3D morphology and formation mechanism of fractures developed by true triaxial stress  

作　　者：Bing Chen Baotang Shen Shichuan Zhang Yangyang Li Haiyang Jiang 

机构地区：[1]State Key Laboratory of Mining Disaster Prevention and Control Co-founded,Shandong University of Science and Technology,Qingdao 266590,China [2]CSIRO Mineral Resources,Queensland 4069,Australia [3]No.1 Institute of Geology and Mineral Resource Exploration of Shandong Province,Jinan 250010,China [4]College of New Energy and Environment,Jilin University,Changchun 130012,China

出　　处：《International Journal of Mining Science and Technology》2022年第6期1273-1284,共12页矿业科学技术学报（英文版）

基　　金：support from the National Natural Science Foundation of China(Nos.51974173 and 52004147);the Natural Science Foundation of Shandong Province(Nos.ZR2020QD122 and ZR2020QE129).

摘　　要：As main part of underground rock mass,the three-dimensional(3D)morphology of natural fractures plays an important role in rock mass stability.Based on previous studies on 3D morphology,this study probes into the law and mechanism regarding the influence of the confining pressure constraints on 3D morphological features of natural fractures.First,fracture surfaces were obtained by true triaxial compression test and 3D laser scanning.Then 3D morphological parameters of fractures were calculated by using Grasselli’s model.The results show that the failure mode of granites developed by true triaxial stress can be categorized into tension failure and shear failure.Based on the spatial position of fractures,they can be divided into tension fracture surface,S-1 shear fracture surface,and S-2 shear fracture surface.Micro-failure of the tension fracture surface is dominated by mainly intergranular fracture;the maximum height of asperities on the fracture surface and the 3D roughness of fracture surfaces are influenced by σ_(3) only and they are greater than those of shear fracture surfaces,a lower overall uniformity than tension fracture surface.S-1 shear fracture surface and S-2 shear fracture surface are dominated by intragranular and intergranular coupling fracture.The maximum height of asperities on the fracture surface and 3D roughness of fracture surface are affected by σ_(1),σ_(2),and σ_(3).With the increase of σ_(2) or σ_(3),the cutting off of asperities on the fracture surface becomes more common,the maximum height of asperities and 3D roughness of fracture surface further decrease,and the overall uniformity gets further improved.The experimental results are favorable for selecting technical parameters of enhanced geothermal development and the safety of underground mine engineering.

关 键 词：True triaxial stress Failure mode Fracture angle 3D morphology MICRO-FRACTURE 

分 类 号：TE319[石油与天然气工程—油气田开发工程]