Limits...
Analysis of face stability during excavation of Double-O-Tube shield tunnel.

Yang Y, Zhou Q, Li H, Huang X, Tu X - ScientificWorldJournal (2013)

Bottom Line: This kind of analysis is significant to ensure the safety of workers and reduce the influence on the surrounding environment.Then by means of the kinematic theorem of limit analysis, the numerical results were obtained, and a design chart was provided.This shows that the face failure mechanism of DOT shield tunnel is reasonable, and it can be applied to the sand and silt strata.

View Article: PubMed Central - PubMed

Affiliation: School of Engineering and Technology, China University of Geosciences (Beijing), Beijing 100083, China.

ABSTRACT
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.

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The values of Nc.
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Related In: Results  -  Collection


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fig4: The values of Nc.

Mentions: The values of Nγ and Nc are provided in Figures 3 and 4, respectively. Table 1 presents the collapse pressures for two drained clays: (i) c = 5 kPa and φ = 15° (soft clay); (ii) c = 12 kPa and φ = 30° (stiff clay). The presented critical collapse pressures are calculated for the diameter of the tunnel that is equal to 10 m, and γ = 18 kN/m3. It is necessary to note that when the overburden ratio is high enough (C/D > 0.5), the mechanism is always with nooutcrop. It is the reason why the coefficient Ns is equal to zero, and Nγ and Nc are constant with the increase of C/D.


Analysis of face stability during excavation of Double-O-Tube shield tunnel.

Yang Y, Zhou Q, Li H, Huang X, Tu X - ScientificWorldJournal (2013)

The values of Nc.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3794543&req=5

fig4: The values of Nc.
Mentions: The values of Nγ and Nc are provided in Figures 3 and 4, respectively. Table 1 presents the collapse pressures for two drained clays: (i) c = 5 kPa and φ = 15° (soft clay); (ii) c = 12 kPa and φ = 30° (stiff clay). The presented critical collapse pressures are calculated for the diameter of the tunnel that is equal to 10 m, and γ = 18 kN/m3. It is necessary to note that when the overburden ratio is high enough (C/D > 0.5), the mechanism is always with nooutcrop. It is the reason why the coefficient Ns is equal to zero, and Nγ and Nc are constant with the increase of C/D.

Bottom Line: This kind of analysis is significant to ensure the safety of workers and reduce the influence on the surrounding environment.Then by means of the kinematic theorem of limit analysis, the numerical results were obtained, and a design chart was provided.This shows that the face failure mechanism of DOT shield tunnel is reasonable, and it can be applied to the sand and silt strata.

View Article: PubMed Central - PubMed

Affiliation: School of Engineering and Technology, China University of Geosciences (Beijing), Beijing 100083, China.

ABSTRACT
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.

Show MeSH