Abstract The strength of rock or rock mass is needed for the design of mining and geotechnical engineering structures. Pioneer laboratory works stimulated the interest of developing 3D rock failure criteria with the consideration of the effect of the intermediate principal stress (σ2). However, the variability among some of the test data obtained under different testing conditions hampered the usefulness of these test data. In this study, a FEM tool is utilized to quantify platen-induced σ2 effects in the σ2 range of σ3 ≤ σ2 ≤ 1/2σ1. It is proposed that the intrinsic 3D rock strength envelopes within the range of σ3 ≤ σ2 ≤ 1/2σ1 can be obtained by excluding the end-effect-induced strength increase from the laboratory true triaxial compression test results. The proposed method is checked against laboratory test results of two types of rocks where applied stresses were kept the same with different rock-platen contact conditions. In the end, an approach to determine 3D failure envelopes in the full σ2 range of σ3 ≤ σ2 ≤ σ1 is proposed. This study offers insight into how to better interpret laboratory true triaxial compression test results for developing 3D failure criteria of rock.

中文翻译：

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一种消除最终效应的方法，用于确定固有 3D 岩石强度包络线

摘要 采矿和岩土工程结构的设计需要岩石或岩体的强度。先锋实验室工作激发了开发 3D 岩石破坏标准并考虑中间主应力 (σ2) 影响的兴趣。然而，在不同测试条件下获得的一些测试数据之间的可变性阻碍了这些测试数据的有用性。在这项研究中，有限元工具被用来量化在 σ3 ≤ σ2 ≤ 1/2σ1 的 σ2 范围内的压板引起的 σ2 效应。提出在 σ3 ≤ σ2 ≤ 1/2σ1 范围内的固有 3D 岩石强度包络线可以通过从实验室真三轴压缩试验结果中排除端效应引起的强度增加来获得。所提出的方法与两种岩石的实验室测试结果进行了比较，其中施加的应力在不同的岩石-平台接触条件下保持相同。最后，提出了一种在 σ3 ≤ σ2 ≤ σ1 的整个 σ2 范围内确定 3D 失效包络的方法。这项研究提供了有关如何更好地解释实验室真实三轴压缩测试结果以开发岩石 3D 破坏标准的见解。