A Numerical Study On Propagation And Coalescence Of 3D Cracks Under Triaxial Compressive Loads By Using The General Particle Dynamics(GPD) Algorithm

Rocks in nature is a kind of material by different degree of damage, usually contains defects such as cracks.The initiation, growth and destruction is the basis of the research on instability and damage of rock mass. In recent years, in the field of fractured rock mass extension and failure mechanisms of three-dimensional cracks become an important topic,study on failure process and extension mechanism of rock cracks under three-dimensional stress conditions still further. Therefore, the study of fractured rock mass under triaxial compression conditions of its initiation, expansion and strength of law is very important.Prefabricated three-dimensional cracks in the real rock material and observating the initiation and expansion of internal cracks is very difficult.Some scholars transparent plexiglass material?PMMA? as the similarity of the rock material at low temperatures freezing conditions uniaxial compression test, observed three-dimensional crack initiation, connectivity, propagation law.Based on the numerical simulation method of GPD, study acts of destruction of plexiglass?PMMA? specimens containing three-dimensional flaws under uniaxial compression, triaxial compression and true triaxial compression. Specific work and conclusions are as follows:?1?Under the condition of uniaxial compression, study behaviors of crack initiation, connections, expansion in plexiglass specimens containing three-dimensional flaws. Analyze the influence of the non-overlapping length on nitiation,propagation of cracks and peak stress of the specimen.?2?Study behaviors of crack initiation, connections, expansion in plexiglass specimens containing three-dimensional flaws under triaxial compressive loads. Analyze the influence of the confining pressures on initiation,propagation of cracks and peak stress of the specimen. Crack initiation stress and peak stress of the specimen increased with the increase of confining pressure,.?3? Study behaviors of crack initiation, connections, expansion in plexiglass specimens containing three-dimensional flaws under true triaxial compressive loads. Analyze the influence of the intermediate principal stress on initiation,propagation of cracks and peak stress of the specimen. Crack initiation stress and peak stress of the specimen increased with the increase of the intermediate principal stress. Residual strength of specimens shows an increasing trend. Although the simulation range of intermediate principal stress has not yet reached ?₂=?₁, the trend has emerged,which with the increase of the intermediate principal stress the peak stress increases firstly and then decreases.?4? Under the condition of triaxial compressive loads and true triaxial compressive loads, analyze the influence of the non-overlapping length on crack propagation and peak stress of the plexiglasss pecimens containing three-dimensional flaws.