Open Geosciences 2020; 12: 406–424 Research Article Yaoguang Huang*, Aining Zhao, Tianjun Zhang, and Weibin Guo Plastic failure zone characteristics and stability control technology of roadway in the fault area under non-uniformly high geostress: A case study from Yuandian Coal Mine in Northern Anhui Province, China https://doi.org/10.1515/geo-2020-0154 Keywords: elastic–plastic analysis, plastic failure, non- received February 18, 2020; accepted May 21, 2020 uniformly high geostress, fault area, roadway support Abstract: In order to explore the effective support method for deep broken roadway, based on the in situ stress test results, the analytical and numerical solutions of the stress and the range of plastic failure zone (PFZ) in 1 Introduction a circular roadway subjected to non-uniform loads were obtained using analytical and finite difference numerical Faced with the current predicament of the depletion of ( methods based on the elastoplastic theory, respectively. shallow mineral resources, many coal mines mining ) ( Their comparison results show that the analytical and depth is up to 1,500 m and mines of metal ores mining ) numerical methods are correct and reasonable. Furthe- depth is up to 4,500 m have to enter the stage of deep [ ] rmore, the high geostress causes the stress and range of mineral extraction 1,2 , which has brought a lot of new fl PFZ in roadway roof and floor to increase sharply while problems and challenges. Under the strong in uence of “ - those in roadway ribs decrease. Moreover, the greater the three high and one disturbance high geostress, high difference of horizontal geostress in different horizontal ground temperature, high karst water pressure, and ” directions is, the larger the range of PFZ in roadway roof mining disturbance , the roadway surrounding rocks and floor is. The shape of PFZ in roadway varies with have the salient features of large deformation, strong ffi the ratio of horizontal lateral pressure coefficient in rheology, high instability, and extreme di culty in [ – ] x-direction and y-direction. Finally, according to the supporting control 2 5 . Among them, the high geostress distribution characteristics of PFZ and range of PFZ and complicated geological structure framework are the under the non-uniformly high geostress, this paper has key factors that cause these problems. As regards the high [ ] [ ] [ ] proposed a combined support scheme, and refined and geostress, Li et al. 6 , Liu et al. 7 ,andLiuetal. 8 optimized supporting parameters. The field monitoring pointed out that the geostress has extremely strong results prove that the roadway deformation and fracture directional characteristics in China by analyzing vast have been effectively controlled. The research results of amounts of geostress data from in situ tests. The lateral ffi ( this paper can provide theoretical foundation as well as pressure coe cient stress ratio of between maximum ) – technical reference for the stability control of deep horizontal and vertical is 0.85 2.63, while the ratio of - broken roadway under non-uniformly high geostress. maximum horizontal principal stress to minimum prin cipal stress is 0.6–2.02. Therefore, it is the foundation of maintaining the stability of deep roadway to grasp the deformation and fracture law of surrounding rock under high, especially non-uniform geostress. * Corresponding author: Yaoguang Huang, College of Sciences, [ ] Center for Post-Doctoral Studies in Safety Science and Engineering, Aiming at this problem, Park and Kim 9 obtained Xi’an University of Science and Technology, Xi’an 710054, the complete stress–strain solution of the circular Shaanxi, China, e-mail: [email protected] roadway subjected to uniform (i.e., horizontal stresses Aining Zhao, Tianjun Zhang: College of Sciences, Xi’an University of are evenly distributed and equal to vertical and can be ’ Science and Technology, Xi an 710054, Shaanxi, China different in each horizontal direction) loading conditions Weibin Guo: College of Energy Engineering, Key Laboratory of ff - Western Mine Exploitation and Hazard Prevention with Ministry of based on di erent deformation criteria in an elasto Education, Xi’an University of Science and Technology, plastic zone and elastic–brittle criterion. Sharan [10,11] Xi’an 710054, Shaanxi, China also obtained the stress fields and displacement fields in Open Access. © 2020 Yaoguang Huang et al., published by De Gruyter. This work is licensed under the Creative Commons Attribution 4.0 Public License. Plastic failure zone characteristics of roadway in the fault area 407 surrounding rocks by using Hoek–Brown’s elastic–brittle Cao et al. [24] enriched and improved this technology criterion. Fahimifar and Hedayat [12] determined the and optimized its support parameters to make it