Study On Damage Constitutive Model Of Rock With Fracture

The strength and deformation of rock is a classic subject of rock mechanics,and it is also one of the hot issues in current research.This article focuses on rock deformation issues.At the same time,the cracks filled in the rock material have a great influence on the mechanical properties of the rock.When establishing a mathematical or mechanical model reflecting the rock deformation process,the influence of the crack should be considered.Based on the simulation of rock deformation curve,this paper has carried out research work on the following aspects: one is the mathematical simulation of the axial stress-strain curve of intact rock or meso-fractured rock;the other is the line mathematical simulation of the axial stress-strain curve of macro-fractured rock;the third is the mathematical simulation of the stress-strain curve of the layered fractured rock.A variety of mathematical mechanics models have been established from different aspects to simulate the whole process deformation curve of rock.The main research results are summarized as follows:(1)Summarized the general framework of the damage constitutive model of intact rock or meso-fractured rock by the phenomenological damage method.Established the statistical model of rock damage through the statistical growth curve model.By the knowledge of probability theory,the phenomenological damage model which fully reflects the deformation stage of the rock peak is established.Discussion has been made on the closed phase in the rock deformation stage.Combined with the fractional calculus theory,the phenomenological damage model of rock dynamic deformation is established.The above models are close to the experimental values,which can better restore the axial stress-strain curve of the rock.(2)A damage constitutive model of meso-fractured rock is established from a mesoscopic perspective.Based on the Ashby model,a new rock meso-damage constitutive model is obtained by modifying the metrics of macro-damage variables and meso-damage variables.The model calculation curve agrees well with the test curve.Combined with meso-fracture mechanics,considering the micro-fracture expansion process,a meso-fracture constitutive model for rock deformation curve simulation is established.The model also fits well with the test curve.(3)A similar rock-like material was prepared,and a single-slit rock uniaxial compression test was carried out.The influence of crack inclination on rock strength was analyzed.The calculation of the macroscopic damage variable of rock is discussed.The difference between the coupling modes of two different macroscopic and mesoscopic damage variables is compared mathematically.A damage constitutive model with macroscopic and mesoscopic fractured rock is established by fitting method and coupling modes of macroscopic and mesoscopic variable.The calculation results show that the damage constitutive model established by the fitting method is more in line with the experimental data for the data of this test.(4)The triaxial compression test of layered rock and the uniaxial compression test of fractured layered rock were carried out,and the test results were briefly analyzed.The equivalent deformation parameters of layered rocks are calculated by Salamon method.The damage constitutive model of layered rocks is established.According to the coupling of macroscopic and mesoscopic damage variables,the damage constitutive model of fractured layered rocks is established.The calculation results of these models are in good agreement with the test.At the same time,the rock damage constitutive model under true triaxial conditions and the simulation method of transverse stress-strain curve and volumetric strain curve are also given.(5)Several application problems related to rock damage theory are discussed: the application of damage perspective to simulate creep curves and circular tunnel stress calculation problems.In the creep simulation part,it is found that the three stages of creep can be better reflected by the viewpoint of damage,in the calculation of the stress of the circular tunnel,based on the viewpoint of damage mechanics,the difference between the tunnel stress calculated by various strength criteria and the maximum bearing capacity of rockburst is compared.It indicates that the selection of the strength criterion has a great influence on the stress distribution of the tunnel.