Control of the geometric arrangement of material heterogeneities on strain localization at the brittle-to-ductile transition in experimentally deformed carbonate rocks
Control of the geometric arrangement of material heterogeneities on strain localization at the brittle-to-ductile transition in experimentally deformed carbonate rocks
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材料异质性几何排列对实验变形碳酸盐岩脆性到韧性转变应变局部化的控制
DOI：
10.1016/j.jsg.2020.104038
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发表时间：
2020
影响因子：
3.1
通讯作者：
Dresen
中科院分区：
文献类型：
--
作者：
Nardini;Rybacki;Krause;Morales;L. F. G;Dresen
三轴高温（900 °C）变形实验在Paterson型变形装置中以恒定应变速率对卡拉拉大理石圆柱体进行，该圆柱体具有两个右或左步进、不重叠的Solnhofen石灰岩弱夹杂物，与圆柱体的纵轴成45°。在不同的约束条件下（30、50、100和300 MPa），我们在大理岩基体中诱发了不同程度的脆性变形，并研究了脆性先驱体对非均匀性诱发的高温剪切带的形成和发展的影响。包裹体的初始排列导致样品跨越区域的超压（收缩）或欠压（伸展）区域。在低限制（30和50 MPa）丰富的脆性变形观察，但微裂缝的空间分布是依赖于跨越区域的运动学：微裂纹发生沿着剪切平面之间的夹杂物（inextensional bridgesamples），或广泛分布的跨越区域外（收缩bridgesamples）。因此，韧性变形局限于沿着夹杂物平面在拉伸桥样品，而不是分布在大面积的矩阵在收缩桥样品。如果微裂纹被抑制（高约束），应变是由粘性蠕变和应变逐步de-localizes inextensional bridgessamples容纳。我们的实验表明，脆性的前体增强的韧性变形制度的本地化程度，但只有当预先存在的不均匀性的相互作用诱导之间的拉伸平均应力制度。
Triaxial high temperature (900 °C) deformation experiments were conducted at constant strain rate in a Paterson-type deformation apparatus on cylinders of Carrara marble with two right or left stepping, non-overlapping weak inclusions of Solnhofen limestone, oriented at 45° to the cylinders’ longitudinal axes. Applying different values of confinement (30, 50, 100 and 300 MPa) we induced various amounts of brittle deformation in the marble matrix and investigated the effect of brittle precursors on the initiation and development of heterogeneity-induced high temperature shear zones.Viscosity contrast between the matrix and the inclusions induces local stress concentration at the tips of these latter. The initial arrangement of the inclusions results in either an overpressured (contractional) or underpressured (extensional) domain in the step-over region of the sample. At low confinement (30 and 50 MPa) abundant brittle deformation is observed, but the spatial distribution of microfractures is dependent on the kinematics of the step-over region: microcracks occur either along the shearing plane between inclusions (inextensional bridgesamples), or broadly distributed outside the step-over region (contractional bridgesamples). Accordingly, ductile deformation localizes along the inclusions plane in theextensional bridgesamples as opposed to distributing over large areas of the matrix in thecontractional bridgesamples. If microcracking is suppressed (high confinement), strain is accommodated by viscous creep and strain progressively de-localizes inextensional bridgesamples. Our experiments demonstrate that brittle precursors enhance the degree of localization in the ductile deformation regime, but only if the interaction of pre-existing heterogeneities induces an extensional mean stress regime in between.
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DOI：
--
发表时间：
2013
期刊：
影响因子：
--
作者：
G. Pennacchioni;Eleonora Zucchi
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DOI：
--
发表时间：
2015
期刊：
影响因子：
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作者：
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通讯作者：
I. Moeck
DOI：
--
发表时间：
1987
期刊：
影响因子：
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作者：
P. Jordan
通讯作者：
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两种粘度的故事
影响因子：
3.1
作者：
M. Jessell;P. Bons;A. Griera;L. Evans;C. Wilson
通讯作者：
C. Wilson
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影响因子：
3.1
作者：
N. Mancktelow;G. Pennacchioni
通讯作者：
G. Pennacchioni