Mechanical response of sediments to bubble growth

Johnson, Bruce D.; Boudreau, Bernard P.; Gardiner, Bruce S.; Maass, Regine L.

doi:10.1016/s0025-3227(02)00383-3

Cited by 142 publications

(219 citation statements)

References 14 publications

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“…Muddy marine sediments are elastic solids in which bubbles grow [3] and worms extend burrows by fracture [5]. The burrow around the polychaete, Nereis virens, is a tongue-depressor-shaped crack that extends laterally away from the worm and compresses the worm dorsoventrally (Fig.…”

Section: Burrowing In Mudmentioning

confidence: 99%

“…Calculation of these work components assumes that sediment behaves linear elastically. On time scales of crack extension by fracture, this assumption provides a good approximation of reality [3], but the presence of permanent burrow structures in sediments indicates that this assumption is less accurate over the longer time periods that worms maintain body shape in sediments. The work against the elastic restoring force is calculated as the elastic stored energy, assuming none of that energy is utilized by the burrower to conserve energy.…”

Section: Burrowing In Mudmentioning

confidence: 99%

“…Whereas the mechanics of muddy sediments are dominated by adhesive and cohesive forces binding the mucopolymeric matrix of organic material in which grains are suspended [3], sands comprise much larger grains that rest on each other under gravitational forces and transmit stresses at contact points [51]. Sands have lower organic content than muds, and when submerged their interstitial spaces contain water rather than the aqueous gels in finer sediments [52].…”

Section: Burrowing In Sandmentioning

confidence: 99%

“…Perhaps more importantly, the mechanical responses of muds and sands to forces are less well understood than those of fluids, which are governed by the Navier-Stokes equations [2]. Recent advances in understanding of the mechanics of muds [3] and sands [4] and their application to burrowing [5,6] suggest that not only are the mechanics of crawling and burrowing very different, but mechanisms of burrowing in sands and muds reflect the differences in mechanical properties of the two media [7].…”

Section: Introductionmentioning

confidence: 99%

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Environmental Constraints on the Mechanics of Crawling and Burrowing Using Hydrostatic Skeletons

Dorgan

2010

Exp Mech

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Mechanics, kinematics, and energetics of crawling and burrowing by limbless organisms using hydrostatic skeletons depend on the medium and mode in which the organism is moving. Whether the animal is moving over or through a solid has long been considered important enough to distinguish crawling and burrowing as different terms, and in fact the mechanics are very different. Crawlers use mechanisms to increase friction to generate thrust while reducing resistive friction. Burrowers in elastic muds extend their burrows by fracture, whereas sands are fluidized by burrowers much larger than grain sizes and smaller burrowers displace individual grains. Gravitational forces depend on how closely the density of the organism matches that of its fluid surroundings, therefore frictional forces depend on whether the organism is moving through air or water and fluidization on whether sands are saturated or unsaturated.

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Section: Burrowing In Mudmentioning

confidence: 99%

Section: Burrowing In Mudmentioning

confidence: 99%

Section: Burrowing In Sandmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Environmental Constraints on the Mechanics of Crawling and Burrowing Using Hydrostatic Skeletons

Dorgan

2010

Exp Mech

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“…If the partial pressure of all dissolved gases in the porewater exceeds the ambient pressure and the surface tension of water, free gas is formed. Due to ongoing production of CH 4 , bubbles within the sediments grow and form fractures or disc-shaped cavities (Boudreau et al, 2005;Johnson et al, 2002).…”

Section: Introductionmentioning

confidence: 99%

Pumping methane out of aquatic sediments – ebullition forcing mechanisms in an impounded river

2014

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Abstract. Freshwater systems contribute significantly to the global atmospheric methane budget. A large fraction of the methane emitted from freshwaters is transported via ebullition. However, due to its strong variability in space and time, accurate measurements of ebullition rates are difficult; hence, the uncertainty regarding its contribution to global budgets is large. Here, we analyze measurements made by continuously recording automated bubble traps in an impounded river in central Europe and investigate the mechanisms affecting the temporal dynamics of bubble release from cohesive sediments. Our results show that the main triggers of bubble release were pressure changes, originating from the passage of ship lock-induced surges and ship passages. The response to physical forcing was also affected by previous outgassing. Ebullition rates varied strongly over all relevant timescales from minutes to days; therefore, representative ebullition estimates could only be inferred with continuous sampling over long periods. Since ebullition was found to be episodic, short-term measurement periods of a few hours or days will likely underestimate ebullition rates. Our results thus indicate that flux estimates could be grossly underestimated (by up to~50%) if the correct temporal resolution is not used during data collection.

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Crack extension induced by dissociation of fracture-hosted methane gas hydrate

Jin

Johnson

Cook

2015

Geophys. Res. Lett.

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We investigate extension of a vertical crack filled by water and methane gas induced by dissociation of methane hydrate in low‐permeability muddy sediment. We model the sediment as an impermeable elastic medium and consider a thin sheet configuration of hydrate that initially occupies a vertical fracture. The crack development and the amount of dissociated hydrate are determined using sediment elasticity, fracture mechanics, kinetics of hydrate dissociation, and the equation of state for methane gas. Young's modulus and fracture toughness of the sediment greatly affect the mass of hydrate required for crack extension; lower Young's modulus and higher fracture toughness require greater hydrate mass to induce unstable, buoyancy‐driven crack propagation. Our numerical results suggest that propagation of gas/water‐filled cracks occurs quickly in a matter of seconds and may be an important mechanism for methane transport in low‐permeability sediments when hydrate‐filled fractures are under conditions of gas hydrate dissociation.

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Mechanical response of sediments to bubble growth

Cited by 142 publications

References 14 publications

Environmental Constraints on the Mechanics of Crawling and Burrowing Using Hydrostatic Skeletons

Environmental Constraints on the Mechanics of Crawling and Burrowing Using Hydrostatic Skeletons

Pumping methane out of aquatic sediments – ebullition forcing mechanisms in an impounded river

Crack extension induced by dissociation of fracture-hosted methane gas hydrate

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