Numerical Simulation Of Mechanical Properties Of Jointed Rock Mass Based On Barton-Bandis Joint Strength Criterion

The stability of rock mass in underground engineering has always been a hot topic in the field of rock mechanics and engineering.The natural rock mass is usually cut by a series of joints with different scales to form relatively independent rock blocks.The existence of these joints has a great influence on the mechanical properties of rock mass and the excavation of underground engineering.Due to the influence of many factors such as size effect,observation limitation and fabrication error,it is difficult to observe the exact failure process and failure rule of rock specimen,and it is also difficult to make specimens with different joint parameters.Therefore,numerical simulation has become an important means to study the failure process of jointed rock mass and support design.At present,many scholars have carried out more in-depth research on the mechanical properties of jointed rock mass,but most of the numerical simulation is based on the jointed rock mass with regular joint length and spacing,and the traditional constitutive model cannot reflect the discontinuity problem of non through joint very well.At present,many scholars have carried out more in-depth research on the mechanical properties of jointed rock mass,but most of the numerical simulation is based on the jointed rock mass with regular joint length and spacing,and the commonly used Mohr Coulomb cannot well reflect the discontinuity of all non through joints.Therefore,in this paper,phase~2 finite element software code,which is easy to operate and can define joint parameters independently,is used to study jointed rock as discontinuities.The main research contents and conclusions are as follows:(1)The common theories of jointed rock mass are summarized and analyzed,including the classification,characteristics and failure modes of jointed rock mass.(2)The main strength theories in jointed rock mass are summarized and analyzed to understand the advantages and disadvantages of each strength theory,and according to the research content of this paper,the appropriate strength criterion Barton bandis is selected.(3)This paper introduces the stress-strain curve and failure mode of jointed rock mass under uniaxial compression,and uses phase ~2 finite code software to carry out numerical simulation and analysis on eight working conditions under different joint geometric parameters and joint mechanical parameters,and compares the influence of different joint geometric parameters and mechanical parameters on the strength of jointed rock mass.The joint strength decreases with the increase of joint angle,spacing,length and number,and increases with the increase of joint roughness coefficient,joint wall compressive strength and residual friction angle.Finally,the related experiments in the existing literature are simulated,and the results are compared with the simulation results,which shows the applicability of Barton-Bandis criterion.(4)Referring to the actual engineering example,the paper makes a simplified simulation of the actual engineering example and analyzes the influence of different mechanical parameters on the displacement and deformation of the surrounding rock of the tunnel,with the increase of joint roughness coefficient,compressive strength of joint wall and residual friction angle of joint,the displacement of tunnel surrounding rock decreases and the strength increases.