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Geomechanics and Engineering
  Volume 15, Number 1, May20 2018, pages 621-630
DOI: https://doi.org/10.12989/gae.2018.15.1.621
 


Catastrophe analysis of active-passive mechanisms for shallow tunnels with settlement
X.L. Yang and H.Y. Wang

 
Abstract
    In the note a comprehensive and optimal passive-active mode for describing the limit failure of circular shallow tunnel with settlement is put forward to predict the catastrophic stability during the geotechnical construction. Since the surrounding soil mass around tunnel roof is not homogeneous, with tools of variation calculus, several different curve functions which depict several failure shapes in different soil layers are obtained using virtual work formulae. By making reference to the simple-form of Power-law failure criteria based on numerous experiments, a numerical procedure with consideration of combination of upper bound theorem and stochastic medium theory is applied to the optimal analysis of shallow-buried tunnel failure. With help of functional catastrophe theory, this work presented a more accurate and optimal failure profile compared with previous work. Lastly the note discusses different effects of parameters in new yield rule and soil mechanical coefficients on failure mechanisms. The scope of failure block becomes smaller with increase of the parameter A and the range of failure soil mass tends to decrease with decrease of unit weight of the soil and tunnel radius, which verifies the geomechanics and practical case in engineering.
 
Key Words
    optimization; shallow tunnels; functional catastrophe theory; settlement effect
 
Address
X.L. Yang and H.Y. Wang: School of Civil Engineering, Central South University, Hunan 410075, China
 

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