Abstract
With the construction of underground rock engineering, the surrounding rock in deep tunnels appears zonal disintegration of fracture and intact zones alternate distribution, which is a special engineering geological phenomenon. This study establishes a partitioned fracture model under the coupling of high in-situ stress and osmotic pressure, and identify the key influencing factors of the fracture model. Furthermore, a stress intensity factor (SIF) of initial cracks on surrounding rock elastoplastic boundary is derived using the transformation of complex functions. Considering the high seepage pressure of the surrounding rocks, a zonal fracture initiation criterion is established combined with the analysis of redistributed stress fields. Finally, the obtained criterion is embedded into an extended finite element method (XFEM) platform for numerical simulation. Taking the maximum circumferential tensile stress as a cracking criterion, the propagation trajectory of rock cracks is traced by contour methods. Calculation results have realized the modelling of a whole process of crack initiation, propagation, and formation. And the established criterion has be verified.
Highlights
Deep rock mechanics has become a hot research area in the field of rock mechanics because it meets the needs of a series of new scientific phenomena such as the deformation and failure of surrounding rocks in deep rock engineering
Zonal disintegration refers to the phenomenon of alternating fractured and non-fractured areas in surrounding rocks during the excavation of tunnels in deep rock mass [1]
Shemyakin (1986) first verified the zonal disintegration found in Taimyrskii's deep mining site through model tests [5]
Summary
Deep rock mechanics has become a hot research area in the field of rock mechanics because it meets the needs of a series of new scientific phenomena such as the deformation and failure of surrounding rocks in deep rock engineering. In terms of the causes and formations of zone disintegration, Zhou and Qian [6] used fracture mechanics theory. Guzev [10] used a non-Euclidean geometric model to study the reasons for the periodic changes in the shape (distribution range) of fracture zones with the stress of surrounding rocks. Metolov [11] believes that parameter weakening caused by unloading of surrounding rocks is the reason for the non-monotonic change of stress in zonal fracture. A partitioned fracture evolution model under the coupling of high in-situ stress and osmotic pressure is established, and the key influencing factors of the fracture mode are identified.
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