Abstract
In this work, an anisotropic constitutive model of hexagonal columnar jointed rock masses is established to describe the distribution law of deformation and the failure of columnar joint caverns under anisotropic conditions, and is implemented to study the columnar jointed rock mass at the dam site of the Baihetan Hydropower Station on the Jinsha River. The model is based on the Cosserat theory and considers the mesoscopic bending effect on the macroscopic mean. The influences of joint plane inclination on equivalent anisotropic elastic parameters are discussed via the introduction of an off-axis transformation matrix and the analysis of an example. It is also pointed out that the six-prism columnar jointed rock mass changes from transverse isotropy to anisotropy under the influence of the angle. A numerical calculation program of the Cosserat constitutive model is developed and is applied to the simulation calculation of a Baihetan diversion tunnel to compare and analyze the respective plastic zones and stress distributions after tunnel excavation under both isotropic and anisotropic conditions. The results reveal that, compared with the isotropic model, the proposed Cosserat anisotropic model better reflects the state of stress and asymmetric distribution of the plastic zone after tunnel excavation, and the actual deformation of the surrounding rock of the tunnel is greater than that calculated by the isotropic method. The results aid in a better understanding of the mechanical properties of rock masses.
Highlights
With the development of many water conservancy and hydropower projects in southwest China, the columnar jointed basalt located in the development area of the Baihetan Hydropower Station on the Jinsha River has attracted the research interest of many domestic scholars [1,2,3,4,5]
When the cylinder is deflected by 15◦, anisotropic constitutive model, a numerical calculation program with multiple sets of joint surfaces considering the influence of the off-axis condition, and compared with the positive axis, E3 is reduced was developed to investigate the deformation and failure of a columnar jointed rock mass tunnel by 21.2%, E2 is reduced by 5.1%, and Poisson’s ratio and shear modulus change by varying degrees
Combined with the primary calculation methods of FLAC3D, the Cosserat anisotropic constitutive model was programmed by VC++ and compiled into the dynamic link library (DLL file), and was embedded in the software to carry out the calculation of the columnar jointed rock mass
Summary
With the development of many water conservancy and hydropower projects in southwest China, the columnar jointed basalt located in the development area of the Baihetan Hydropower Station on the Jinsha River has attracted the research interest of many domestic scholars [1,2,3,4,5]. Et al [20] established a transverse isotropic constitutive model for masses columnar into account in the jointed layer, the column deflection, and column other factors. Deducedmodel an anisotropic constitutive model of columnar jointed rock masses viaThese the theory of fracture energy. For the excavation of a chamber the influencing factors; its applicability is reflected on the basis of mechanical properties and in a jointed rock mass, the conventional equivalent continuous theory fails to consider the influence geological engineering the excavation of a chamber inmechanical a jointed rock mass, the conventional of local bending stress, laws. A three-dimensional research the jointed mass isas regarded as an equivalent and a threeCosserat constitutive of themodel regular rock jointed mass isrock established.
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