scholarly journals KEY FACTORS IN THE FACE STABILITY ANALYSIS OF SHALLOW TUNNELS

2013 ◽  
Vol 10 (9) ◽  
pp. 1025-1038 ◽  
Author(s):  
Dias
2021 ◽  
Vol 112 ◽  
pp. 103904
Author(s):  
Fabricio Fernández ◽  
Jhonatan E.G. Rojas ◽  
Eurípedes A. Vargas ◽  
Raquel Q. Velloso ◽  
Daniel Dias

2018 ◽  
Vol 28 (4) ◽  
pp. 566-589 ◽  
Author(s):  
Zhiqiang Zhang ◽  
Huayun Li ◽  
Hongyu Yang ◽  
Bo Wang

For shallow tunnels under soft grounds, it is very difficult to gain a complete understanding on all the load-bearing arch effects during excavation, since such tunnels can easily deform or even collapse. Among these effects, the tunnel face stability plays the most important role and has not been understood and handled very well; therefore, the design and construction of such tunnels under soft grounds remain as a challenge. In this work, the different failure models of face instability of the shallow tunnels were established based on the upper-bound theorem of limit analysis for the formation of clayey and sandy soils, respectively, and the analytical equations for determining the limit support force for the face stability were also derived. Furthermore, the influences of various factors on the stability were analyzed and compared. For the sandy soil formation, an equivalent pressure coefficient was proposed for the tunnel faces of bolt reinforcement. Finally, taking the face stability of the shallow tunnels in sandy soils as an example, a complete numerical simulation was conducted to verify the accuracy and effectiveness of the analytical results based on the theoretical models as well as their application conditions.


2014 ◽  
Vol 10 (5) ◽  
pp. 683-692 ◽  
Author(s):  
R. P. Chen ◽  
L. J. Tang ◽  
X. S. Yin ◽  
Y. M. Chen ◽  
X. C. Bian

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Yuyou Yang ◽  
Qinghong Zhou ◽  
Hongan Li ◽  
Xuegang Huang ◽  
Xiaoming Tu

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.


2017 ◽  
Vol 68 (10) ◽  
pp. 2378-2381
Author(s):  
Cristian Budacu ◽  
Mihai Constantin ◽  
Iulia Chiscop ◽  
Carmen Gabriela Stelea ◽  
Raluca Dragomir

Post-operative alveolitis is a topical issue in dental practice, which is also reflected by the etiopathogenic aspects. The conservative principle requires the maintenance of dento-periodontal units in the arch for as long as possible, but there are situations where dental extraction is required. The healing process of the post-surgical wound is complex and involves processes of gingival mucosal regeneration and bone reshaping, involving several local factors: wound size, presence of infection, alveolar vascularization, intraalveolar foreign bodies, and general factors, especially general condition, age and body reactivity. The quality, structure, maintenance, and retraction of the clot are key factors in the formation of connective tissue during the healing of the post-extraction would. At the Oral and Maxillofacial Surgery Clinic of Gala�i, during a 2-year period between January 2015 and December 30, 2016, 2780 patients that required surgery - dental extraction were consulted and diagnosed. We found that among those 2780 patients with dental extractions 105 (3.77%) had post-treatment alveolitis. No post-surgical alveolitis from the case study was complicated by osteomyelitis of the jaws or by suppurations of the superficial or deep compartments of the face. The prophylactic measures in each dental extraction, together with the correct and timely curative treatment, combined with the dentist�s competence and responsibility, can shorten the time of suffering, actively combating the risk factor and accelerating the social reintegration of the patient with post-treatment alveolitis.


Author(s):  
Ping Lu ◽  
Dajun Yuan ◽  
Jian Chen ◽  
Dalong Jin ◽  
Jun Wu ◽  
...  

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