Embedment

About: Embedment is a research topic. Over the lifetime, 2441 publications have been published within this topic receiving 31444 citations.

Elastoplastic consolidation solutions for scaling from shallow penetrometers to pipelines

Abstract: The build-up of friction on seabed pipelines is an important design consideration, affecting their stability and the resulting in-service strain and fatigue. The consolidation beneath a partially embedded pipeline has been investigated in the past and linked to the build-up of axial pipe–soil resistance. This paper extends previous work by providing solutions for consolidation around a new class of shallow penetrometer, to provide a basis to scale from site investigation results directly to the build-up of pipeline friction. Small-strain finite element analyses, using the Modified Cam Clay soil model, are presented for the novel toroid and ball penetrometers. The effects of initial penetrometer embedment, device roughness, strength gradient, and overload ratio have been explored in a comprehensive manner, and are compared with pipe results. The toroid penetrometer shows excellent agreement with an element of an infinitely long pipe, simplifying the scaling process. The ball penetrometer shows a faster con...

Hydronic heating system

Abstract: A hydronic heating system that includes a tube or series of tubes placed on modular composite panels. The panels are fabricated with a grooved surface to permit the flush embedment of the tubes on the panels.

Mechanical Performance of Curved FRP Rebars: Part I - Experimental Study

Abstract: This paper summarised an experimental programme undertaken at the University of Sheffield to examine the performance of curved FRP composites as structural reinforcing materials. Direct pullout tests were conducted on thermoplastic composite strips embedded in concrete cubes. A total of 47 specimens and 19 different configurations were tested. The parameters that were investigated included geometry of the bend, surface treatment, embedment length and concrete strength. Results on the pullout tests on curved FRP composites indicated that the capacity of the composite could be as low as 25% of the ultimate tensile strength of the material parallel to the fibres. Based on the test results, it is recommended that the bending radius of 4 times the bar thickness could be used to guarantee the strength of composite to 40% of the strength parallel to the fibres.

A multi-asperity plastic-contact crack plane model for geomaterials

Abstract: SUMMARY A mechanistic constitutive model for fully formed cracks in geomaterials, such as concrete and rock, is presented. A three-dimensional characterisation of the crack morphology is employed in which the crack surface is idealised as a series of conical teeth and corresponding recesses of variable height and slope. Based on this geometrical characterisation, an effective contact function is derived to relate the contact stresses that develop on the sides of the teeth to the net stresses on a crack plane. Plastic embedment and frictional sliding are simulated using a local plasticity model in which the plastic surfaces are expressed in terms of the contact surface function in cylindrical relative displacement space. Finally, the performance of the model is assessed against several sets of experimental data from direct shear tests, and it is concluded that the model is able to capture key characteristics of the behaviour of fully formed cracks in geomaterials. Copyright © 2012 John Wiley & Sons, Ltd.

Limits of Acid Fracture Conductivity Correlation Improvement Through Acid Fracture Surface Characterization

Abstract: The classical theoretical framework of fracture conductivity for rough acid-etched surfaces is the Nierode and Kruk correlation, given by an exponential equation of two parts: the conductivity under zero-closure stress and the rate of conductivity change with closure stress. The first part has been related to fracture width and the second one, to rock embedment strength. This study, based on experiments that used samples from whole cores of an oil producer limestone, analyzed the fitness of laboratory-measured conductivities to the exponential conductivity correlation model. By means of a comprehensive 3D acid-etched surface characterization, this study showed that the use of surface parameters, measured at zero closure stress, can improve only the first part of the exponential correlation. The rate of conductivity change with closure stress is determined by the fracture width reduction under closure stress, while the effects of asperities in contact and related tortuosity are negligible. This conclusion is based on a physical hypothesis, on correlations of the surface parameters with the mentioned parts or coefficients, and on the relation between contact area ratio and fracture width. The best acid-fracture conductivity correlation developed has its first part based on a surface characterization parameter and the second one based on the rock embedment strength. This correlation showed superior accuracy compared with the Nierode and Kruk correlation and represents the maximum possible improvement through surface parameters use for the studied limestone. There is still significant room for improvement in the rate of conductivity change with closure stress. This requires a new model of fracture deformation under closure stress or, at least, a new rock mechanic parameter to replace rock embedment strength. Introduction The success of acid-fracturing stimulation relies on fracture conductivity and effective fracture length, which depends on acid transport along the fracture, acid leakoff, and acid reaction at the fracture faces. This study focuses on fracture conductivity. The first and still mostly used acid fracture conductivity correlation is the Nierode and Kruk (1973) one. The best fit of their experimental results was obtained with an exponential equation of two parts. The first part, C1, is the initial conductivity, i.e., the conductivity under zero-closure stress. The second part, C2, is the rate of conductivity change with closure stress. C1 has been related to fracture width and C2 to rock embedment strength. Nierode and Kruk correlation does not take into account surface characteristics. A clear drawback of Nierode and Kruk correlation is its prediction of continuous increase of conductivity with acid volume and/or contact time. Broaddus et al. (1968) had pointed out that there should be an optimum