Electrohydraulic shock wave generation as a means to increase intrinsic permeability of mortar

Maurel, Olivier; Reess, Thierry; Matallah, Mohammed; Ferron, A. De; Chen, W.; Borderie, Christian La; Pijaudier‐Cabot, Gilles; Jacques, Antoine; Rey-Bethbeder, Franck

doi:10.1016/j.cemconres.2010.07.005

Cited by 77 publications

(35 citation statements)

References 13 publications

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“…Although a practically most intriguing application of dynamic comminution modeling may be the fracturing of gas or oil shale by electro-hydraulic pulsed arc (15,16) or by chemical explosion in the pipe of a horizontal borehole, no data on this recently discussed alternative technology exist in the public domain. Nevertheless, a confirmation of the present comminution model can be obtained by fitting the data on the measured exit velocity, v e , of projectiles penetrating concrete walls of different thicknesses.…”

Section: Some Results and Discussionmentioning

confidence: 99%

Comminution of solids caused by kinetic energy of high shear strain rate, with implications for impact, shock, and shale fracturing

Bažant

Caner

2013

Proc. Natl. Acad. Sci. U.S.A.

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Although there exists a vast literature on the dynamic comminution or fragmentation of rocks, concrete, metals, and ceramics, none of the known models suffices for macroscopic dynamic finite element analysis. This paper outlines the basic idea of the macroscopic model. Unlike static fracture, in which the driving force is the release of strain energy, here the essential idea is that the driving force of comminution under high-rate compression is the release of the local kinetic energy of shear strain rate. The density of this energy at strain rates >1,000/s is found to exceed the maximum possible strain energy density by orders of magnitude, making the strain energy irrelevant. It is shown that particle size is proportional to the −2/3 power of the shear strain rate and the 2/3 power of the interface fracture energy or interface shear stress, and that the comminution process is macroscopically equivalent to an apparent shear viscosity that is proportional (at constant interface stress) to the −1/3 power of this rate. A dimensionless indicator of the comminution intensity is formulated. The theory was inspired by noting that the local kinetic energy of shear strain rate plays a role analogous to the local kinetic energy of eddies in turbulent flow.fracture mechanics | dynamic fracture | shale gas | dimensional analysis T he previous studies of high-rate dynamic fracture of rocks, concretes, ceramics, composites, and metals have dealt mainly with the nucleation, propagation, and branching of dynamically propagating cracks, their interference with elastic or shock waves, and the mechanism of development of the zones of densely distributed fractures, called the Mescall zones (1-7). However, a comminution model in the form of a macroscopic constitutive equation that could be used in large dynamic finite element programs for global response of structures is apparently still unavailable.Seeking such a constitutive model, we begin with the analysis of a simple idealized process in which the solid is comminuted to identical particles (Fig. 1). Among simple space-filling regular subdivisions in the plane of maximum shear, regular hexagons are the most likely because they give the smallest surface-to-volume ratio (Fig. 1A) and thus require the minimum energy to form. In the direction normal to the hexagons, we assume the particles to be prismatic.Consider that, at a certain moment, the strain rate (shown in Fig. 1B as a displacement regarded as infinitesimal) becomes high enough for the kinetic energy of shear strain rate to suffice for creating the fractures and interface slips that separate the particles of as yet unknown size. As that happens, the particles release their local kinetic energy, slip against each other, and regain their original undeformed shape, while the particle centers conform to the same macroscopic velocity field (Fig. 1C).For the sake of simplicity and clarity, we will first outline a 2D analysis of comminution in the plane of maximum shear strain rate denoted as _ e D , and leave the 3D generaliza...

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Section: Some Results and Discussionmentioning

confidence: 99%

Comminution of solids caused by kinetic energy of high shear strain rate, with implications for impact, shock, and shale fracturing

Bažant

Caner

2013

Proc. Natl. Acad. Sci. U.S.A.

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“…where k and α in the empirical formula (1) are parameters related to the experimental environment and electrode geometry [44,45]. ese two parameters represent the energy conversion characteristics of the WSW in different experimental conditions [42].…”

Section: Data Fitting and Contrastmentioning

confidence: 99%

Experimental Study of Pulsed Discharge Underwater Shock-Related Properties in Pressurized Liquid Water

Bian

Dong

Zhao

et al. 2018

Advances in Materials Science and Engineering

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Engineering background of hydraulic fracturing is applied to improve the permeability of unconventional gas wells, such as coal seams and shale gas wells, by a pulsed discharge mechanism. We studied the general relations between water shock wave properties (the maximum pressure, wave velocity, and energy conversion efficiency), the discharge voltage, and hydrostatic pressure during high-voltage pulsed discharge experiments in pressurized liquid water. e following observations were made: (1) when the discharge voltage increased from 7 kV to 13 kV, the maximum pressure increased from 12.6 MPa (hydrostatic pressure P H � 12 MPa) to 40 MPa (P H � 6 MPa), wave velocity increased from 1418 m/s (P H � 12 MPa) to 1454 m/s (P H � 6 MPa), and energy conversion efficiency increased from 9% to 11%, and (2) when hydrostatic pressure increased from 0 MPa to 12 MPa, the maximum pressure and wave velocity augmented and then diminished slowly (the critical hydrostatic pressure occurs in the 3 to 6 MPa range), whereas the change of energy conversion efficiency was not obvious. eir properties are explained by the variation of electrical parameters during the pulsed discharge.

