Installation Time of an Initial Support for Tunnel Excavation upon the Safety Factors of Surrounding Rock

In engineering practice, the initial support system is commonly installed in the vicinity of the tunnel face after excavation, whereas the self-capacity of rock mass will fail to be utilized and the cost of the initial support system will be expensive. In this study, a methodology is proposed to det...

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Bibliographic Details
Published in:Applied sciences 2020-08, Vol.10 (16), p.5653
Main Authors: Zhang, Yan-Jun, Su, Kai, Zhu, Hong-Ze, Qian, Zhong-Dong, Wu, He-Gao
Format: Article
Language:English
Subjects:
Engineering
Excavation
initial ground support
Installation
Methods
Numerical analysis
Rock masses
Rocks
Safety
safety factor
Safety factors
Stability analysis
Stress state
Support systems
Theory
Tunnel construction
tunnel excavation
tunnel stability
Yield stress
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Summary:In engineering practice, the initial support system is commonly installed in the vicinity of the tunnel face after excavation, whereas the self-capacity of rock mass will fail to be utilized and the cost of the initial support system will be expensive. In this study, a methodology is proposed to determine the appropriate timing of initial support installation to find out the balance of tunnel safety and construction cost. Firstly, the global safety factor is introduced as the critical indicator to evaluate tunnel stability. Then, the comprehensive graphic relationship between the global safety factor and the distance to the tunnel face is established. Once the global safety factor decreases to an admissible value, the stability of the surrounding rock is in a critical state and the corresponding distance is the recommended location for installing the initial support. In these procedures, the installation time of the initial support at the typical tunnel section can be quickly designed and fed back by a direct indicator during construction. Meanwhile, several cases with different conditions have been carried out to discuss the regularity of the method.
ISSN:2076-3417
2076-3417
DOI:10.3390/app10165653