Modification And Engineering Application Of Drucker-Prager Strength Criterion Based On Releasable Strain Energy

The Drucker-Prager strength criterion(D-P strength criterion)considers the influence of the principal stress and hydrostatic pressure,and there is no sharp point problem,so it is widely used in the numerical calculation of geotechnical engineering.However,the D-P strength criterion has some disadvantages,such as large tensile-shear zone and no stress angle effect.Although scholars at home and abroad have revised the D-P strength criterion from different angles and improved its calculation accuracy,these revisions still have varying degrees of limitations.Therefore,in view of the deficiencies of the D-P strength criterion,the D-P strength criterion was revised from the perspective of releasable strain energy,and the revised D-P strength criterion(GD-P strength criterion)was embedded in the Flac3D6.0software for stability analysis based on the C++ program.The main conclusions are as follows:(1)According to the first law of thermodynamics,it is analyzed that the root cause of the shortcomings of the D-P strength criterion is that the Poisson's ratio is regarded as 0.5 when the material yields(damages).(2)Based on the fact that energy conversion is the essential attribute of the physical process of matter,it is proposed that when the releasable elastic strain energy reaches a certain critical value,the material will begin to yield(damages),so as to establish GD-P strength criterion that can solve the problem of large tension-shear zone and lack of stress angle effect.(3)Theoretical analysis shows that the GD-P strength criterion is the inheritance and development of the D-P strength criterion.The criterion is a set of strength criteria with Poisson's ratio as a parameter.The yield(damages)trajectory in the ?plane is a cluster of concentric circles.When the rock yield(damages),the Poisson's ratio is 0.5.This criterion is transformed into the D-P strength criterion;This criterion reflects the influence of the stress level on the Poisson's ratio when the rock yield(damages).When multiple Poisson's ratios are used for calculation,the problems of large tension-shear zone and no stress angle effect of D-P strength criterion can be effectively solved.(4)The GD-P strength criterion is verified by the true triaxial test results of four kinds of rocks,and the calculation results show that its calculation accuracy is higher than D-P strength criterion and M-C strength criterion.(5)Based on the ideal elastic-plastic model,taking GD-P strength criterion as shear yield function and considering tensile failure,it is embedded into Flac3D6.0software for numerical calculation based on C++,and the correctness of the constitutive model is verified by triaxial test.The application of GD-P model in underground engineering is analyzed by a classical underground cavity model,and compared with D-P strength criterion and M-C strength criterion.the results show that the calculation results of GD-P strength criterion(?= 0.48)are safer than D-P strength criterion and M-C strength criterion.