Research On Numerical Simulation Of Fracture Of Rock Mass Under Compression Based On The Strain Softening Model

Many works have been done by many experts and scholars in related fields to study the initiation and propagation mechanism of rock mass fractures and the failure process of rock mass.As we know,the failure of many rock mass projects has a certain relationship with its internal joint or fissure propagation or penetration.It's difficult to capture the fissure propagation law since rock mass is a complex material with discontinuous and non-uniform characteristics and rock mass fissure propagation theory is not perfect.Moreover,when people use specimen made by the real rock mass for fracture test,it is difficult to observe the fissure propagation process in the rock mass for the limitation of the observation means.But numerical test analysis can overcome the disadvantage mentioned above,scholars can use numerical simulation toobtain the law of fissure propagation in their study.At present,FLAC3 D code has been used by many scholars to analyze the process of crack propagation in rock mass and the rock mass' s constitutive models are usually dominated by Mohr-Coulomb model when they do a related research.It can be found that the fissure front region shows a large plastic zonefrom the simulation results and it is difficult to get the pictures and relationships like propagation state or the running-through process of the new fracture.Therefore,it is necessary to select a more suitable constitutive model to analyze the fissure propagation process.The main contents of this dissertation are as follows:(1)The classification of fractures in rock mass and the basic theories of fissure propagation in fracture mechanics are introduced.(2)The stress-strain curve is simulated under the uniaxial compression test of fractured rock mass with FLAC3 D code.In the study,the basic theory of strain softening constitutive model in the software is introduced.Then uniaxial compression test of fractured rock mass with different inclination angles has been done with two different ways when the two different models which represent the nature of the rock mass– one is the Mohr-Coulomb model,and the other is the strain softening model,both of which are included in constitutive models of FLAC3 D code.By comparing and analyzing the results from the numerical simulation,we find that the strain softening model is more suitable to study the fissure propagation.(3)Based on the strain softening model in FLAC3 D code,the compression test is done to study the fissure propagation of the jointed rock mass.By choosing the fissure length,inclination,spacing,distance,number and confining pressure as independent variables,this dissertation mainly discusses how these independent variables impact the fissure propagation and rock mass peak strength.Moreover,the applicability of the above model is compared and analyzed by using relevant experimental results in the literature.