The effects on seismic waves of interconnected nearly aligned cracks
The effects on seismic waves of interconnected nearly aligned cracks
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DOI：
10.1046/j.1365-246x.2001.00451.x
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发表时间：
2001-07
影响因子：
2.8
通讯作者：
S. Tod
中科院分区：
文献类型：
--
作者：
S. Tod
在地震波通过的过程中，可能会发生流体在相连的裂缝之间的转移。这种流体流动可以使用有效介质理论的扩展来建模（哈德逊等人，1996），并且通过非顺应性孔隙来实现。流动由代表裂纹之间压力平衡的松弛时间的参数τ控制。然而，如果裂纹完全对齐并且具有相同的纵横比，则该理论产生意想不到的结果，即在低频率下，裂纹被有效地隔离，并且在高频率下，它们被完全排出。该模型的人为限制，完全对齐的裂纹相同的纵横比被认为是造成这一结果的原因。通过修改模型，使裂纹的方向和纵横比的变化，我们看到，一个更现实的模型具有通常的属性，其中裂纹是孤立的在高频率和不排水在低频率。我们选择的纵横比分布与观测结果一致（Hay等，1988）。通过无量纲参数Ωτ，可以看出，衰减系数与频率有关。
SUMMARY Transfer of fluid between connected cracks may occur during the passage of seismic waves. Such fluid flow can be modelled using an extension of effective medium theory (Hudson et al. 1996) and is effected via non-compliant pores. The flow is governed by a parameter τ representing the relaxation time of pressure equalization between cracks. However, if the cracks are fully aligned and have the same aspect ratio, the theory produces the unexpected result that, at low frequencies, the cracks are effectively isolated and at high frequencies they are fully drained. The artificial restriction of the model to perfectly aligned cracks of identical aspect ratio is seen to be the cause of this result. By reworking the model to allow the crack orientation and aspect ratios to vary, we see that a more realistic model has the usual properties in which the cracks are isolated at high frequencies and undrained at low frequencies. We have chosen the distributions of aspect ratios to be in agreement with observation (Hay et al. 1988) . Thomsen's parameters (Thomsen 1986) and the attenuation coefficients are seen to be frequency-dependent via the non-dimensional parameter Ωτ.