Thermomechanical stress–strain numerical modelling of deglaciation since the Last Glacial Maximum in the Adamello Group (Rhaetian Alps, Italy)

Baroni, Carlo; Martino, Salvatore; Salvatore, María Cristina; Mugnozza, Gabriele Scarascia; Schilirò, Luca

doi:10.1016/j.geomorph.2014.08.013

Cited by 27 publications

(16 citation statements)

References 75 publications

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“…Sedimentological and paleobotanical studies of lake and bog sediments show that not only the main valleys but also the tributary valleys were ice-free at the beginning of the Bølling or just before. This is confirmed by radiocarbon dates that calibrate to between 15.9 and 14.3 ka cal BP from sites all across the Alps (Maisch, 1987;van Husen, 1997;Keller and Krayss, 2010;Ivy-Ochs et al, 2006;Kelly et al, 2006;Baroni et al, 2014;Heiri et al, 2014).…”

Section: The Alpine Lateglacialmentioning

confidence: 57%

“…Based on a compilation of radiocarbon dates, Scapozza et al (2015) estimate that the Ticino and Adda glacers reached their LGM furthest extent between 28.5 and 22.9 ka cal BP. At Lake Iseo, ice-free conditions after downwasting of the Oglio glacier ensued no later than 18.6 to 17.9 ka cal BP (Ravazzi et al, 2012;Baroni et al, 2014). Ravazzi et al (2014) suggest LGM Sarca glacier collapse in the Garda Lake region was underway by 17.7 and 17.2 ka cal BP.…”

Section: The Moraine Indicated By the Upper Red Arrow Is At 950 M Amentioning

confidence: 99%

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Glacier variations in the European Alps at the end of the last glaciation

Ivy‐Ochs¹

2015

CIG

163

118

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Section: The Alpine Lateglacialmentioning

confidence: 57%

Section: The Moraine Indicated By the Upper Red Arrow Is At 950 M Amentioning

confidence: 99%

Glacier variations in the European Alps at the end of the last glaciation

Ivy‐Ochs¹

2015

CIG

163

118

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“…We demonstrated that glacial cycles strongly affect the amount of critically stressed joints within an alpine valley (Figures f and h) and each phase of glacier retreat places adjacent rock slopes into a more critically stressed condition (Figure c). Other environmental processes can act on the critically stressed slopes contributing to additional damage and promoting time‐dependent failure, e.g., chemical weathering within joints [ Jaboyedoff et al , ], stress corrosion at fracture tips [ Faillettaz et al , ], ice segregation [ Wegmann et al , ; Hales and Roering , ; Sanders et al , ; Krautblatter et al , ], changes in joint water pressure [ Hansmann et al , ; Preisig et al , ], thermal stresses [ Wegmann and Gudmundsson , ; Gischig et al , ; Baroni et al , ], or seismic fatigue [ Gischig et al , ]. Each of these processes can contribute to further rock slope damage, especially at times when ice loading conditions increase the criticality of the slope.…”

Section: Implications For Paraglacial Rock Slope Instabilitiesmentioning

confidence: 99%

Beyond debuttressing: Mechanics of paraglacial rock slope damage during repeat glacial cycles

et al. 2017

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Cycles of glaciation impose mechanical stresses on underlying bedrock as glaciers advance, erode, and retreat. Fracture initiation and propagation constitute rock mass damage and act as preparatory factors for slope failures; however, the mechanics of paraglacial rock slope damage remain poorly characterized. Using conceptual numerical models closely based on the Aletsch Glacier region of Switzerland, we explore how in situ stress changes associated with fluctuating ice thickness can drive progressive rock mass failure preparing future slope instabilities. Our simulations reveal that glacial cycles as purely mechanical loading and unloading phenomena produce relatively limited new damage. However, ice fluctuations can increase the criticality of fractures in adjacent slopes, which may in turn increase the efficacy of fatigue processes. Bedrock erosion during glaciation promotes significant new damage during first deglaciation. An already weakened rock slope is more susceptible to damage from glacier loading and unloading and may fail completely. We find that damage kinematics are controlled by discontinuity geometry and the relative position of the glacier; ice advance and retreat both generate damage. We correlate model results with mapped landslides around the Great Aletsch Glacier. Our result that most damage occurs during first deglaciation agrees with the relative age of the majority of identified landslides. The kinematics and dimensions of a slope failure produced in our models are also in good agreement with characteristics of instabilities observed in the field. Our results extend simplified assumptions of glacial debuttressing, demonstrating in detail how cycles of ice loading, erosion, and unloading drive paraglacial rock slope damage.

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“…However, damage created by thermoelastic strain in rock masses is frequently dismissed and has only recently been investigated in more detail (Bakun-Mazor et al, 2013;Collins & Stock, 2016;Eppes et al, 2016;Gischig et al, 2011aGischig et al, , 2011bGunzburger et al, 2005;Hall, 1999;Hall & André, 2001;Watson et al, 2004). Baroni et al (2014) highlighted the importance of considering long-term TM effects during deglaciation of an alpine valley, although the resulting displacement rates from their numerical simulations were too low to explain the development of slope instabilities. Gischig et al (2011a) demonstrated how seasonal temperature changes can drive deep rock slope deformation and damage and highlighted an initial~5-year thermaltransient phase of considerable TM damage as the rock mass first adapts to new thermal boundary conditions.…”

Section: Introductionmentioning

confidence: 99%

Thermomechanical Stresses Drive Damage of Alpine Valley Rock Walls During Repeat Glacial Cycles

et al. 2018

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Cycles of glaciation alter the temperature field in proximal alpine valley flanks, driving rock slope damage through thermomechanical stresses. Here we extend simplified assumptions of glacial debuttressing to quantitatively examine how paraglacial bedrock temperature changes, acting in concert with changing ice loads during Late Pleistocene and Holocene glacial cycles, create damage in adjacent rock slopes and prepare future slope instabilities. When in contact with temperate glacier ice, valley walls maintain near isothermal ~0 °C surface temperatures and are shielded from daily and annual cycles. With retreat, rock walls are rapidly exposed to strongly varying temperature boundary conditions, a transition we term “paraglacial thermal shock.” Using detailed, conceptual numerical models based on the Aletsch Glacier in Switzerland, we show that including thermomechanical stresses during simulated glacial cycles creates significantly more rock slope damage than predicted for purely mechanical ice loading and unloading. Glacier advances are especially effective in generating damage as rapid cooling drives contraction of the rock mass reducing joint normal stresses. First time exposure to annual temperature cycles during deglaciation induces a shallow damage front that follows the retreating ice margin, generating damage in a complementary process at shorter time scales. Acting on a reduced strength rock mass, modeled thermomechanical cycles enhance the development of a slope instability with similar attributes as observed in our study area. Our results demonstrate that thermomechanical stresses acting in conjunction with changing ice loads are capable of generating considerable rock slope damage with spatial and temporal patterns controlled by glacier extents.

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Thermomechanical stress–strain numerical modelling of deglaciation since the Last Glacial Maximum in the Adamello Group (Rhaetian Alps, Italy)

Cited by 27 publications

References 75 publications

Glacier variations in the European Alps at the end of the last glaciation

Glacier variations in the European Alps at the end of the last glaciation

Beyond debuttressing: Mechanics of paraglacial rock slope damage during repeat glacial cycles

Thermomechanical Stresses Drive Damage of Alpine Valley Rock Walls During Repeat Glacial Cycles

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