Research on Failure Mechanism and Parameter Sensitivity of Zonal Disintegration in Deep Tunnel

Abstract

"With the increase of excavation depth, the zonal disintegration phenomenon appears in the deep rock mass, which is quite different from the failure mode of shallow tunnel. In order to analyse the failure mechanism of this phenomenon, an elastoplastic softening damage model was put forward based on the softening damage characteristics of deep rock mass. The constitutive equations, the equilibriumequations,andthefailurecriterionwerededuced.Thetheoreticalsolutionsofradialdisplacementandradialstressesand tangential stresses of deep surrounding rock mass were calculated. The distribution law of zonal disintegration in deep tunnel was obtained. The theoretical solutions presented an oscillating mode. The theoretical calculated widths of fracture zones were in good agreementwiththeinsitutestdata.Besides,thesensitivityofdifferentparameterstofracturemorphologywascalculatedandanalysed. The results show that the relative loading strength has a controlling role in the zonal disintegration morphology, followed by the cohesionforceanddeformationmodulus,andtheinternalfrictionangleistheleast.Thisstudyrevealsthemorphologicalcharacteristics and influencing factors of zonal disintegration, which provides a basis for the prediction and support control of fracture modes. "