Overpressure

About: Overpressure is a research topic. Over the lifetime, 3236 publications have been published within this topic receiving 34648 citations.

Coupled fluid flow and sediment deformation in margin-scale salt-tectonic systems: 1. Development and application of simple, single-lithology models

Abstract: [1] A methodology is presented to model coupled fluid flow and deformation in rifted continental margin composite salt and siliciclastic tectonic systems; and we investigate their compaction and overpressuring behavior associated with continental margin-scale gravitational spreading. Compaction-driven Darcy fluid flow in clastic sediments is coupled through the effective pressure to their frictional-plastic yielding and mechanical deformation. Viscous flow of underlying salt is independent of fluid pressure. Numerical models are adapted to the Oligo-Miocene phase of large-scale gravitational failure in the northwestern Gulf of Mexico, and represent the first study of this system that includes dynamically evolving fluid pressure. Here we present the methodology and prototype models with single uniform sediment lithologies and simple parameterizations of their properties. The models serve to illustrate the interactions among compaction, generation of fluid overpressure, and gravitational failure and spreading. Mechanical and viscous compaction behavior of sandstone-type and shale-type sediments are investigated. Results demonstrate that mechanical compaction can generate moderate overpressure in thick shale-type material, whereas high overpressure requires viscous compaction. In sandstone-type material, only viscous compaction can generate significant overpressure, though this requires tens of millions of years. Changes in the stress regime during gravitational-driven deformation enhance compaction and overpressure. Although illustrative of the methodology and basic processes, none of the prototype single-lithology models satisfactorily reproduces Oligo-Miocene fluid pressure and deformational regimes of the Gulf of Mexico. Numerical models of layered sediments together with an improved formulation of viscous compaction, presented in part 2 of this set of companion papers, are more successful.

Impulsive loading on a concrete structure

Abstract: The current paper deals with the experimental determination of relationships of simultaneous ground shock and airblast parameters against impulsive loading The empirical relationships of peak air pressure, peak reflected airblast pressure along the height of the structure, peak ground acceleration, arriving shock of ground shock, duration of ground shock and the time lag between ground shock and airblast pressure reaching the concrete structure and so forth on a reinforced cement concrete containment scaled model owing to a surface explosion at a certain distance have been established Equations have been developed and utilised in software for a structural response analysis of a reactor containment subjected to surface explosions The generation and the effects of blast wave on the shell structure in the plastic range are discussed Critical distances have been determined for different amounts of blast charges for a typical shell structure The developed methodology of analysis may be adopted in order to

Control method for an overpressure valve in a common-rail fuel supply system

Abstract: Control method for an overpressure valve in a common-rail fuel supply system, the method including the phases of: delivering fuel under pressure, via a high-pressure pump, to a common rail equipped with the overpressure valve that is set to discharge the fuel present in the common rail into a discharge line when the fuel pressure inside the common rail exceeds a safety value; piloting, during a diagnostic test, the high-pressure pump to increase the fuel pressure inside the common rail beyond the safety value in order to trigger operation of the overpressure valve; determining, during the diagnostic test, the flow of the high-pressure pump and/or the fuel pressure inside the common rail; and comparing the flow of the high-pressure pump and/or the fuel pressure inside the common rail during the diagnostic test with respective threshold values.