Subcritical Crack Growth and Progressive Failure in Carrara Marble Under Wet and Dry Conditions
Subcritical Crack Growth and Progressive Failure in Carrara Marble Under Wet and Dry Conditions
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DOI：
10.1029/2017jb014956
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发表时间：
2018-05
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影响因子：
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通讯作者：
A. Voigtländer;K. Leith;M. Krautblatter
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文献类型：
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作者：
A. Voigtländer;K. Leith;M. Krautblatter
我们的渐进式岩石边坡破坏的概念是一方面嵌入在聚合亚临界裂纹扩展机制和其他敏感的环境条件，特别是水。为了预测岩石边坡的破坏动力学，揭示水对亚临界裂纹扩展机制和材料性能的影响是一个关键的要求。我们提出了一个示例性的岩石，卡拉拉大理石随时间变化的变形的实验数据。我们对大型卡拉拉大理石样品进行了倒置单边切口弯曲蠕变试验，以模拟具有受控供水的开放式节理系统。在两个步骤中施加恒定应力，接近先前确定的临界基线应力的22-85%。将方解石饱和水引入亚临界应力样品导致应变立即增加高达一个数量级。在所有载荷水平下，在湿和干样本中，缺口尖端的非弹性损伤均随时间累积。如果存在水，亚临界裂纹扩展和局部晶间断裂的演变会增强，并且当负载高于80%时，很容易接近第三次蠕变。瞬时应变响应归因于表面能的降低和水向岩石中的扩散。由此产生的更柔顺和更弱的流变性甚至可以将亚临界应力转变为临界状态。随着时间的推移，亚临界和化学增强机制逐渐改变，特别是晶界，这成为卡拉拉大理石渐进故障的关键控制。
Our concept of progressive rock slope failures is on the one hand embedded in aggregated subcritical crack growth mechanisms and on the other sensitive to environmental conditions, especially water. To anticipate failure dynamics in rock slopes, it is a key requirement to reveal the influence of water on subcritical crack growth mechanisms and material properties. We present experimental data on the time‐dependent deformation of an exemplary rock, Carrara marble. We employed inverted single‐edge notch bending creep tests on large Carrara marble samples to mimic an open joint system with controlled water supply. Constant stress was applied in two steps approaching 22–85% of a previously determined critical baseline stress. Introducing calcite‐saturated water to subcritical stressed samples caused an immediate increase in strain by up to an order of magnitude. Time‐dependent accumulation of inelastic damage at the notch tip occurred in wet and dry samples at all load levels. Subcritical crack growth and the evolution of localized intergranular fractures are enhanced if water is present and readily approach tertiary creep when loaded above 80%. The immediate strain response is attributed to the reduction of surface energy and diffusion of the water into the rock. The resultant more compliant and weaker rheology can even turn the subcritical stress into a critical state. Over time, subcritical and chemically enhanced mechanisms progressively alter especially grain boundaries, which become the key controls of progressive failure in Carrara marble.