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.

scholarly journals Influence of Tunnel Boring Machine (TBM) Advance on Adjacent Tunnel during Ultra-Rapid Underground Pass (URUP) Tunneling: A Case Study and Numerical Investigation

2020 ◽  
Vol 10 (11) ◽  
pp. 3746
Author(s):  
Chao Liu ◽  
Zhuohua Peng ◽  
Liufeng Pan ◽  
Hai Liu ◽  
Yubing Yang ◽  
...  
Keyword(s):  
Earth Pressure ◽  
Bending Moment ◽  
Tunnel Boring Machine ◽  
Soil Arching ◽  
Tunnel Face ◽  
Element Analysis ◽  
Tunnel Boring ◽  
Supporting Pressure ◽  
Grouting Pressure ◽  
The Face

This study investigates the influence of subsequent tunnel boring machine (TBM)-driven processes on the responses of the first tunnel in twin-tunnel construction using the ultra-rapid underground pass (URUP) method. A comprehensive finite element analysis (FEA) is performed to simulate the URUP TBM tunneling, considering the non-uniform convergence caused by the TBM geometry, the tunnel face supporting pressure, and the tail-grouting pressure. The FEA model is validated by the monitoring results of the bending element of the first tunnel lining. The FEA results reveal that the grouting pressure of the second tunnel has significant influence on lining deformation of the first tunnel, while the face supporting pressure shows little effect. The relationship between the grouting pressure and the maximum bending moment of adjacent first tunnel can be fitted by linear function. A grouting pressure equals to the lateral earth pressure is able the reduce the variation of the bending element of the first tunnel during the TBM-driven process of the second tunnel. The bending element of the first tunnel shows a typical lognormal relationship with the face supporting pressure during the TBM advance of the second tunnel. A critical cover-to-depth ratio, under which the horizontal and vertical soil arching effect vanishes, can be deduced to be within the range of 0.55–0.60.

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.

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 undrained tunnel face stability in clay with a linearly increasing shear strength with depth

2017 ◽  
Vol 88 ◽  
pp. 146-151 ◽  
Author(s):  
Boonchai Ukritchon ◽  
Kongkit Yingchaloenkitkhajorn ◽  
Suraparb Keawsawasvong
Keyword(s):  
Shear Strength ◽  
Three Dimensional ◽  
Tunnel Face ◽  
Face Stability ◽  
Tunnel Face Stability

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.

The Track Structural Design and Finite Element Analysis of the Track Type Thinning Shredder

2012 ◽  
Vol 490-495 ◽  
pp. 2888-2892
Author(s):  
Yan Wu ◽  
Yan Ma
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Structural Design ◽  
Three Dimensional ◽  
Soft Ground ◽  
Mechanical Motion ◽  
Element Analysis ◽  
Development Cycle ◽  
Speed Up ◽  
Forestry Industry

Using the powerful parametric features of Pro/E modeling for the assembly of the track board, and building up Three-dimensional solid modeling. Finite element analysis with the simulation of mechanical motion to simulate the track through the soft ground of the forest were carried out. It can significantly reduce the design costs and speed up the development cycle to adapt of the requirements of the modern forestry industry.

scholarly journals The Vanderbilt Concrete Canoe Design Project: The Little Engine that Canoed

2006 ◽  
Vol 2 ◽  
Author(s):  
Stephen Brian Schmitt
Keyword(s):  
Three Dimensional ◽  
Element Analysis ◽  
Team Members ◽  
Railroad Industry ◽  
School History ◽  
Dimensional Finite Element ◽  
The Face ◽  
Three Dimensional Finite Element ◽  
Project Objectives ◽  
First Time

The Vanderbilt Concrete Canoe (VCC) Team has a competitive history at the Southeastern Regional ASCE Conference, placing in the top five schools throughout the past three years. The most recent concrete canoe project was named The Little Engine That Canoed in 2006 to honor Commodore Cornelius Vanderbilt’s origins in the railroad industry and as a reminder of the power of persistence. Developing The Little Engine was a small portion of the overall project objectives. The design team first compiled a significant body of literature that systematically outlined the steps for a successful concrete canoe project. The Little Engine boasts a fresh hull, three-dimensional finite element analysis, and an optimized concrete composite. The canoe construction efforts yielded a female mold, canoe carrier, and stands. Team members found the process of modeling the V-shaped bow and stern sections and a rounded stern stem to be the most challenging obstacles. Three-dimensional analysis was performed for the first time in school history and provided insight into graduate level coursework. Similarly, designing a concrete composite to withstand the rigors of competition required the use of a polymer to replace water in the concrete mix. To reach new heights, the team utilized a functional breakdown structure. Teamwork and communication, in the face of limited manpower, resulted in performing over 800 man-hours of concrete canoe related activities during a two-year period.

Three-Dimensional Analysis of Excavating Face Stability Supported by Pipe Roof

2013 ◽  
Vol 275-277 ◽  
pp. 1257-1263 ◽  
Author(s):  
Xiang Yuan ◽  
Shun Hua Zhou ◽  
Quan Mei Gong
Keyword(s):  
Analytical Solution ◽  
Dimensional Analysis ◽  
Load Transfer ◽  
Three Dimensional ◽  
Subgrade Reaction ◽  
Large Section ◽  
Tunnel Face ◽  
Face Stability ◽  
Tunnel Face Stability ◽  
The Stability

This paper analyzes the load transfer characteristics of pipe roof over the excavating face, and the analytical solution of tunnel face stability is established by the method of three-dimensional analysis. Through the calculation of the load transfer of the pipe roof, it indicates that the released load of excavation is passed to the supporting structure and soil which is not excavated by the effect of the pipe roof, and the magnitude of load and coverage of impact are in connection with excavating footage as well as subgrade reaction. The three-dimensional analytical solution of tunnel face stability is used to analyze a project case of Airport Road underpass in Hangzhou. The results show that the tunnel face stability is not guaranteed when excavated on a large section while the stability is enhanced when excavated on separated pilot headings.

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