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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Cross-section of the collapse failure mechanism associating with a single circular tunnel in the (y, z) plane.
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Related In: Results  -  Collection


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fig1: Cross-section of the collapse failure mechanism associating with a single circular tunnel in the (y, z) plane.

Mentions: As mentioned previously, the generation of the mechanism associating with the DOT tunnel is based on that of a single circular tunnel. To better introduce the geometrical construction of the 3D failure mechanism of the DOT tunnel, it is necessary to introduce that of a single circular tunnel at first. Figure 1 shows the cross-section of the mechanism in the vertical plane passing through the tunnel axis. The diameter of the tunnel is D, and C represents the cover depth. As shown in Figure 1, the mechanism is composed of a truncated conical block and a rotational curvilinear cone (the shape of the cone is like a “horn”), and the “horn” is located on the conical block; the contacting cross-section Σ1 is circular. The opening angle of the conical block is equal to 2φ. The rotational curvilinear cone can be described by two log spirals r1 and r2, which emerg from A and E, respectively, and share a common center O. The two log spirals intersect at point F. Their respective equations in a polar (r, β) coordinate system are as follows:(8)r1=rA·exp⁡((α−β)·tanφ),r2=rE·exp⁡((β−α)·tanφ),where rA and rE represent the distance between O and A and E, respectively. The central point O is located D/n above the tunnel as shown in Figure 1. Consider that(9)rA=1ncos⁡α·D,rE=[1ncos⁡α+cos⁡(α+φ)cos⁡φ]·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)

Cross-section of the collapse failure mechanism associating with a single circular tunnel in the (y, z) plane.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

fig1: Cross-section of the collapse failure mechanism associating with a single circular tunnel in the (y, z) plane.
Mentions: As mentioned previously, the generation of the mechanism associating with the DOT tunnel is based on that of a single circular tunnel. To better introduce the geometrical construction of the 3D failure mechanism of the DOT tunnel, it is necessary to introduce that of a single circular tunnel at first. Figure 1 shows the cross-section of the mechanism in the vertical plane passing through the tunnel axis. The diameter of the tunnel is D, and C represents the cover depth. As shown in Figure 1, the mechanism is composed of a truncated conical block and a rotational curvilinear cone (the shape of the cone is like a “horn”), and the “horn” is located on the conical block; the contacting cross-section Σ1 is circular. The opening angle of the conical block is equal to 2φ. The rotational curvilinear cone can be described by two log spirals r1 and r2, which emerg from A and E, respectively, and share a common center O. The two log spirals intersect at point F. Their respective equations in a polar (r, β) coordinate system are as follows:(8)r1=rA·exp⁡((α−β)·tanφ),r2=rE·exp⁡((β−α)·tanφ),where rA and rE represent the distance between O and A and E, respectively. The central point O is located D/n above the tunnel as shown in Figure 1. Consider that(9)rA=1ncos⁡α·D,rE=[1ncos⁡α+cos⁡(α+φ)cos⁡φ]·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