Acoustic Emission Features And Cracking Mechanism Of Layered Composite Rock–like Material

The special geological body of layered composite rock is widely distributed in nature,since the long and complicated geological process of earth.These layers are often made up of alternating layers of different lithologies that are very tightly bound.Macroscopically,it presents the characteristics of discontinuity,anisotropy and high heterogeneity.The mechanical properties are not only affected by the properties of the matrix materials of each layer,but also the thickness of each layer,the inclination of the layer,and the state of stress are also crucial to the safety and stability of rock mass engineering.Therefore,it is of great theoretical and practical significance to study the mechanical properties and failure mechanism of layered rock mass.The main research work is as follows:(1)In this paper,ordinary Portland cement,quartz sand and plaster of paris were used,and two similar materials with different mechanical properties were prepared through a series of ratio tests.Then the two similar materials were made into a single rock sample and used for uniaxial compression tests under different rate loading conditions to study the basic mechanical properties of homogeneous rock materials;(2)This article studies the methods of drilling and processing samples with different rock dip angles.For this purpose,a mold specially designed for processing rock samples of layered composite rock formations is specially designed.The layered composite strata-like rock samples composed of these two materials with different mechanical properties and similar are produced.The samples are divided into two groups of different layer thickness ratios,and each group of samples has seven different rock inclination angles.(3)Conventional uniaxial compression tests of layered composite rock samples with different bedding dip angles have been carried out in this paper.The acoustic emission parameters and crack propagation process of the sample surface were recorded.The stress-strain curve,strength and deformation characteristics,acoustic emission characteristics and crack mode of different dip angles were compared and analyzed.(4)In this paper,with DIC digital speckle system and acoustic emission system in different conditions and different loading rate than with a thick layer of laminated composite class conventional uniaxial compression test of rock specimen,analysis of different loading rate affects the lower composite rock sample broken process,explore the loading rate and layer thickness ratio on layered composite models of broken rock materials.(5)Based on particle flow PFC2 D,macroscopic strength of mesoscopic parameters calibration in different aspect Angle of layered composite rock indoor conventional uniaxial test numerical simulation analysis,comparison and analysis of numerical and experimental model of macroscopic strength and destroy model,and studied the model of the shear crack evolution process with the macro mechanical strength.(6)Summarizes the fracture evolution mechanism of layered composite rock materials with different layer inclination angles,loading rates,and interlayer thickness conditions.