Discontinuity (geotechnical engineering)

About: Discontinuity (geotechnical engineering) is a research topic. Over the lifetime, 4517 publications have been published within this topic receiving 90201 citations. The topic is also known as: joint.

Stress Fracture Criteria for Laminated Composites Containing Stress Concentrations

Abstract: Two related criteria based on stress distribution are presented for predicting the uniaxial tensile strength of laminated composites containing through the thickness discontinuities of a general shape. The criteria result in two parameter (unnotched tensile strength and a characteristic dimension) models which are capable of predicting observed discontinuity size effects without resorting to classical concepts of linear elastic fracture mechanics. As a direct consequence of the stress criteria, however, a relationship between Mode I fracture toughness and unnotched laminate tensile strength is determined. Limited comparison of theory to experimental data for circular holes and straight cracks yields good results. The simplicity of the analytical approach coupled with its generality make it of practical value to the designer.

On discontinuous plastic states, with special reference to localized necking in thin sheets

Abstract: Permissible discontinuities of stress, velocity, and surface slope are investigated in a plastic-rigid sheet deformed in its plane. One such discontinuity of velocity is shown to be the mathematical idealization of localized necking; the necessary restrictions on the stress-state and rate of workhardening are obtained for any yield function and plastic potential. The results are illustrated by an examination of the modes of necking in notched tension strips. The constraint factors at the yield point are obtained for notches with wedge-shaped or circular roots.

Post-Perovskite Phase Transition in MgSiO3

Abstract: In situ x-ray diffraction measurements of MgSiO3 were performed at high pressure and temperature similar to the conditions at Earth9s core-mantle boundary. Results demonstrate that MgSiO3 perovskite transforms to a new high-pressure form with stacked SiO6-octahedral sheet structure above 125 gigapascals and 2500 kelvin (2700-kilometer depth near the base of the mantle) with an increase in density of 1.0 to 1.2%. The origin of the D″ seismic discontinuity may be attributed to this post-perovskite phase transition. The new phase may have large elastic anisotropy and develop preferred orientation with platy crystal shape in the shear flow that can cause strong seismic anisotropy below the D″ discontinuity.

A Model for the Mechanics of Jointed Rock

Abstract: The representation of discontinuities in analysis of blocky rock is discussed. A linkage type element is developed for addition of rock joint stiffness to the structural stiffness matrix describing the behavior of a system of rock blocks and joints. Several basic problems of jointed rock are studied. These examples demonstrate the marked influence joints may have on the stress distribution, displacements, and failure pattern of an underground opening or other structures in jointed rock. A new classification of joints is introduced, based on the application of the joint element to finite element analysis of structures in jointed rock. Normal stiffness, tangential stiffness, and shear strength are used as parameters in the classification system. The methods discussed in this paper allow a jointed rock mass to be treated as a system of blocks and links. Just as analysis of a reinforced concrete building requires detailed knowledge of the behavior of concrete alone and steel alone, the joint stiffness approach calls for and uses detailed description of the behavior of rock blocks and rock joints independently.

On the Theory of Dislocations

Abstract: If, in a multiply‐connected elastic solid, discontinuities are permitted across a stationary barrier in either the strain or its first derivatives or both, dislocations of a more general type than encountered in classical theory are possible. A number of these more general dislocations have been obtained for states of plane and anti‐plane strain in a hollow right circular cylinder when the surface of discontinuity is a single stationary plane barrier. Some of the dislocations found possess the characteristic that although the strain is continuous across the barrier the displacement discontinuity is not one which would be possible in a rigid body. Examination of the conditions for the uniqueness of solution of the boundary value problems of elasticity reveals that when dislocations of the more general type are admitted appropriate data must be given at each point on the specified barrier in addition to the usual information.