scholarly journals Analysis of Face Stability during Excavation of Double-O-Tube Shield Tunnel

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Yuyou Yang ◽  
Qinghong Zhou ◽  
Hongan Li ◽  
Xuegang Huang ◽  
Xiaoming Tu
Keyword(s):  
Stability Analysis ◽  
Failure Mechanism ◽  
Three Dimensional ◽  
Soil Mass ◽  
Shield Tunnel ◽  
Face Stability ◽  
Supporting Pressure ◽  
The Face ◽  
Collapse Failure ◽  
Kinematic Theorem

This paper focuses on the face stability analysis of Double-O-Tube shield tunnel. This kind of analysis is significant to ensure the safety of workers and reduce the influence on the surrounding environment. The key point of the stability analysis is to determine the supporting pressure applied to the face by the shield. A collapse failure will occur when the supporting pressure is not sufficient to prevent the movement of the soil mass towards the tunnel. A three-dimensional collapse failure mechanism was presented in this paper. Based on the mechanism of a single circular shield tunnel, the mechanism of Double-O-Tube shield tunnel was established by using the fact that both of the mechanisms are symmetrical. Then by means of the kinematic theorem of limit analysis, the numerical results were obtained, and a design chart was provided. The finite difference software FLAC3D was applied to investigate the face failure mechanism of DOT shield tunnel established in this paper; the critical supporting pressures of the collapse failure mechanism in different strata (sand and silt) were calculated. Through comparative analysis, the theoretical values were very close to the numerical values. This shows that the face failure mechanism of DOT shield tunnel is reasonable, and it can be applied to the sand and silt strata.

An improved 3D wedge-prism model for the face stability analysis of the shield tunnel in cohesionless soils

2014 ◽  
Vol 10 (5) ◽  
pp. 683-692 ◽  
Author(s):  
R. P. Chen ◽  
L. J. Tang ◽  
X. S. Yin ◽  
Y. M. Chen ◽  
X. C. Bian
Keyword(s):  
Stability Analysis ◽  
Shield Tunnel ◽  
Cohesionless Soils ◽  
Face Stability ◽  
The Face ◽  
Wedge Prism ◽  
Prism Model

scholarly journals Upper Bound Analysis for Collapse Failure of Shield Tunnel Face Excavated in Unsaturated Soils Considering Steady Vertical Flow

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Jia-hua Zhang ◽  
Wei-jun Wang ◽  
Biao Zhang ◽  
Dao-bing Zhang
Keyword(s):  
Steady Flow ◽  
Upper Bound ◽  
Unsaturated Soils ◽  
Soil Mass ◽  
Shield Tunnel ◽  
Upper Bound Theorem ◽  
Tunnel Face ◽  
Supporting Pressure ◽  
Collapse Failure ◽  
Shield Tunnel Face

Natural soils are mostly in an unsaturated state and the corresponding mechanical properties differ significantly from a saturated one. In traditional stability analysis for a shield tunnel face, the soil mass is typically assumed to be dry or saturated for convenience of analysis. In this work, based on the upper bound theorem of classical plasticity theory and the log-spiral failure mechanism, face stability of the shield tunnel excavated in unsaturated soils under vertical steady flow is studied. The profile of shear strength is determined by virtues of the unified effective stress approach and the analytical solution of matric suction under unsaturated steady flow. On this basis, the analytical expression for the supporting pressure is deduced and the sequential quadratic programming is employed to search for the optimal upper bound solution. Through parametric analysis it is found the fitting parameters of SWCC and the groundwater level affect the supporting pressure notably. Besides, the relevant influence of vertical discharge is also significant when clayey soils are concerned.

The effect of water seepage forces on the face stability of an experimental microtunnel

1993 ◽  
Vol 30 (2) ◽  
pp. 363-369 ◽  
Author(s):  
Frédéric Pellet ◽  
François Descoeudres ◽  
Peter Egger
Keyword(s):  
Three Dimensional ◽  
Field Measurements ◽  
Shallow Depth ◽  
Equilibrium Analysis ◽  
Soft Ground ◽  
Tunnel Face ◽  
Element Analysis ◽  
Face Stability ◽  
Supporting Pressure ◽  
The Face

The face heading stability of underground constructions remains quite difficult to assess, especially when groundwater is present. To investigate this, an experimental microtunnel was excavated at shallow depth in soft ground, below the water table. In agreement with field measurements of the piezometric level changes, a three-dimensional finite element analysis of groundwater flow shows that the head losses are concentrated in the close vicinity of the tunnel face. Both numerical equilibrium analysis and field measurements were used to show that the resulting seepage forces substantially increase the supporting pressure required to ensure face stability. Key words : microtunnel, shallow depth, soft ground, seepage forces, face stability, supporting pressure.

