Application of Convergence–Confinement Method in Analysis of Shallow Non-circular Tunnels

Mousivand, Mohsen; Maleki, Mohammad; Nekooei, Masoud; Mansoori, Mohammad Reza

doi:10.1007/s10706-017-0173-4

Cited by 22 publications

(7 citation statements)

References 26 publications

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“…To distinguish whether the stress at the points C and E are in the elastic or the plastic regions, this study presents two analysis situations that include that stress state of As shown in the upper part of Figure 1, the third curve of this method is called the longitudinal displacement profile (LDP) [11] or the confinement loss curve (CLC) [2][3][4]. Recent studies have shown some divergent views on the assumptions and definitions of confinement loss in the CCM analysis [29][30][31][32][33]. This principle suggests that the confinement loss increases while the radial stress decreases during the advancing excavation of the tunnel face and uses the concept of increment to simulate this effect, and its value is between 0 and 1 [3,34,35].…”

Section: Equations Derivation Of the Direct Calculation Methods (Dcm)mentioning

confidence: 99%

Verification and Comparison of Direct Calculation Method for the Analysis of Support–Ground Interaction of a Circular Tunnel Excavation

et al. 2022

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A direct algorithmic process can deal with the solution of the support–ground interaction in a circular tunnel excavation through the convergence-confinement method (CCM) with the concept of increment. This process is the so-called direct calculation method (DCM) that can find solutions, the mobilized support pressure and the convergence, in the analysis of CCM. To achieve the solution, using two linear equations in the elastic region and Newton’s recursive method to find the roots in the plastic region are proposed and realized by a calculated spreadsheet. The validity of the algorithmic process for the analytical solutions was investigated and verified by the finite element computation, and compared with the published results, Rocksupport (2004), Oreste (2009), and Gschwandtner-Galler (2012). The results obtained between DCM and related studies show no significant differences.

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Section: Equations Derivation Of the Direct Calculation Methods (Dcm)mentioning

confidence: 99%

Verification and Comparison of Direct Calculation Method for the Analysis of Support–Ground Interaction of a Circular Tunnel Excavation

et al. 2022

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“…As been summarized in Karakus, several practical methods were presented for accounting for the 3D tunnelling effect in 2D analysis. The convergence‐confinement method is taken here, which considers that the stress of surrounding medium is gradually released (or the vertical displacements of the surrounding medium are gradually increased) with increasing of distance from the excavation face. Based on the convergence‐confinement method, the authors give assumptions that pseudosupport is provided by the soil before the tunnel face, which reduces smoothly with the distance from the tunnel face x .…”

Section: Numerical Implementationmentioning

confidence: 99%

Stability analysis of shotcrete supported crown of NATM tunnels with discontinuity layout optimization

Zhang

Zhuang

Lackner

2018

Num Anal Meth Geomechanics

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Summary For tunnel constructed by New Austrian Tunnelling Method, the crown is the upper part of tunnel section, constructed during excavation process and supported by shotcrete. The stability of the crown has great influence on the safety of tunnel itself and the buildings above, which correlates, among others, with geometrical setup of tunnel and material properties of shotcrete and soil/rock. In this paper, aiming at analyzing the stability of shotcrete supported crown, a recently presented numerical method discontinuity layout optimization is adopted, which introduces a great amount of potential discontinuities cross over one another and provides a wide search space for efficient upper limit analysis. In the analysis, a well‐established hydration model of cementitious material is implemented for accounting the hydration of shotcrete. Then assumptions based on convergence‐confinement method are used for accounting the 3‐dimensional effect in 2‐dimensional analysis, finally providing time‐space–dependent assessments of stability of shotcrete supported crown.

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“…To study the stress release of the surrounding rock and the stress characteristics of the supporting structure [22] during tunnel excavation, numerical calculations [23][24][25][26] and field tests [27,28] are commonly used, and the numerical calculation model must be revised by the data of field tests before it has reference value.…”

Section: Introductionmentioning

confidence: 99%

Design of Tunnel Initial Support in Silty Clay Stratum Based on the Convergence-Confinement Method

Liu

Zhao

et al. 2023

Sustainability

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The stress release ratio of the surrounding rock in tunnel excavation is one of the most important indicators that affect the stress distribution and displacement of the surrounding rock. To determine the variation law of the stress release ratio of the surrounding rock during excavation in silty clay stratum, the stress release law is determined based on the convergence–confinement method (CCM) and field test data. The stress release law of the surrounding rock under support is determined based on the displacement back analysis method. The permitted displacement safety factor of silty clay under different subgrade conditions and the optimal supporting time of the initial supporting structure are determined by comparing the stress release ratio with surrounding rock displacement. The results indicated that the stress release ratio of surrounding rock in the silty clay stratum is approximately 78–90% when the coordinate displacement of the supporting structure and surrounding rock is stable under the current excavation and support conditions. For the surrounding rock of subgrade V in the silty clay stratum, the safety factor of the permitted displacement in the tunnel vault is approximately 2.91, and the initial support should be carried out within 1 m behind the face advancing. For the surrounding rock of subgrade VI1, the safety factor of the permitted displacement is 1.40, and the initial support must be carried out 1 m ahead of the tunnel face. For the surrounding rock of grade VI2, the initial support must be carried out 4 m ahead of the tunnel face.

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Application of Convergence–Confinement Method in Analysis of Shallow Non-circular Tunnels

Cited by 22 publications

References 26 publications

Verification and Comparison of Direct Calculation Method for the Analysis of Support–Ground Interaction of a Circular Tunnel Excavation

Verification and Comparison of Direct Calculation Method for the Analysis of Support–Ground Interaction of a Circular Tunnel Excavation

Stability analysis of shotcrete supported crown of NATM tunnels with discontinuity layout optimization

Design of Tunnel Initial Support in Silty Clay Stratum Based on the Convergence-Confinement Method

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