Publications

@article{Oke2018,

title = {Improvement to the Convergence-Confinement Method: Inclusion of Support Installation Proximity and Stiffness},

author = {J Oke and N Vlachopoulos and MS Diederichs},

doi = {10.1007/s00603-018-1418-0},

year  = {2018},

date = {2018-02-01},

journal = {Rock Mechanics and Rock Engineering},

volume = {51},

pages = {1495-1519},

abstract = {The convergence-confinement method (CCM) is a method that has been introduced in tunnel construction that considers the ground response to the advancing tunnel face and the interaction with installed support. One limitation of the CCM is due to the numerically or empirically driven nature of the longitudinal displacement profile and the incomplete consideration of the longitudinal arching effect that occurs during tunnelling operations as part of the face effect. In this paper, the authors address the issue associated with when the CCM is used within squeezing ground conditions at depth. Based on numerical analysis, the authors have proposed a methodology and solution to improving the CCM in order to allow for more accurate results for squeezing ground conditions for three different excavation cases involving various excavation-support increments and distances from the face to the supported front. The tunnelling methods of consideration include: tunnel boring machine, mechanical (conventional), and drill and blast.},

keywords = {Analytical, Convergence-confinement, Numerical modelling, Support, tunnelling},

pubstate = {published},

tppubtype = {article}

}

@article{Vlachopoulos2009,

title = {Improved longitudinal displacement profiles for convergence confinement analysis of deep tunnels},

author = {N Vlachopoulos and MS Diederichs},

doi = {10.1007/s00603-009-0176-4},

year  = {2009},

date = {2009-04-01},

journal = {Rock Mechanics and Rock Engineering},

volume = {42},

number = {2},

pages = {131-146},

abstract = {Convergence-confinement analysis for tunneling is a standard approach for preliminary analysis of anticipated wall deformation and support design in squeezing ground. Whether this analysis is performed using analytical (closed form) solutions or with plane strain numerical models, a longitudinal displacement profile (LDP) is required to relate tunnel wall deformations at successive stages in the analysis to the actual physical location along the tunnel axis. This paper presents a new and robust formulation for the LDP calculation that takes into account the significant influence of ultimate (maximum) plastic radius. Even after all parameters are appropriately normalized, the LDP function varies with the size of the ultimate plastic zone. Larger yield zones take a relatively longer normalized distance to develop, requiring an appropriately calculated LDP. Failure to use the appropriate LDP can result in significant errors in the specification of appropriate installation distance (from the face) for tunnel support systems. Such errors are likely to result in failure of the temporary support. The equations presented here are readily incorporated into analytical solutions and a graphical template is provided for use with numerical modeling.},

keywords = {Convergence-confinement, displacement, ground reaction, squeezing, tunnelling},

pubstate = {published},

tppubtype = {article}

}