Research And Application Of Layered Rock Simulation Based On Cosserat Continuum Theory

Layered rock structure is one kind of the main rock structures. Layered rockunder load is very prone to slide along the occurrence plane, thus causing the rockbent. Traditional numerical simulation methods do not consider the ability of rock toresist bending and deformation, resulting in a great difference compared to actualsituations. Cosserat continuum theory is focused on media that has micro-structure.Within a certain characteristic scale, it allows rock to bear stress and deformationunder the external loads. In this paper, research and application of simulation methodbased on the Cosserat continuum theory of layered rock masses are carried out, whichaims at the deformation and failure characteristics of the layered rock structure.The main content of this dissertation is as follows:(1)By referring to the planar four node isoparametric element, the shape functionexpressions, the strain matrix, the elastic-plastic matrix, stiffness matrix—AMATRXand residual loading matrix—RHS, which are needed in the Cosserat medium elementconstruction process are given. UEL (User Subroutine to define an new element type)of Cosserat medium element is developed based on ABAQUS.(2)Subroutine of Finite Element Method based on Cosserat continuum theory isverified with its deformation and strength characteristics. With numerical simulationof a cantilever beam which is under uniformly distributed load and composed oflayered rock, the ability to reflect the bending effect of the subroutine is verified. Theinfluence on material deformation caused by shear stiffness and spacing changes ofstructural plane through the axial compression tests is studied. The subroutine’s abilityto reflect the intrinsic scale of the media is then proved. A numerical simulation of theclassical theory of Jaeger proves the subroutine’s ability to reflect the strength oflayered rock mass.(3)With the help the developed subroutine, numerical simulation is taken outalong forward, steep dip and anti-inclination direction etc.—the three main layeredstructure slope. The results of different deformation characteristics and failure modesof slope under different inclination conditions are compared with the results obtainedby Jointed Element Method. In light of the fact that Cosserat continuum theoryintroduces the couple stress which can reflect the stress gradient in the cell body andtake into account the flexural rigidity of the unit, it is better to reflect the bendingdeformation and failure characteristics of layered structure slope. By comparing andanalyzing the two different numerical simulation methods, it is proved that thedeveloped subroutine of Cosserat continuum theory can simulate shear slip, buckling,bending to the dumping and other failure modes of layered rock more efficiently.