Fast methods to solve the unloading problem of a cylindrical cavity or tunnel excavated in elasto-perfectly plastic, elasto-brittle or strain-softening materials under a hydrostatic stress feld can be derived based on...Fast methods to solve the unloading problem of a cylindrical cavity or tunnel excavated in elasto-perfectly plastic, elasto-brittle or strain-softening materials under a hydrostatic stress feld can be derived based on the self-similarity of the solution. As a consequence, they only apply when the rock mass is homogeneous and so exclude many cases of practical interest. We describe a robust and fast numerical technique that solves the tunnel unloading problem and estimates the ground reaction curve for a cylindrical cavity excavated in a rock mass with properties depending on the radial coordinate, where the solution is no longer self-similar. The solution is based on a continuation-like approach(associated with the unloading and with the incremental formulation of the elasto-plastic behavior), fnite element spatial discretization and a combination of explicit sub-stepping schemes and implicit techniques to integrate the constitutive law, so as to tackle the diffculties associated with both strong strain-softening and elasto-brittle behaviors. The developed algorithm is used for two practical ground reaction curve computation applications. The frst application refers to a tunnel surrounded by an aureole of material damaged by blasting and the second to a tunnel surrounded by a ring-like zone of reinforced(rock-bolted) material.展开更多
With respect to constitutive models for continuum modeling applications, the post-yield domain remainsthe area of greatest uncertainty. Recent studies based on laboratory testing have led to thedevelopment of a number...With respect to constitutive models for continuum modeling applications, the post-yield domain remainsthe area of greatest uncertainty. Recent studies based on laboratory testing have led to thedevelopment of a number of models for brittle rock dilation, which account for both the plastic shearstrain and confining stress dependencies of this phenomenon. Although these models are useful inproviding an improved understanding of how dilatancy evolves during a compression test, there hasbeen relatively little work performed examining their validity for modeling brittle rock yield in situ. Inthis study, different constitutive models for rock dilation are reviewed and then tested, in the context of anumber of case studies, using a continuum finite-difference approach （FLAC）. The uncertainty associatedwith the modeling of brittle fracture localization is addressed, and the overall ability of mobilizeddilation models to replicate in situ deformation measurements and yield patterns is evaluated. 2014 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting byElsevier B.V. All rights reserved.展开更多
基金the Spanish Ministry of Science and Technology for fnancial support awarded under Contract Reference Numbers BIA2009-09673 and MTM2010-21235-C02-02
文摘Fast methods to solve the unloading problem of a cylindrical cavity or tunnel excavated in elasto-perfectly plastic, elasto-brittle or strain-softening materials under a hydrostatic stress feld can be derived based on the self-similarity of the solution. As a consequence, they only apply when the rock mass is homogeneous and so exclude many cases of practical interest. We describe a robust and fast numerical technique that solves the tunnel unloading problem and estimates the ground reaction curve for a cylindrical cavity excavated in a rock mass with properties depending on the radial coordinate, where the solution is no longer self-similar. The solution is based on a continuation-like approach(associated with the unloading and with the incremental formulation of the elasto-plastic behavior), fnite element spatial discretization and a combination of explicit sub-stepping schemes and implicit techniques to integrate the constitutive law, so as to tackle the diffculties associated with both strong strain-softening and elasto-brittle behaviors. The developed algorithm is used for two practical ground reaction curve computation applications. The frst application refers to a tunnel surrounded by an aureole of material damaged by blasting and the second to a tunnel surrounded by a ring-like zone of reinforced(rock-bolted) material.
基金funding support from the Natural Sciences and Engineering Research Council of Canada (NSERC)the Center for Excellence in Mining Innovation (CEMI)the Nuclear Waste Management Organization of Canada (NWMO)
文摘With respect to constitutive models for continuum modeling applications, the post-yield domain remainsthe area of greatest uncertainty. Recent studies based on laboratory testing have led to thedevelopment of a number of models for brittle rock dilation, which account for both the plastic shearstrain and confining stress dependencies of this phenomenon. Although these models are useful inproviding an improved understanding of how dilatancy evolves during a compression test, there hasbeen relatively little work performed examining their validity for modeling brittle rock yield in situ. Inthis study, different constitutive models for rock dilation are reviewed and then tested, in the context of anumber of case studies, using a continuum finite-difference approach （FLAC）. The uncertainty associatedwith the modeling of brittle fracture localization is addressed, and the overall ability of mobilizeddilation models to replicate in situ deformation measurements and yield patterns is evaluated. 2014 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting byElsevier B.V. All rights reserved.
