Redistribution and magnitude of stresses around horse shoe and circular excavations opened in anisotropic rock  

作　　者：Mambou Ngueyep Luc Leroy Ndop Joseph Ndjaka Jean-Marie Bienvenu 

机构地区：[1]Laboratory of Material Sciences, Department of Physics, Faculty of Sciences, University of Yaoundé 1 [2]Department of Mine Mineral Processing and Environment, School of Geology and Mining Engineering, University of Ngaoundéré [3]Douala Institute of Technology

出　　处：《International Journal of Mining Science and Technology》2015年第4期615-621,共7页矿业科学技术学报（英文版）

摘　　要：In this paper numerical analysis of underground structures, taking account the transverse isotropy system of rocks, was done using CAST 3M code by varying the shape of excavation and the coefficient of earth pressure k. Numerical results reveal that the anisotropy behavior, the shape of hole and the coefficient of earth pressure k have significant influence to the mining induced stress field and rock deformations which directly control the stability of underground excavation design. The magnitude of horizontal stress obtained for the horse shoe shape excavation(25.2 MPa for k = 1; 52.7 MPa for k = 2)is lower than the magnitude obtained for circular hole(26.4 MPa for k = 1; 59.5 MPa for k = 2).Therefore, we have concluded that the horse shoe shape offers the best stability and the best design for engineer. The anisotropy system presented by rock mass can also influence the redistribution of stresses around hole opened. Numerical results have revealed that the magnitude of redistribution of horizontal stresses obtained for transverse isotropic rock(12.1 MPa for k = 0.5; 25.2 MPa for k = 1 and52.7 MPa for k = 2) is less than those obtained in the case of isotropic rock(27.6 MPa for k = 1;48.6 MPa for k = 2 and 90.81 MPa for k = 2). The more the rock has the anisotropic behavior, the more the mass of rock around the tunnel is stable.In this paper numerical analysis of underground structures, taking account the transverse isotropy system of rocks, was done using CAST 3M code by varying the shape of excavation and the coefficient of earth pressure k. Numerical results reveal that the anisotropy behavior, the shape of hole and the coefficient of earth pressure k have significant influence to the mining induced stress field and rock deformations which directly control the stability of underground excavation design. The magnitude of horizontal stress obtained for the horse shoe shape excavation （25.2 MPa for k = 1; 52.7 MPa for k = 2） is lower than the magnitude obtained for circular hole （26.4 MPa for k= 1; 59.5 MPa for k=2）. Therefore, we have concluded that the horse shoe shape offers the best stability and the best design for engineer. The anisotropy system presented by rock mass can also influence the redistribution of stresses around hole opened. Numerical results have revealed that the magnitude of redistribution of horizontal stresses obtained for transverse isotropic rock （12.1 MPa for k = 0.5; 25.2 MPa for k = 1 and 52.7 MPa for k=2） is less than those obtained in the case of isotropic rock （27.6 MPa for k= 1; 48.6 MPa for k = 2 and 90.81 MPa for k = 2）. The more the rock has the anisotropic behavior, the more the mass of rock around the tunnel is stable.

关 键 词：Horse shoe excavation Stress Strain Transverse isotropy Finite element 

分 类 号：TD311[矿业工程—矿井建设]