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“…Dynamic comminution (i.e., fragmentation, crushing and pulverization), due to high shear strain rate occurs in many situations and processes, ranging from projectile or meteorite impact on rocks, concrete, composites, metals and ceramics (Deshpande and Evans 2008;Doyoyo 2002;Ferri et al 2010;Mescall and Weiss 1984;Wei et al 2009), to fracturing of gas or oil shale by chemical explosions or electro-hydraulic pulsed arc in the horizontal borehole (Hemmert et al 2010;Maurel et al 2010). There exists a vast literature on the subject Cadoni et al 2001;Camacho and Ortiz 1996;Deshpande and Evans 2008;Doyoyo 2002;Ferri et al 2010;Forquin et al 2008;Frank et al 2012;Gailly and Espinosa 2002;Gatuingt and Pijaudier-Cabot 2002;Grady 1982;Grady 1998;Grady and Kipp 1979;Grady and Kipp 1995;Grady 1990;Kožar and Ožbolt 2010;Mescall and Weiss 1984;Mott 1947;Ožbolt et al 2011;Shih et al 1998;Wei et al 2009) and many aspects are well understood, including the micro-mechanics of dynamic propagation and branching of individual cracks (Freund 1990).…”

Section: Introductionmentioning

confidence: 99%

Viscous energy dissipation of kinetic energy of particles comminuted by high-rate shearing in projectile penetration, with potential ramification to gas shale

Bažant

Zhao

et al. 2015

Int J Fract

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While dynamic comminution is of interest to many processes and situations, this work is focused on the projectile impact onto concrete walls, in which predictions have been hampered by the problem of the so-called 'dynamic overstress'. Recently, in analogy with turbulence, Bažant and Caner modeled the overstress as an additional viscous stress generated by apparent viscosity that accounts for the energy dissipation due to kinetic comminution of concrete into small particles at very high shear strain rate. Their viscosity estimation, however, was approximate since it did not satisfy the energy balance exactly. Here their model is extended and refined by ensuring that the drop of local kinetic energy of high shear strain rate of form- ing particles must be exactly equal to the energy dissipated by interface fracture of these particles. The basic hypothesis is that the interface fracture occurs instantly, as soon as the energy balance is satisfied. Like in the preceding work, this additional apparent viscosity is a power function of the rate of the deviatoric strain invariant. But here the power exponent is different, equal to −7/3, and the apparent viscosity is found to be proportional also to the time derivative of the rate of that invariant, i.e., to the second derivative of the shear strain. It is assumed that the interface fracture that comminutes the material into small particles occurs instantly, as soon as the local kinetic energy of shear strain rate in the forming particles becomes equal to the energy required to form interface fractures. The post-comminution behavior, including subsequent further comminution and clustering into bigger particle groups to release the kinetic energy that is being dissipated by inter-group friction, is discussed and modeled. The present formulation makes it possible to eliminate the artificial damping of all types, which is normally embedded in commercial finite element codes but is not predictive since it is not justified physically. With the aforementioned improvements, and after implementation into the new microplane model M7 for fracturing damage in concrete (which includes the quasi-static rate effects), the finite element predictions give superior agreement with the measured exit velocities of steel projectiles penetrating concrete walls of different thicknesses and with the measured depths of penetration into concrete blocks by projectiles of different veloci-123 78 Y. Su et al. ties. Finally it is pointed out that the theory presented may also be used to predict proximate fragmentation and permeability enhancement of gas shale by powerful electric pulsed-arc explosions in the borehole.

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Electrohydraulic shock wave generation as a means to increase intrinsic permeability of mortar

Cited by 77 publications

References 13 publications

Comminution of solids caused by kinetic energy of high shear strain rate, with implications for impact, shock, and shale fracturing

Comminution of solids caused by kinetic energy of high shear strain rate, with implications for impact, shock, and shale fracturing

Experimental Study of Pulsed Discharge Underwater Shock-Related Properties in Pressurized Liquid Water

Viscous energy dissipation of kinetic energy of particles comminuted by high-rate shearing in projectile penetration, with potential ramification to gas shale

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