Research On Mechnical Behavior.Of Jointed Rock Mass Based On Smooth-joint Contact Model

Rock mass is a complex geologic body cut by structural planes,occurred naturally through geological processes during long geologic history.The bedding planes of rock masses have a significant effect on the strength,deformability,and the stability.The rock masses are featured as discontinuous,non-elastic,and anisotropic in nature,largely due to the mechanical properties varied greatly different between structural planes and intact rock.This difference determines the internal geometry of jointed rock mass.Therefore,an adequately capture and characterization of geometric and mechanical properties of structural plans is an important prerequisite for conducting rock mass engineering and research.At present,research on mechanical behavior of jointed rock mass includes laboratory experiments,theoretical analysis and numerical modeling.Laboratory experiments usually adopt similar material model which is deferent from natural jointed rock mass specimen.Theoretical analysis is based on certain simplifications and assumptions,resulting in great limitations.Numerical modeling,which overcomes shortcomings of the above methods to some extent,has been widely used to simulate the mechanical behavior of jointed rock mass and conduct stability computation of rock mass engineering.As a typical discontinuous modeling approach,particle flow method possesses outstanding advantage in studying the mechanical behavior of jointed rock mass.By using particle flow code PFC3D,this paper adopts bonded-particle model(BPM)and smooth-joint contact model(SJM)to represent intact rock and joint,respectively.A systematic parametric study of smooth joint on the macro properties of jointed specimen containing a single joint and the anisotropy of strength and deformation of layered rock mass specimen.The main accomplishments of this research include as the followings:(1)Unboned joint and bonded joint is simulated using SJM.A parametric study of smooth joint is conducted on rock mass specimen containing a single joint via triaxial compression test to explore the effects of each micro mechanical parameters of smooth joint on the strength,deformation and failure process of specimen.(2)An effective calibration method is proposed based on the influence degree of different micro mechanical parameters of smooth joint.By adopting the proposed calibration method,a set of proper micro parameters for SJM is selected to reproduce the laboratory experimental results.(3)Seven layered rock models with different joint orientations are established to investigate the effects of micro mechanical parameters of smooth joint on the anisotropy of strength and deformation of layered rock mass specimen via uniaxial compression test.Micro mechanical parameters of smooth joint is then calibrated against laboratory experimental results.Also,theoretical analysis is presented to verify the validity of both numerical and experimental results.(4)Further analysis from the micro perspective is carried out by observation of the transmission of contact force,distribution and type of micro cracks,particle displacement,and compared to laboratory experimental results,which explore the propagation of cracks and ultimate failure modes...