A finite strain solution for the elastoplastic ground response curve in tunnelling: rocks with non-linear failure envelopes

This paper generalizes the finite strain Coulomb solution of Vrakas and Anagnostou (Int J Numer Anal Meth Geomech 2014; 38(11): 1131-1148) for the classic tunnel mechanics problem of the ground response curve to elastoplastic grounds satisfying a non-linear Mohr's failure criterion. A linear (Coulomb-type) plastic potential function is used, leading to a non-associated flow law, and edge plastic flow is considered in the plastic zone. The solution for a general non-linear Mohr's failure criterion is semi-analytical in that it requires the evaluation of definite integrals. In the special case of the Hoek-Brown criterion, however, these integrals are calculated analytically, resulting in a rigorous closed-form series solution. The applicability of the derived solution is illustrated through the example of the Yacambu-Quibor tunnel, where very large deformations were observed when crossing of weak graphitic phyllites. Copyright (c) 2016 John Wiley & Sons, Ltd.