Study On The Black Shale Microfabrication Characteristics And Expansion Characteristics In Chengkou Area Of Northeast Chongqing

At this stage,there is little research on the swelling characteristics of black shale after encountering water,especially from the micro-macro level.Therefore,this article uses XRD phase analysis instrument,XRF chemical element testing instrument,scanning electron microscope SEM,etc.to analyze the phase,interlayer spacing,interlayer expansion force and micromorphology of the black shale from the microscopic layer.At the same time,the black shale three-dimensional expansion force test was carried out,and then the microscopic expansion stress and the macroscopic expansion stress were connected to establish a micro-macroscopic expansion constitutive model,and finally the MATLAB software was used to verify the established expansion model.Its main research content includes the following aspects:(1)Use the JADE software to analyze the XRD diffraction pattern of the unsoaked black shale and measure its mineral content.Using MATLAB to make partial enlarged 3D images of samples No.3 and No.6,through analysis of the diffraction angle 2? of 45.39 °,the change of the main peak when soaked for 5d,10 d,20d,30 d compared with the initial value,sample No.3 Increased by 7.98%,19.72%,31.51%,70.92%,sample No.6 increased by 5.55%,16.07%,21.76%,61.88%.Further analysis found that with the increase of the immersion time,the internal mineral composition of the sample was increased between the interlayer spacing and the expansion force of the crystal layer.MATLAB software was used to obtain the intercrystalline spacing and the expansion force of the crystal layer with the increase of the immersion time.The fitting function of t.(2)The original three-dimensional swelling force test of black shale shows that in three different solutions,the growth rate and maximum stress of the black shale are different;the expansion stress in the axial F1 direction is relative to the lateral F2,The expansion stress in the F3 direction is greater.Combined with the XRD test to measure the content of the corresponding clay minerals in the black shale,the fitting formula of the original expansion force of the black shale considering the clay mineral content is obtained.(3)At the granular level of clay mineral expansion force,from the micro to macro process,since the rock mass structure is a spatial continuum,the generation of micro expansion to macro expansion force is defined as three stages,and the micro to The mechanism diagram of macroscopic expansion force.On the repulsion level of the electric double layer between the crystal layers,based on the research foundation of the predecessors,a schematic diagram of the expansion of the electric double layer repulsion between the crystal layers was made.(4)Combining the microscopic expansion force of clay minerals and the growth time function of the interlayer spacing,combined with the original three-dimensional expansion test of black shale,the expansion constitutive model of black shale is derived and verified by MATLAB software.