Experimental Study And Particle Flow Simulation On Mechanical Properties Of Yellow Sandstone With Different Bedding Angles

Yellow sandstone is a kind of sedimentary rock.Due to the difference in deposition time and sediments,a series of bedding surfaces will be formed,which will have a certain impact on the overall mechanical properties of the rock.In actual engineering such as coal mining and chamber excavation,bedding yellow sandstone is a frequently encountered engineering rock mass.After a long period of geological action,the inner bedding surface of yellow sandstone has undergone different changes in its occurrence and intensity.As a structural weak surface,it seriously affects the mechanical properties of yellow sandstone and often causes the instability and destruction of engineering rock masses.Therefore,in this thesis,the mechanical properties and failure mechanism of yellow sandstone which are changed with inclination angle and confining pressure are studied by means of indoor experiment and numerical simulation.The main research contents are as follows:(1)Prepared yellow sandstone specimens with different bedding angles and performed conventional triaxial compression tests with 5 kinds of confining pressures.At the same time,the real-time acoustic emission monitoring system is used to monitor the response of acoustic emission events.The influence of bedding angle on the strength characteristics of yellow sandstone under triaxial compression is analyzed.and the deformation and failure mechanism of bedding sandstone under different confining pressures is revealed.(2)Set loading plan based on conventional triaxial test results.Performed triaxial cyclic loading and unloading tests on yellow sandstone specimens with 4kinds of bedding angle under 5 kinds of confining pressures.Analyzed the influence of the bedding angle on the strength,deformation characteristics and failure modes of yellow sandstone under the cyclic loading and unloading path.From the energy point of view,the damage evolution law of yellow sandstone specimens during cyclic loading and unloading is explored.(3)Constructed model specimens with bedding in the discrete element particle flow software PFC^2D.According to the results of the indoor test,selected the appropriate mesoscopic parameters,and carried out conventional triaxial compression test simulation and cyclic loading and unloading compression test simulation of specimens with different bedding angles.The simulation results and laboratory test results are compared and analyzed,and the evolution law of the microscopic cracks of the sample is explored,and the failure mechanism of yellow sandstone under different loading paths is revealed from the perspective of micromechanics.There are 66 figures,6 tables and 99 references in this thesis.