suitable stress states and displacement fields in the rock masses for an extremely fractured roadway. He and Zhang [4] around axisymmetrical excavating circular opening by discovered that the extent of damage to surrounding assuming that all the strength parameters are linear rocks of the roof and floor increased proportionally to functions with plastic shear strain. In addition, under the lateral pressure coefficient under high-level tectonic the assumption of the “Three-zones failure model (i.e., stress, so they proposed a combined control scheme of failure zone, plastic zone and elastic zone)” of the “high strength high pre-tension long bolt + large roadway, Jiang et al. [13] not only concluded the closed diameter high strength anchor cable + yieldable analytical solutions of stresses and deformation by U-shaped steel support + grouting behind the roadway taking advantage of the Mohr–Coulomb criterion and ribs”. Moreover, Cao and Li [5] further pointed out that non-correlated elastoplastic method, but also obtained there is a nonlinear positive correlation between roof– the calculation formulas of the extent of fracture zone floor deformation and lateral pressure coefficients, and and plastic zone in the roadway. These results have laid proposed a scheme of combined arch–beam and support. a theoretical foundation for studying roadway deforma- Zhang et al. [25] put forward the use of reinforced tion and failure. However, since these researches on concrete to support and control roadway under the deep roadway deformation and failure are only carried out and high in situ stress roadway. Furthermore, Duan et al. under uniform loads, their results cannot be used to [26] and Feng et al. [27] proposed the idea and method of study the roadway deformation and failure under deep stability control through in situ observation and me- and non-uniformly high geostress. Therefore, Sun and chanism analysis of damage fracture of surrounding rock Lu [14] and Pan et al. [15] deduced approximate of large chamber under high geostress, making it more analytical solutions of stress, displacement, and radius targeted and reasonable. The results of the above studies in the elastic zone, plastic softening zone, and plastic help to open up new concepts and methods for roadway residual fracture zone of circular roadway under non- deformation and fracture and support under deep and uniform (i.e., horizontal stresses are evenly distributed high geostress. However, these researchers only consid- but different than vertical) loads based on the trilinear ered the condition that the maximum horizontal geostress stress–strain softening model and plastic flow theory, is not equal to the vertical stress, but ignored the which lays a theoretical basis for studying the deforma- influence of non-uniformity of horizontal geostress in tion and fracture law of roadway under deep and high different horizontal directions on the roadway deforma- geostress. On this basis, Li et al. [16] discussed the shape tion and failure, as well as the design and parameter and type of plastic zone in a rectangular roadway with optimization for roadway support, such as length, variable spans under different lateral pressure coeffi- spacing, row spacing, and arrangement of grouting bolt cients by employing Fast Lagrangian Analysis of Con- or cable and so on. tinua in 3 Dimensions (FLAC3D). Ma et al. [17] researched Therefore, in order to acquire the influence of law of the distribution regularity of plastic zone in roadway the difference of horizontal geostress in different direc- under different support schemes with a horizontal lateral tions on the roadway failure, this paper first uses the pressure coefficient of 0.75. Besides, Huang et al. [18] elastoplastic theory to derive analytical solutions of the and Xiao et al. [19], Gao et al. [20] and Yu et al. [21] and stress and range of PFZ in the surrounding rock under Lin et al. [22] studied the roadway deformation and non-uniform geostress, and compares the analytical fracture under different lateral pressure coefficients solutions with numerical solutions obtained by FLAC3D based on the finite element method (for example, software. Second, the numerical simulation method is ADINA-Automatic Dynamic Incremental Nonlinear Ana- used to obtain the stress fields, the distribution character- lysis, COMSOL Multiphysics) and the discrete element istics, and the range of PFZ in the roadway surrounding method (for example, UDEC-Universal Distinct Element rock under high and non-uniformly horizontal geostress Code, PFC-Particle Flow Code), respectively, which (i.e., horizontal stresses are evenly distributed but different provided a numerical simulation reference for the than vertical and can be different in each horizontal roadway support with non-uniform