Three-dimensional face stability analysis of shallow tunnels using numerical limit analysis and material point method

2021 ◽  
Vol 112 ◽  
pp. 103904
Author(s):  
Fabricio Fernández ◽  
Jhonatan E.G. Rojas ◽  
Eurípedes A. Vargas ◽  
Raquel Q. Velloso ◽  
Daniel Dias
Keyword(s):  
Stability Analysis ◽  
Limit Analysis ◽  
Three Dimensional ◽  
Material Point Method ◽  
Material Point ◽  
Point Method ◽  
Face Stability ◽  
Shallow Tunnels ◽  
Dimensional Face

scholarly journals 3D FEM Model on the Parameters’ Influence of EPB-TBM on Settlements of Single and Twin Metro Tunnels During Construction

2021 ◽  
Author(s):  
Masoud Forsat ◽  
Mohammad Taghipoor ◽  
Masoud Palassi
Keyword(s):  
Three Dimensional ◽  
Injection Pressure ◽  
Effective Parameters ◽  
Grout Injection ◽  
3D Fem ◽  
Supporting Pressure ◽  
Epb Tbm ◽  
The Face ◽  
Clear Distance ◽  
Twin Tunnels

AbstractThe present research exposes the investigation on three-dimensional modeling of the single and twin metro tunnels for the case of the Tehran metro line. At first, simulation implemented on the comparison of the ground movements in the single and twin tunnels. Then the simulation has been performed on the influence of effective parameters of EPB-TBM on the surface settlements throughout excavation. The overcutting, shield conicity, grouting, and the final lining system modeled and the influence of face supporting pressure, grout injection pressure, as well as the clear distance of the tunnels, has been analyzed. The initial results showed a valid ground settlement behavior. The maximum settlements occurred at the end of the shield tail and it was higher in the single tunnel. The face supporting pressure had more effect on the surface settlement in comparison to the grout injection pressure. By increasing the face pressure in the single tunnel, the place of maximum settlement moved back while the grout pressure is insignificant for decreasing the settlements. Furthermore, the influence of the clear distance in the twin tunnels led to zero after the length of 30 m. Accordingly, for more distances, the tunnels must be examined independently and as two different single tunnels.

Three-Dimensional Face Stability Analysis of EPBS Tunnels

2011 ◽  
Vol 378-379 ◽  
pp. 449-452
Author(s):  
Xue Gang Huang ◽  
Yu You Yang ◽  
Gui He Wang
Keyword(s):  
Three Dimensional ◽  
Earth Pressure ◽  
Pressure Balance ◽  
Circular Tunnel ◽  
Face Stability ◽  
Analysis Theory ◽  
The Face ◽  
Earth Pressure Balance Shield ◽  
Earth Pressure Balance ◽  
Kinematical Approach

A three-dimensional (3D) failure mechanism, based on the framework of the kinematical approach of limit analysis theory, is applied to calculate the face supporting pressure of a circular tunnel driven by the Earth Pressure Balance Shield (EPBS). The geometry of the mechanisms considered is composed of a sequence of truncated rigid cones. The numerical results obtained are presented.

scholarly journals 3D MODELLING OF TUNNEL EXCAVATION USING PRESSURIZED TUNNEL BORING MACHINE IN OVERCONSOLIDATED SOILS

2013 ◽  
Vol 35 (2) ◽  
pp. 3-17 ◽  
Author(s):  
Rafik Demagh ◽  
Fabrice Emeriault
Keyword(s):  
Numerical Simulation ◽  
Urban Areas ◽  
Three Dimensional ◽  
Ground Surface ◽  
Tunnel Boring Machine ◽  
Confining Pressure ◽  
Soil Mass ◽  
Shield Tunnel ◽  
Tunnel Boring ◽  
Boring Machines

Abstract The construction of shallow tunnels in urban areas requires a prior assessment of their effects on the existing structures. In the case of shield tunnel boring machines (TBM), the various construction stages carried out constitute a highly three-dimensional problem of soil/structure interaction and are not easy to represent in a complete numerical simulation. Consequently, the tunnelling- induced soil movements are quite difficult to evaluate. A 3D simulation procedure, using a finite differences code, namely FLAC3D, taking into account, in an explicit manner, the main sources of movements in the soil mass is proposed in this paper. It is illustrated by the particular case of Toulouse Subway Line B for which experimental data are available and where the soil is saturated and highly overconsolidated. A comparison made between the numerical simulation results and the insitu measurements shows that the 3D procedure of simulation proposed is relevant, in particular regarding the adopted representation of the different operations performed by the tunnel boring machine (excavation, confining pressure, shield advancement, installation of the tunnel lining, grouting of the annular void, etc). Furthermore, a parametric study enabled a better understanding of the singular behaviour origin observed on the ground surface and within the solid soil mass, till now not mentioned in the literature.

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