Application Research On Compression-shear Failure Model Of Rock Considering Non-consecutive Joints

In geotechnical engineering,rock is a very common material.In view of some unique complex properties of rock materials,rock has become the inevitable research object of many experts and scholars.In some rock engineering,such as slope,tunnel and so on,there are all kinds of engineering problems to be solved.In the actual engineering,most of the rock mass is uneven and discontinuous,and there are joints and fissures in the rock.Under the load,these defects have a great impact on the stability of the engineering rock mass,which will directly affect the normal use of the project,and the widely distributed joints and fissures in the rock also bring great difficulties to determine its stress-strain relationship.Therefore,how to reasonably evaluate the stability of rock mass with internal defects has become one of the researches focuses in the field of geotechnical mechanics and engineering.More and more experts and scholars are concerned about the complex characteristics of rock mass.A large number of experimental studies have shown that the failure of rock mass is progressive.With the continuous exploration of scholars,we can know from some established constitutive models of rock materials that many numerical models divide the mechanical behavior of rock materials into several stages,and the mechanical properties of each stage are different.From the phenomenological point of view,the different stages are mainly due to the progressive failure of rock mass.Therefore,based on Eshelby's equivalent inclusion theory,elastic-plastic theory and continuous damage theory,the following work is carried out in this paper:(1)In this paper,the rock mass with non through joints is studied.Compared with the complete rock mass,the stiffness of the rock mass with non through joints will be reduced.In this paper,by using meso mechanics of materials and introducing Eshelby's equivalent inclusion theory,it is considered that the discontinuous joint is included in the rock mass as an ellipsoid inclusion.In this way,the modeling and calculation trouble caused by a large number of discontinuities can be eliminated,and the rock body can be regarded as a macro uniform material,so as to calculate and solve the equivalent elastic modulus expression of rock mass with non through joints.(2)The deformation and failure mechanism of rock mass with non through joints under load is studied.Based on the failure process and failure mechanism of rock mass with non through joints,combined with the derived equivalent modulus theoretical formula,the localized shear band in the failure process of rock mass is simulated by chain model,and the micro characteristics in the process of localized progressive failure of rock mass are studied,which is connected with the macro mechanical behavior and properties of rock mass.In the study of progressive failure process of rock mass,the rock mass specimen is divided into elastic deformation zone and localized shear zone.The shear localization factor and the shear failure factor are defined by the shear displacement and deformation of the specimen.Finally,the constitutive model of rock mass with discontinuous joints under compression shear failure is established.(3)By using the established rock mass compression shear failure model,the theoretical calculation of granite with non through joints under different confining pressures is carried out,and its mechanical behavior in conventional triaxial test is predicted,and then compared with the existing test results.According to the progressive failure characteristics of specimens under compression and shear conditions,the correctness and applicability of the compression and shear failure model of rock mass with non through joints derived in this paper are verified.Comparing the prediction results of the model with the experimental results,the results are consistent,and the more accurate compression shear failure model of rock with non through joints can be further studied.(4)Through the calculation and analysis of practical engineering cases of rock slope,the model is applied to the calculation of safety factor,and the influence of non through joints on safety factor is considered to further verify the feasibility of the theoretical model and formula.