In situ tensile fracture toughness of surficial cohesive marine sediments

Johnson, Bruce D.; Barry, Mark A.; Boudreau, Bernard P.; Jumars, Peter A.; Dorgan, Kelly M.

doi:10.1007/s00367-011-0243-1

Cited by 40 publications

(63 citation statements)

References 26 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…12 Tensile fracture toughness, K IC , versus Young's modulus, E, for sediments from the Windsor site. The two parameters are strongly correlated (K IC data extracted from Johnson et al 2012) Variability in Young's modulus, both within and between sites, can be attributed to numerous factors, including grain size and porosity. The effects of consolidation are evident in the profiles as E increases and porosity decreases with depth.…”

Section: Discussionmentioning

confidence: 99%

“…At the Canard site in an area of no more than 10 m 2 , large variability in E was observed both laterally (over distances less than 1 m) and with depth. The highest E values recorded with the mIDMT, 1,000-1,600 kPa, were from the Canard site at depths below 20 cm where sediments are dominantly coarse sand (Johnson et al 2012).…”

Section: Minas Basinmentioning

confidence: 96%

“…Overconsolidated, silty to sandy-silt sediments with varying amounts of clay characterize both sites. The Windsor site displays a homogenous grain size distribution (~23-30 μm mean grain diameter) across the tidal flats (Daborn et al 2003), whereas the Canard site has a larger mean grain size (~40-70 μm) and the surface sediments contain several layers of coarse sand (Johnson et al 2012).…”

Section: Field Sites and Coringmentioning

confidence: 98%

“…The Minas Basin, Nova Scotia, Canada, has two field sites (Windsor and Canard, Fig. 1a) where sediments were used in previous studies of bubble growth and sediment fracture (Barry et al 2010;Johnson et al 2012). Overconsolidated, silty to sandy-silt sediments with varying amounts of clay characterize both sites.…”

Section: Field Sites and Coringmentioning

confidence: 99%

See 3 more Smart Citations

A new instrument for high-resolution in situ assessment of Young’s modulus in shallow cohesive sediments

2012

Self Cite

View full text Add to dashboard Cite

This paper describes a new, miniature, instrumented flat dilatometer (mIDMT) designed to assess variations in nearly continuous compressive stress-strain behaviour with depth in shallow cohesive sediments. The instrument was tested both in situ in the Bay of Fundy, Nova Scotia, Canada, and in cored samples from Willapa Bay, Washington, USA. Comparisons between probe and laboratory uniaxial assessments for other elastic materials-gelatine and foam rubber specifically-show strong agreement over the range of strains induced in the experiments. Observed values of Young's modulus (E) for the gelatine and ethylene-vinyl acetate foam ranged from 6-343 kPa. Sediment stress-strain curves were distinctly linear for the overconsolidated fine-grained sediments of the Minas Basin, and values of E were found to increase with depth from near zero to 500-1,300 kPa at 20 cm depth. At the Willapa site, the sandy tidal flat sediments also behave elastically but E tended to increase more strongly with depth than for sediments from the Minas Basin. Young's modulus was inversely correlated to porosity at all sites tested, and linearly related to shear strength in the Minas Basin. The newly designed instrument has much finer resolution than for other, similar methods of determining E in situ, and it provides data at a resolution sufficient to assess smallscale processes such as gas bubble growth and infaunal locomotion, for which elastic constants are needed for modelling and prediction.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Minas Basinmentioning

confidence: 96%

Section: Field Sites and Coringmentioning

confidence: 98%

Section: Field Sites and Coringmentioning

confidence: 99%

See 2 more Smart Citations

A new instrument for high-resolution in situ assessment of Young’s modulus in shallow cohesive sediments

2012

Self Cite

View full text Add to dashboard Cite

show abstract

“…In natural muds, fracture toughness and stiffness are low in the top approximately 2-3 cm of sediments [24,25], corresponding to the depth distribution of A. brevis [16]. At the surface, fracture toughness approaches zero, indicating that surface muds are non-cohesive, high-porosity aggregates and that linear elastic fracture occurs only below the surface layer.…”

Section: Results and Discussion (A) Armandia Brevis Does Not Extend Bmentioning

confidence: 99%

Meandering worms: mechanics of undulatory burrowing in muds

2013

Self Cite

View full text Add to dashboard Cite

Recent work has shown that muddy sediments are elastic solids through which animals extend burrows by fracture, whereas non-cohesive granular sands fluidize around some burrowers. These different mechanical responses are reflected in the morphologies and behaviours of their respective inhabitants. However, Armandia brevis, a mud-burrowing opheliid polychaete, lacks an expansible anterior consistent with fracturing mud, and instead uses undulatory movements similar to those of sandfish lizards that fluidize desert sands. Here, we show that A. brevis neither fractures nor fluidizes sediments, but instead uses a third mechanism, plastically rearranging sediment grains to create a burrow. The curvature of the undulating body fits meander geometry used to describe rivers, and changes in curvature driven by muscle contraction are similar for swimming and burrowing worms, indicating that the same gait is used in both sediments and water. Large calculated friction forces for undulatory burrowers suggest that sediment mechanics affect undulatory and peristaltic burrowers differently; undulatory burrowing may be more effective for small worms that live in sediments not compacted or cohesive enough to extend burrows by fracture.

show abstract

Natural remanent magnetization acquisition in bioturbated sediment: General theory and implications for relative paleointensity reconstructions

Egli

Zhao

2015

Geochem Geophys Geosyst

View full text Add to dashboard Cite

We present a general theory for the acquisition of natural remanent magnetizations (NRM) in sediment under the influence of (a) magnetic torques, (b) randomizing torques, and (c) torques resulting from interaction forces. Dynamic equilibrium between (a) and (b) in the water column and at the sedimentwater interface generates a detrital remanent magnetization (DRM), while much stronger randomizing torques may be provided by bioturbation inside the mixed layer. These generate a so-called mixed remanent magnetization (MRM), which is stabilized by mechanical interaction forces. During the time required to cross the surface mixed layer, DRM is lost and MRM is acquired at a rate that depends on bioturbation intensity. Both processes are governed by a MRM lock-in function. The final NRM intensity is controlled mainly by a single parameter c that is defined as the product of rotational diffusion and mixed-layer thickness, divided by sedimentation rate. This parameter defines three regimes: (1) slow mixing (c < 0.2) leading to DRM preservation and insignificant MRM acquisition, (2) fast mixing (c > 10) with MRM acquisition and full DRM randomization, and (3) intermediate mixing. Because the acquisition efficiency of DRM is larger than that of MRM, NRM intensity is particularly sensitive to c in case of mixed regimes, generating variable NRM acquisition efficiencies. This model explains (1) lock-in delays that can be matched with empirical reconstructions from paleomagnetic records, (2) the existence of small lock-in depths that lead to DRM preservation, (3) specific NRM acquisition efficiencies of magnetofossil-rich sediments, and (4) some relative paleointensity artifacts.

show abstract

In situ tensile fracture toughness of surficial cohesive marine sediments

Cited by 40 publications

References 26 publications

A new instrument for high-resolution in situ assessment of Young’s modulus in shallow cohesive sediments

A new instrument for high-resolution in situ assessment of Young’s modulus in shallow cohesive sediments

Meandering worms: mechanics of undulatory burrowing in muds

Natural remanent magnetization acquisition in bioturbated sediment: General theory and implications for relative paleointensity reconstructions

Contact Info

Product

Resources

About