We studied the elastic moduli, ductile creep behavior, and brittle strength of shale-gas reservoir rocks from Barnett, Haynesville, Eagle Ford, and Fort St. John shale in a series of triaxial laboratory experiments. We found a strong correlation between the shale compositions, in particular, the volume of clay plus kerogen and intact rock strength, frictional strength, and viscoplastic creep. V...

Recent studies of excessive multidecade deflections of prestressed segmentally erected box girders revealed that more accurate predictions of the prestress loss due to steel relaxation are needed for the design of large-span creep-sensitive structures. In particular, the loss needs to be calculated as part of creep structural analysis, during which the strain of concrete to which the prestressi...

ABSTRACT. This work is focused on the numerical implementation of thermo-viscoplastic constitutive equations in small and finite strain contexts using FEM. A length scale parameter is introduced implicitly through viscosity in order to address strain localization in the (initial) boundary value problems. The mathematical structure of the infinitesimal viscoplasticity theory is concise and simil...

Cam-Clay nonassociative plasticity exhibits both hardening and softening behaviour, depending on the loading. For many initial data the classical formulation of the quasistatic evolution problem has no smooth solution. We propose here a notion of generalized solution, based on a viscoplastic approximation. To study the limit of the viscoplastic evolutions we rescale time, in such a way that the...

This paper deals with unified elastoplastic and elastic-viscoplastic constitutive equations for metals submitted to large deformations. We present here a newly developed time integration algorithm which is an extension to the viscoplastic range of the classical radial return algorithm for plasticity. The resulting implicit algorithm is both efficient and very inexpensive. This algorithm is also...

We study a numerical method for the simulation of free surface flows of viscoplastic (Herschel-Bulkley) fluids. The approach is based on the level set method for capturing the free surface evolution and on locally refined and dynamically adapted octree cartesian staggered grids for the discretization of fluid and level set equations. We consider an extension of the stable approximation of the N...

A thin-shell program for modeling neotectonics of regional or global lithosphere with faults. Influence of fore-arc structure on the extent of great subduction zone earthquakes. 1994: Effects of multiple phase transitions in a three-dimensional spherical model of convection in Earth's mantle. 2000: Role of temperaturedependent viscosity and surface plates in spherical shell models of mantle con...