Research On MC Strength Criterion Based On Energy Mechanism And Its Applicatio

Rock mass is a heterogeneous and anisotropic discontinuous material,and the study of its mechanical properties is relatively complex.The Mohr Coulomb strength criterion（hereinafter referred to as M-C）is a widely used and experienced strength criterion in geotechnical engineering.Based on this,since energy conversion is an essential attribute of physical process of matter,based on the generalized M-C strength criterion of elastic strain energy,the energy type generalized M-C rock mass strength criterion（referred to as EGM-C strength criterion for short）is established,and the singular points existing in its Pi plane yield trajectory are corrected.At the same time,the EGM-C strength criterion is embedded into FLAC3D software and simulated to verify the applicability of the criterion.The main achievements are as follows:（1）Based on the release of releasable strain energy is the internal mechanism of rock mass failure,research shows that the M-C strength criterion only considers the influence of deviator elastic strain energy on rock failure,and ignores the influence of tensor elastic strain energy,which may lead to the inconsistency between the physical meaning of the M-C strength criterion and the internal mechanism of rock failure（yield）,which may be one of the reasons for its application scope and calculation accuracy to be improved.（2）Although the generalized M-C strength criterion of elastic strain energy has a high calculation accuracy for true triaxial test data of intact rock,whether it can be directly applied to rock mass is unknown.Based on this,based on the generalized M-C strength criterion of elastic strain energy and the establishment method of H-B rock mass strength criterion,the geological strength index（GSI）and rock mass integrity coefficient K_V are introduced,and the energy type generalized EGM-C rock mass strength criterion is established,which can be applied to both rock and rock mass.（3）The theoretical analysis of the EGM-C strength criterion shows that:（1）when the rock integrity coefficient K_V is equal to 1,the criterion transforms into the GM-C strength criterion;When the rock integrity coefficient K_V is equal to 1 and the material deformation parameterv_mc is equal to 0.5,this criterion transforms into the M-C strength criterion.The EGM-C strength criterion is the inheritance and development of the GM-C strength criterion and the M-C strength criterion,and is a set of strength criteria based on the material deformation parameterv_mc and the rock integrity coefficient K_V,rather than a single strength criterion;（2）The EGM-C rock mass strength criterion can be fully applied to the actual engineering by using the research results of the existing M-C strength criterion.（3）Four groups of rock mass test data validation results:EGM-C strength criterion and L Y.The calculation values of the generalized three-dimensional H-B rock mass strength criterion proposed by Zhang are similar,and the average error accuracy of the EGM-C strength criterion is within 10%.（4）The ellipse corner model is used to eliminate the singularity of the yield trajectory on the Pi plane of the EGM-C strength criterion,and then the improved EGM-C strength criterion（EWM-C for short）is established.From the Pi plane yield trajectory comparison diagram,the Pi plane yield trajectory of the EWM-C strength criterion can maintain complete smoothness and convexity,and its calculation accuracy and applicability are improved to a certain extent through the data validation of the true triaxial test of red sandstone.（5）Based on the C++programming language,the DLL file is compiled and the EGM-C constitutive model is embedded into the finite element software and successfully called.A slope model with a slope height of 30 m and no slope support is established in the finite element software.The M-C constitutive model and the EGM-C constitutive model are used for comparative analysis.The results show that the stress and plastic deformation area of the M-C constitutive model and the EGM-C constitutive model are roughly similar,but the displacement calculated by the EGM-C constitutive model and the M-C constitutive model are 8.6318 cm and 4.6117 cm,respectively.The results calculated by the EGM-C constitutive model are more safe,which may be related to the EGM-C constitutive model considering the rock mass integrity coefficient and material deformation parameters.