Effective‐medium theories for fluid‐saturated materials with aligned cracks
Effective‐medium theories for fluid‐saturated materials with aligned cracks
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DOI：
10.1046/j.1365-2478.2001.00272.x
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发表时间：
2001-09
影响因子：
2.6
通讯作者：
J. Hudson;T. Pointer;E. Liu
中科院分区：
文献类型：
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作者：
J. Hudson;T. Pointer;E. Liu
如果裂纹的数量密度很小，则不同的理论之间存在普遍的一致性，这些理论给出了具有干燥、对齐裂纹的材料的整体性能的表达式。对于充满流体的孤立裂缝也有非常公平的一致。然而，对于具有等孔隙率的流体填充裂缝，两种不同的理论之间存在相当大的差异。与最近发表的合成砂岩实验数据的比较表明，与干燥样品的理论非常吻合。然而，尽管实验室样品中的裂纹数密度不太可能适用一阶理论，但正确到二阶（数密度）的表达式提供了更差的拟合。波长与裂纹尺寸之比似乎还不够大，无法与有效介质理论进行详细比较，有效介质理论只有在该比值很大时才有效。数据显示了干裂纹和散射的色散效应，这两种效应在足够长的波长下都不会发生。来自水饱和样品的数据表明，等孔隙率的影响是显着的，尽管两种理论在显着程度方面存在很大差异。再次，尽管有上述保留，理论与观察之间的合理契合还是可以被证明的。
There is general agreement between different theories giving expressions for the overall properties of materials with dry, aligned cracks if the number density of cracks is small. There is also very fair agreement for fluid‐filled isolated cracks. However, there are considerable differences between two separate theories for fluid‐filled cracks with equant porosity. Comparison with recently published experimental data on synthetic sandstones gives a good fit with theory for dry samples. However, although the crack number density in the laboratory sample is such that first‐order theory is unlikely to apply, expressions correct to second order (in the number density) provide a worse fit. It also appears that the ratio of wavelength to crack size is not sufficiently great for any detailed comparison with effective‐medium theories, which are valid only when this ratio is large. The data show dispersion effects for dry cracks and scattering, neither of which will occur at sufficiently long wavelengths. Data from the water‐saturated samples indicate that the effect of equant porosity is significant, although the two theories differ strongly as to just how significant. Once again, and in spite of the reservations mentioned above, a reasonable fit between theory and observation can be shown.