Several experimental studies, carried out on anisotropic rocks, have evidenced that even though strains, due to isotropic loading and/or internal fluid pressure, are strongly anisotropic, the resulting Biot’s tensor is almost isotropic. Those results were found on two different rocks: a clay rock (France—Bure argillite) and a sandstone from the Vosges region (France). Such (a priori) surprising results led us to develop micromechanical modelling in which anisotropy comes either from an anisotropic solid matrix (and isotropic pore space) or from an anisotropic pore space (and isotropic solid matrix). The obtained results have shown that for both cases the Biot’s tensor is virtually isotropic or presents a very weak anisotropy. This unambiguously supports the fact that a strongly anisotropic porous material is compatible with experimental measurements of isotropic (or quasi isotropic) Biot’s tensor.

中文翻译：

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各向异性多孔岩石的准各向同性 Biot 张量：实验和微观力学建模

在各向异性岩石上进行的几项实验研究表明，即使由于各向同性载荷和/或内部流体压力而产生的应变是强各向异性的，但由此产生的 Biot 张量几乎是各向同性的。这些结果是在两种不同的岩石上发现的：粘土岩（法国-Bure 泥质岩）和孚日地区（法国）的砂岩。这种（先验的）令人惊讶的结果使我们开发了微机械建模，其中各向异性来自各向异性固体基质（和各向同性孔隙空间）或来自各向异性孔隙空间（和各向同性固体基质）。获得的结果表明，对于这两种情况，Biot 的张量实际上是各向同性的或呈现出非常弱的各向异性。