Research And Numerical Simulation Of Triaxial Compression Performance Of Layered Composite Rock

With the continuous development and utilization of underground resources,the study of deep layered composite rocks has attracted the attention of many scholars.Layered composite rock is located in the complex environment of high stress and multi coupling field,which is composed of different thickness and mechanical properties of rock by different combination methods.Compared with single rock,layered composite rock has complex properties,which brings many difficulties to the design and construction of deep underground engineering.In order to further study the mechanical properties of the layered composite rock in depth,this paper artificially made a layered composite rock composed of three single rocks of white sandstone,red sandstone,and blue sandstone,with settings of 0°,15°,30°,and 45°.Four types of interface layer inclination angles,and the distance between the interface layers are 10 mm,15mm and20 mm respectively.Uniaxial and conventional triaxial compression tests and theoretical analysis have been carried out on rock samples corroded by common conditions and chemical solutions;On the basis of the experiment,the use of scanning electron microscope was used to analyze the failure interface of the specimen.The failure process of the rock sample was simulated by finite element software and the change of elastic strain energy during the experiment was analyzed.The main research contents are as follows:(1)With white sandstone,red sandstone,and blue sandstone as the base rock,layered composite rocks with different dip angles and different interlayer spacings were produced,and uniaxial and conventional triaxial compression tests of layered composite rocks were carried out,and various tests were carried out.Analysis of mechanical properties and failure modes of parts,analysis of the influence of inclination angle,layer spacing and confining pressure on the test results.(2)The test of the influence of acid corrosion on the strength of layered composite rock was carried out,and the changes of mechanical parameters under the acidic environment with different ordinary conditions and concentrations were analyzed.The results showed that under the acidic environment of p H=2 and p H=4,the acidic environment The compressive strength of the rock sample is significantly reduced,and it decreases as the p H value decreases.(3)Using SEM electron microscopy technology to scan the damaged rock sample and observe the failure interface of each constituent rock sample,obtain the development of interfacial cracks of each component,and explore the strength of each part of the rock sample.The results show that red sandstone has the highest strength,followed by blue sandstone,and white sandstone is the smallest.Using image processing software,the hole ratio and crack length of each part of the rock are analyzed,and the failure trend of the rock sample is proved from a meso-level perspective.(4)The elastoplastic theory is used to analyze the mechanical response of the specimen,and it is found that the external stress and strain of the rock boundary plane and the rock boundary plane are quite different;the Mc Lamore-Gray strength criterion is used to compare the experimental values with the theoretical values,the results confirmed a high degree of agreement.(5)Models with different confining pressures,different dip angles,and different interlayer spacings were established using ANSYS software to simulate the elastic strain energy released by the rock sample during the test process,and the influence of the above factors on the change and distribution of energy was analyzed.The results showed : The change of energy is closely related to the confining pressure,the inclination angle,and the size of the interlayer spacing.