Simulation of 3D fracture propagation under I-II-III mixed-mode loading  

作　　者：Louis Ngai Yuen Wong Xin Cui 

机构地区：[1]Department of Earth Sciences,The University of Hong Kong,Pokfulam,Hong Kong,China [2]Now at Department of Earth,Atmospheric and Planetary Sciences,Massachusetts Institute of Technology,Cambridge,USA

出　　处：《Rock Mechanics Bulletin》2023年第4期70-83,共14页岩石力学通报（英文）

基　　金：support from National Natural Science Foundation of China under grant No.41877217;General Research Fund of the Research Grants Council (Hong Kong)under grant No.17200721;Natural Science Foundation of Guangdong Province under grant No.2019A1515010999.

摘　　要：Fracture propagation under mixed-mode loading conditions prevails in many natural geological processes and deep engineering projects,while the corresponding numerical simulation is very challenging in rock mechanics,especially in 3D cases.In most previous studies,the complexity of 3D fracture geometry was over-simplified,and model III loading was often not considered.In this study,we propose to use an efficient stress-based Sch€ollmann criterion combined with Displacement Discontinuity Method(DDM)to model 3D fracture propagation under arbitrary I+II+III mixed-mode loading conditions.A novel curve-smoothing algorithm is developed to smoothen the fracture front during propagation,which significantly enhances the model's ability in dealing with complex 3D fracture geometry.In particular,we adopt two different solution schemes,namely staggered and monolithic,to simulate mode I fracture propagation in the case of hydraulic fracturing.The accuracy,efficiency and convergency of the two solution schemes are compared in detail.Our research findings suggest that the degree of coupling between fracture aperture and fluid pressure in hydraulic fracturing lies somewhere between one-way and two-way,which favors the staggered solution scheme.To further test our new model,we provide three additional numerical examples associated with 3D fracture propagation under various mixed-mode loading conditions.Our model shows excellent performance in efficiently locating the new fracture front and reliably capturing the complex 3D fracture geometry.This study provides a generic algorithm to model high-fidelity 3D fracture propagation without simplifying fracture geometry or loading conditions,making it widely applicable to fracture-propagation-related problems.

关 键 词：3D fracture propagation Mixed-mode loading Sch€ollmann criterion Curve smoothing Hydro-mechanical(HM)coupling 

分 类 号：TU45[建筑科学—岩土工程]