Stability calculations in jointed rock mass:Dissertation

An isoparametric two dimensional joint element with independent non linear behaviour models for normal and shear stress has been used to study different failure criteria and the accuracy of calculations.Testing of the behaviour models indicated similar results obtained by other researchers with different finite element codes.JRTEMP is the first finite element program which can couple joint elements and thermal loading in plane stress, in plane strain and in axisymmetric cases.Joint normal stress behaviour followed Goodman's (1976) hyperbolic law for normal stress deformation relationship and shear behaviour by Barton's (1977) peak shear strength criterion which is a function of normal stress.All these non linear behaviour models can be used in conjunction with thermal loading produced by solid elements.Joint elements have zero thickness and no thermal properties.The failure criteria were checked at integration points.The state of equilibrium was checked after each iteration in every load step.The stiffness matrix of the whole calculation was reformed at the same time.The examples of this study indicate that by applying non linear model to the behaviour of a joint, at least three integration points should be used.One point integration might produce big differences in displacements compared with results achieved by five point integration.A fluctuating displacement/shear stress effect may also occur