Coding the “New Implicit Method” in MatLab for preliminary tunnel design

Abstract The tunnel design is a subject that demands a three-dimensional analysis dealing with two different players: lining and rockmass. The traditional methods of getting the necessary parameters for design do not consider a correct interaction between the two players, but the New Implicit Method (NIM) takes this characteristic in its core and develops some formulations for elastic, plastic and viscous rockmasses. Understanding that the stiffness of the lining and the distance between the lining and the tunnel face change the convergence of the tunnel, a code in MatLab for NIM is validated through Finite Element (FEM) with its results being presented. The validation of this method was compared with FEM analysis and the results obtained an average accuracy of 12% what represents a good approximation regarding geotechnical issues.