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Geomechanics and Engineering Volume 10, Number 1, January 2016 , pages 21-35 DOI: https://doi.org/10.12989/gae.2016.10.1.021 |
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Collapse mechanism of tunnel roof considering joined influences of nonlinearity and non-associated flow rule |
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X.L. Yang, J.S. Xu, Y.X. Li and R.M. Yan
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| Abstract | ||
| Employing non-associated flow rule and Power-Law failure criterion, the failure mechanisms of tunnel roof in homogeneous and layered soils are studied in present analysis. From the viewpoint of energy, limit analysis upper bound theorem and variation principle are introduced to study the influence of dilatancy on the collapse mechanism of rectangular tunnel considering effects of supporting force and seepage force. Through calculation, the collapsing curve expressions of rectangular tunnel which are excavated in homogeneous soil and layered soils respectively are derived. The accuracy of this work is verified by comparing with the existing research results. The collapsing surface shapes with different dilatancy coefficients are draw out and the influence of dilatancy coefficient on possible collapsing range is analyzed. The results show that, in homogeneous soil, the potential collapsing range decreases with the decrease of the dilatancy coefficient. In layered soils, the total height and the width on the layered position of possible collapsing block increase and the width of the falling block on tunnel roof decrease when only the upper soil's dilatancy coefficient decrease. When only the lower soil's dilatancy coefficient decrease or both layers' dilatancy coefficients decrease, the range of the potential collapsing block reduces. | ||
| Key Words | ||
| collapse; non-associated flow rule; Power-Law criterion; tunnel roof; upper bound | ||
| Address | ||
| School of Civil Engineering, Central South University, Hunan 410075, China. | ||