The effect of suction on the hydro-mechanical behaviour of chalk rocks

Taïbi, Saïd; Duperret, Anne; Fleureau, Jean‐Marie

doi:10.1016/j.enggeo.2009.02.012

Cited by 51 publications

(24 citation statements)

References 25 publications

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“…In reservoir and mining engineering, the matrix suction has been identified as significantly affecting the behavior of geoformations (Schmitt et al 1994;Ramos Da Silva et al 2008;Van Eeckhout 1976). Laboratory tests conducted on chalks have demonstrated that the mechanical strength of rocks is reduced under high-moisture conditions (Taibi et al 2009;Schroeder et al 1998). Other experimental results also show that there is a strong correlation between relative fluid saturation and mechanical behavior such as pore collapse, yielding, plasticity, and failure (Bell et al 1990;Talesnick et al 2001;Duperret et al 2005;Brignoli and Sartori 1993;Papamichos et al 1997;Jia et al 2010).…”

Section: Introductionmentioning

confidence: 97%

“…Several constitutive models have been developed for partially saturated rocks in the last two decades (Brignoli et al 1994;Piau and Maury 1995;Maury et al 1996;Papamichos et al 1997;Homand and Shao 2000;Collin et al 2002;Taibi et al 2009;Navarro et al 2010). However, quite a few problems exist in these models; For example, the models proposed by Brignoli et al (1994) and Papamichos et al (1997) take water saturation in the strength parameter, but ignore suction, the effect of which is essential in constitutive models (Schmitt et al 1994;Ramos Da Silva et al 2008;Van Eeckhout 1976).…”

Section: Introductionmentioning

confidence: 99%

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An Elastoplastic Model for Partially Saturated Collapsible Rocks

2015

Rock Mech Rock Eng

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A unified elastoplastic model for describing the stress-strain behavior of partially saturated collapsible rocks is proposed. The elastic-plastic response due to loading and unloading is captured using bounding surface plasticity. The coupling effect of hydraulic and mechanical responses is addressed by applying the effective stress concept. Special attention is paid to the rock-fluid characteristic curve (RFCC), effective stress parameter, and suction hardening. A wide range of saturation degree is considered. The characteristics of mechanical behavior in partially saturated collapsible rocks are captured for all cases considered.

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Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

An Elastoplastic Model for Partially Saturated Collapsible Rocks

2015

Rock Mech Rock Eng

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“…A number of experimental investigations and numerical modeling have been developed on these topics. For example, some studies focused on the influences of water saturation degree and water activity of mechanical responses of various chalks, [3,4,8,10,16,22]. Various constitutive models, respectively based on unsaturated soil mechanics concepts and inter-granular pressure solution process, have been proposed [2,13,15].…”

Section: Introductionmentioning

confidence: 99%

A micromechanical modeling of ductile behavior of a porous chalk: Formulation, identification, and validation

Lin¹,

Xie²,

Shao³

et al. 2011

Num Anal Meth Geomechanics

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SUMMARYPorosity strongly affects the overall ductile behavior of cohesive geomaterials undergoing plastic deformation. In the present paper, we proposed an original micromechanical approach that suitably couples Drucker-Prager-type plasticity, evolving porosity under general triaxial loadings. The resulting model has the advantage to be based on a single macroscopic yield function, which also plays the role of plastic potential. It is shown that this yield function is particularly appropriate to account for the pore collapse and plastic shearing mechanisms that govern the mechanical behavior of the studied Lixhe chalk. Finally, the new model is implemented and validated by comparison to triaxial tests data, covering a wide range of confining pressures.

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“…Shearing tests were conducted under saturated conditions, elastic modulus were thus determined for saturated conditions. Considering the particular chalk lithology, previous studies (Sorgi et De Gennaro, 2007 ;Taibi et al, 2009) have shown that water-saturated chalk samples present a rigidity reduction of 2 compared with dry-chalk samples. Dry-chalk samples E t50 are thus calculated using the measured saturated (sat) chalk samples and used for dry conditions in the numerical models.…”

Section: Coastal Morpho-bathymetrymentioning

confidence: 99%

“…The capillary cohesion for wet sand is estimated using an effective-stress approach based on a simple model for granular soils (Taibi et al, 2009). We consider the water content (1%), the grains sizes (from 200 to 400 μm), the sand bulk density (from 1.5 to 1.8 kg/m 3 ) and the associated void ratio (between 0.35 and 0.91) to estimate the capillary cohesion.…”

Section: Tables Captionmentioning

confidence: 99%

Numerical and physical modelling of coastal cliff retreat processes between La Hève and Antifer capes, Normandy (NW France)

Cossec

Duperret

Vendeville³

et al. 2011

Tectonophysics

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The study area is located along the French eastern Channel coastline, in Upper Normandy, between the La Hève and Antifer capes. The sedimentary series dip North-Eastward by 0.7° and comprise clay layers (Kimmeridgian and Albian clays) located at varying vertical elevation along the cliff (about 90m high). This coastal cliff section is undergoing slow gravitational deformation, assumed to take place along the clay layers. Using numerical and experimental models, we investigated the role of clay layers, acting as potential detachment layers, on the development of gravitational instabilities. In order to properly design our models, we characterized the rock mechanical parameters using triaxial shear tests on in-situ samples dated from Kimmeridgian to Cenomanian. We ran a series of numerical simulations using a finite-element code applied to 2-D cliff cross section having varying lithological and mechanical layering. Under the sole effect of gravity forces, the plastic strains are mainly localised along the two clay layers, and the predicted displacements evidence a seaward sliding of the cliff. We further investigated gravitational deformation in the cliff using experimental models subjected to high pore-fluid pressure using by injecting compressed air at the base of the model. The presence of fluid overpressure can trigger spontaneous dismemberment of a cliff that would otherwise remain stable.The region of the model located near the initial cliff spread seaward, which generated a set of normal -2-faults that propagated landward and create a frontal toe bulge. We modelled a more complex initial geometry closer that observed in the field by simulating the northward progressive deepening of a potential décollement (the Gault clay). In the segment of the model where the potential décollement layer lay above or at the cliff's base, the absence of frontal buttress allowed for a large part of the cliff to slide seaward. The compressional toe of the deformed wedge progressively grew, thus acting as a buttress preventing further sliding. Removal of this toe by erosion lead to renewed gliding. Going northward, the vertical position of the potential décollement layer deepened, below the base of the cliff. There, the chalky shore platform acts as a buttress and the cliff deformation and seaward translation stops. Results lead us to hypothesize that cliff retreat would be faster where the potential décollement layer is located higher in the cliff along the southern segment. Therefore, the overall cliff trend would progressively rotate counterclockwise with ongoing deformation and erosion. This modelling works illustrates why the coastline trend changes drastically between the north (N60E) and the south segment (N25E). This progressive coastline re-orientation through time is confirmed by the fan-shape morphology of the bathymetry offshore the southern segment whereas the northern one presents a slight and regular slope.

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The effect of suction on the hydro-mechanical behaviour of chalk rocks

Cited by 51 publications

References 25 publications

An Elastoplastic Model for Partially Saturated Collapsible Rocks

An Elastoplastic Model for Partially Saturated Collapsible Rocks

A micromechanical modeling of ductile behavior of a porous chalk: Formulation, identification, and validation

Numerical and physical modelling of coastal cliff retreat processes between La Hève and Antifer capes, Normandy (NW France)

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