithm based on the modified recursive coordinate bisection (MRCB) considering the balance of SSI and FSI loads is proposed and used. The whole simulation is accomplished on Dawning 5000 A using the proposed MRCB based parallel algorithm optimized to run on supercomputers. The simulation model and the proposed approaches are validated by comparison with the added mass method. Dynamic responses of the tunnel are analyzed and the parallelism is discussed. Besides, factors affecting the dynamic responses are investigated. Better speedup and parallel efficiency show the scalability of the parallel method and the analysis results can be used to aid in the design of water conveyance tunnels.

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“…These coefficients were used as the multipliers to obtain the confinement stress of composite material. Grasso et al (1989) and Bernaud et al (2009) works are also the other attempts to model the composite material properties.…”

Section: Introductionmentioning

confidence: 99%

New Analytical Approaches for Evaluating the Performance of Systematic Pre-Tensioned Fully Grouted Rockbolts in Tunnel Stabilization

Ranjbarnia

Fahimifar

Oreste

2016

Archives of Mining Sciences

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In this paper, two new analytical approaches are presented on the basis of convergence-confinement method to compute both the ultimate convergence of circular tunnel and its plastic zone having been reinforced by systematically pre-tensioned fully grouted rockbolts. The models have two basic assumptions: (1) the grouted rockbolts increase the radial internal pressure within a broken rock mass by both the pre-tensioned force and the probable following induced force due to rock mass movement (2) tunnel convergence (specially short-term) occurs only due to reducing and diminishing of the radial constrained stress on tunnel surface provided by the working face. Hence, the values of both the pre-tensioned pressure and the mentioned radial constrained stress are specially taken into consideration in this paper. That is, according to their magnitudes, two different conditions occur: the magnitude of pre-tensioned pressure is greater than that of the constrained stress at bolt installation time and vice versa. The solutions are extended to each of conditions, and illustrative examples are solved. The proposed approaches predicting almost identical results show that pre-tensioning of grouted rockbolts will increase the efficiency and effectiveness of rockbolts.Keywords: analytical approach; tunneling design; convergence-confinement method; pre-tensioned fully grouted rockbolt W pracy tej przedstawiono dwie analityczne metody oparte na metodzie badania konwergencji i naprężeń wymuszonych wykorzystane do obliczania zarówno granicznej konwergencji tunelu o przekroju koła oraz zachowania strefy plastycznej, po wzmocnieniu tunelu za pomocą wstępnie naprężanych i zacementowanych kotew. Model opiera się dwóch założeniach: (1) zacementowane kotwy prowadzą do wzrostu ciśnienia wewnętrznego w kierunku promieniowym w kruszonym materiale skalnym, spowodowanego siłą wstępnego naprężenia oraz siłą spowodowaną przez ruchy górotworu; (2) -konwergencja

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A numerical approach for design of bolt-supported tunnels regarded as homogenized structures

Cited by 41 publications

References 11 publications

Analytical‐numerical solution for stress distribution around tunnel reinforced by radial fully grouted rockbolts

Analytical‐numerical solution for stress distribution around tunnel reinforced by radial fully grouted rockbolts

Parallel Dynamic Analysis of a Large-Scale Water Conveyance Tunnel under Seismic Excitation Using ALE Finite-Element Method

New Analytical Approaches for Evaluating the Performance of Systematic Pre-Tensioned Fully Grouted Rockbolts in Tunnel Stabilization

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