Chemically- and mechanically-mediated influences on the transport and mechanical characteristics of rock fractures
Chemically- and mechanically-mediated influences on the transport and mechanical characteristics of rock fractures
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发表时间：
2008
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通讯作者：
K. Min;J. Rutqvist;D. Elsworth
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作者：
K. Min;J. Rutqvist;D. Elsworth
提出了一个模型来描述由于力学和化学耦合作用而引起的裂隙岩石力学和输运特性的变化。具体的影响是溶解速率的升高对接触颗粒的影响，这导致应力和温度依赖的永久关闭。一个代表这种类似压力溶解行为的模型可以根据接触裂缝的基本热力学性质来定义阈值和由此产生的响应。这些关系被整合到裂缝闭合的应力加强模型中，以定义应力和温度循环过程中孔径损失和行为的应力和温度依赖关系。这些模型与实验室和现场实验结果相比较，均能反映解耦的等压和等温响应。该模型用于探讨这些响应对岩石中加热结构的影响。结果表明，在没有化学作用的情况下，最终诱导应力降低，冷却到环境条件后最终应力永久降低。同样，渗透率可能低于不考虑化学作用的情况，即使在冷却到环境温度后，净降低也很明显。这些迄今为止被忽视的影响可能对岩石中加热结构的性能产生相应的重大影响，例如用于容纳放射性废物的储存库。
A model is presented to represent changes in the mechanical and transport characteristics of fractured rock that result from coupled mechanical and chemical effects. The specific influence is the elevation of dissolution rates on contacting asperities, which results in a stress- and temperature-dependent permanent closure. A model representing this pressure-dissolution-like behavior is adapted to define the threshold and resulting response in terms of fundamental thermodynamic properties of a contacting fracture. These relations are incorporated in a stress-stiffening model of fracture closure to define the stress- and temperature-dependency of aperture loss and behavior during stress and temperature cycling. These models compare well with laboratory and field experiments, representing both decoupled isobaric and isothermal responses. The model was applied to explore the impact of these responses on heated structures in rock. The result showed a reduction in ultimate induced stresses over the case where chemical effects were not incorporated, with permanent reduction in final stresses after cooling to ambient conditions. Similarly, permeabilities may be lower than they were in the case where chemical effects were not considered, with a net reduction apparent even after cooling to ambient temperature. These heretofore-neglected effects may have a correspondingly significant impact on the performance of heated structures in rock, such as repositories for the containment of radioactive wastes.