Stability analysis of shallow tunnels subjected to eccentric loads by a boundary element method

Panji, Mehdi; Koohsari, Hamid; Adampira, Mohammad; Alielahi, Hamid; Marnani, Jafar Asgari

doi:10.1016/j.jrmge.2016.01.006

Cited by 42 publications

(7 citation statements)

References 26 publications

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“…e similarity material involves two mixture ratio tests: the soft clay and lining. As shown in Figure 2, based on the analysis of the plastic state and permeability of the soil, the soft clay material is simulated by using a combination of kaolin, bentonite, loess, and river sand [37,38]. Mix ratios of GPHS1 (4 : 2: 3 : 1) and GPHS2 (3 : 2: 4 : 1) are used in the tests.…”

Section: Similarity Materialmentioning

confidence: 99%

Model Test and Back Analysis of Shield Tunnel Load Distribution in Soft Clay

Niu

Weng

Tian

et al. 2021

Advances in Materials Science and Engineering

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Combined with the soft clay layer of Foshan metro, a back-analysis method combining model test and numerical simulation is developed. First, the similitude criterion for the model used in this study was derived from similarity theory and elasticity mechanics equations. Artificial clay is prepared by mixing kaolin, bentonite, loess, and river sand in proportions of 4 : 2: 3 : 1. Gypsum, water, and borax are mixed in proportions of 1 : 0.7 : 0.015 to simulate the tunnel lining. The model tests were carried out based on four load modes: the combination of mode 1, vertical load distribution and horizontal load linear distribution, mode 2, vertical load distribution and horizontal load parabolic distribution, mode 3, vertical load parabolic distribution and horizontal load linear distribution, and mode 4, vertical and horizontal load parabolic distribution. Then, the calculation model corresponding to the four load modes is established using ABAQUS, and the measured data is back-analyzed as the known quantity. The specific load values obtained were 359 kPa, 380 kPa, 361 kPa, and 368 kPa by the load-internal force curve. The bending moment and axial force are calculated by substituting the back-analysis load values back into the model and comparing the results with the measured values; it was found that the internal forces under the back-calculation load still deviated by varying degrees. By using the comprehensive error function E to evaluate the advantages and disadvantages of the four distribution modes, the comprehensive errors are 4.3%, 1.7%, 6.5%, and 5.9%, respectively. That is, the error of load distribution of mode 2 (the combination of vertical load distribution and horizontal load parabolic distribution) is the lowest and is highly consistent with the measured value, which is the closest to the characteristics of the load pattern of the stratum.

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Section: Similarity Materialmentioning

confidence: 99%

Model Test and Back Analysis of Shield Tunnel Load Distribution in Soft Clay

Niu

Weng

Tian

et al. 2021

Advances in Materials Science and Engineering

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“…where δ a1 , δ a2 , and δ a3 are constants. e radial displacement u R d at the plastic-BIDZ interface is obtained by substituting r � R d into equation (23).…”

Section: Advances In Civil Engineeringmentioning

confidence: 99%

“…Furthermore, the relation between support pressure and tunnel convergence at the roof is unusual compared with that at the side wall because the gravity forces do not exist at the side wall. Several researchers have analyzed the impact of rock gravity on the ground reaction of circular tunnels excavated in M-C, H-B, or GHB rock mass [1,2,[20][21][22][23][24]. ey thought that the dead weight of the material in the broken zone can be represented by body forces acting radially towards the centre of the circular tunnel.…”

Section: Introductionmentioning

confidence: 99%

Unified Analytical Solutions of Circular Tunnel Excavated in an Elastic‐Brittle‐Plastic Rock Mass considering Blast‐Induced Damage and Dead Weight Loading

Cao

Chen

et al. 2021

Advances in Civil Engineering

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Stress and deformation around circular tunnel are crucial for optimizing the support system and evaluating the tunnel stability. The damage zone induced by blasting or mechanical excavation can dramatically influence the support design and methods because the self-weight of broken rock mass at the roof of the tunnel can exert a high pressure on the support system, leading to the support system instability due to the overload. This paper presents a new closed-form solution for analyzing the stress and deformation of deep circular tunnel excavated in elastic-brittle rock mass with the consideration of the rock gravity and damage zone by using the unified strength criterion. A new modified equilibrium equation in the fracture zone is used to determine the stress and the radius of fracture zone. The correctness of the solution is also verified by comparison with the numerical simulation results. The results illustrate that the rock gravity, damage zone radius, and intermediate principal stress have an extremely important influence on the ground response. The tunnel surface convergence and damage zone radius with the consideration of the gravity are obviously larger than those without consideration of the gravity. The rock gravity effect under the high intermediate principal stress gradually weakens, illustrating that the intermediate principal stress is beneficial to tunnel stability. Large deformation instability of the tunnel is dependent on the extension of damage zone. The larger the radius of damage zone, the larger both fracture range and tunnel surface deformation. The proposed solution in this study is novel and can be used to assess the ground convergence for different scenarios and to optimize the support system during the early design stage of the tunnel.

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“…This method has many advantages such as high accuracy due to the semi-analytical nature and use of integrals, increase the efficiency with dimension reduction of problems that resulting a considerable reduction in computer time and cost, high-precision modeling in infinite domain problems and thin shell-like structures/materials, solving large-scale problems with complicated geometries and etc [1][2][3][4]. During the last decade many engineering problems have been solved using BEM, such as three dimensional static fracture and fatigue crack growth [5], numerical simulation of three-dimensional double-diffusive natural convection in porous media [6], solving acoustic problems in open-boundary domains [7], solving heat conduction problems [8], stability analysis of shallow tunnels subjected to eccentric loads [9], modeling of fluid flow in periodic cell with porous cylinder [10], hydrofoil analysis [11], steady state convection diffusion radiation problems [12].…”

Section: Introductionmentioning

confidence: 99%

Solving the Nonlinear Two-Dimension Wave Equation Using Dual Reciprocity Boundary Element Method

Mahmoodi¹,

Ghassemi²,

Heydarian³

2017

IJPDEA

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The boundary element method (BEM) is a very effective numerical tool which has been widely applied in engineering problems. Wave equation is a very important equation in applied mathematics with many applications such as wave propagation analysis, acoustics, dynamics, health monitoring and etc. This paper presents to solve the nonlinear 2-D wave equation defined over a rectangular spatial domain with appropriate initial and boundary conditions. Numerical solutions of the governing equations are obtained by using the dual reciprocity boundary element method (DRBEM). Two-dimension wave equation is a time-domain problem, with three independent variables , , . At the first the Laplace transform is used to reduce by one the number of independent variables (in the present work ), then Salzer's method which is an effective numerical Laplace transform inversion algorithm is used to recover the solution of the original equation at time domain. The present method has been successfully applied to 2-D wave equation with satisfactory accuracy.

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Stability analysis of shallow tunnels subjected to eccentric loads by a boundary element method

Cited by 42 publications

References 26 publications

Model Test and Back Analysis of Shield Tunnel Load Distribution in Soft Clay

Model Test and Back Analysis of Shield Tunnel Load Distribution in Soft Clay

Unified Analytical Solutions of Circular Tunnel Excavated in an Elastic‐Brittle‐Plastic Rock Mass considering Blast‐Induced Damage and Dead Weight Loading

Solving the Nonlinear Two-Dimension Wave Equation Using Dual Reciprocity Boundary Element Method

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