Influence of flaws on joint spacing and saturation: Results of one‐dimensional mechanical modeling
Influence of flaws on joint spacing and saturation: Results of one‐dimensional mechanical modeling
复制标题
缺陷对节理间距和饱和度的影响：一维力学建模的结果
DOI：
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发表时间：
2006
期刊：
影响因子：
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通讯作者：
A. Polansky
中科院分区：
文献类型：
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作者：
M. Fischer;A. Polansky
在层状沉积岩或力学各向异性岩石中，节理通常以横向持久的平行组合出现，具有独特的间距属性。其中三个属性包括节理间距的正偏斜分布，中间间距与机械层厚度之间的正相关关系，以及岩石中节理饱和的趋势，以及层厚与中间节理间距的比值接近1。我们确定了总施加应变、力学相互作用、节理传播速度和缺陷是渐进节理过程中的关键变量，并使用力学相互作用节理的一维模型来表征岩石中缺陷的数量、大小和尺寸分布对节理间距的具体影响。对于给定的缺陷尺寸分布，模态缺陷尺寸对间距分布形状、中间间距和饱和度没有影响。缺陷越少的层接近饱和的速度越慢，达到饱和的节理越少，中间节理间距越大。这些层中的节理间距分布具有方差和偏度，可能比缺陷较多的层大1-3个数量级。缺陷尺寸范围影响节理层接近饱和的速率，但不影响饱和状态下的节理数。尽管较窄的缺陷尺寸范围倾向于产生更多的紧密间隔节理，但产生的间距分布是相似的。缺陷尺寸分布的偏度影响层接近饱和的速率，以及在饱和时产生的节理间距分布的形状。负偏斜的缺陷尺寸分布促进了节理间距的紧密，使节理间距分布具有较大的方差和偏度。
[1] In bedded sedimentary or mechanically anisotropic rocks, joints often occur in laterally persistent, parallel sets with distinctive spacing attributes. Three of those attributes include a positively skewed distribution of joint spacings, a positive correlation between median spacing and mechanical layer thickness, and the tendency for rocks to appear saturated with joints and to show a ratio of layer thickness to median joint spacing near one. We identify total applied strain, mechanical interaction, joint propagation velocity, and flaws as key variables in the progressive jointing process, and we use a one-dimensional model of mechanically interacting joints to characterize the specific influence on joint spacing, of the number, sizes, and size distributions of flaws in rock. For a given flaw size distribution, the mode flaw size has no effect on spacing distribution shape, median spacing, or saturation. Layers with fewer flaws approach saturation more slowly and reach it with fewer joints and larger median joint spacing. The joint spacing distributions in these layers have variance and skewness that may be 1–3 orders of magnitude larger than in layers with greater numbers of flaws. Flaw size range affects the rate at which a jointing layer approaches saturation but not the number of joints at saturation. Resulting spacing distributions are similar, although narrow flaw size ranges tend to promote greater numbers of closely spaced joints. The skewness of a flaw size distribution affects the rate at which layers approach saturation, as well as the shape of the resulting joint spacing distribution at saturation. Negatively skewed flaw size distributions promote close joint spacing and create spacing distributions with greater variance and skewness.