Columnar jointed basalt is widely distributed in the dam foundation and underground cavern of the Baihetan hydropower station, in which columnar jointing and microfractures are developed, the integrity of the rock mass is poor, and the material easily relaxes after excavation. Therefore, it is important to obtain the real mechanical parameters of columnar jointed basalt in rock mechanics problems. In the test cave at the dam site, six in situ samples with a size of 50 cm × 50 cm × 100 cm were successfully made, and in situ true triaxial test were carried out. This paper presents a method for obtaining the strength parameters of the Mohr–Coulomb criterion and Hoek–Brown criterion by true triaxial testing. The peak strength parameters under three states and yield strength parameters under one state were obtained by setting various stress paths for the undisturbed samples and failure samples. The strength characteristics of columnar joint basalt and the crack characteristics of the specimens are analyzed, and the results of the triaxial test and direct shear test are compared. By means of acoustic emission (AE) techniques and surface crack descriptions, the failure process and failure pattern of the samples were obtained. The abundant test results provide strong support for the selection of engineering rock mechanics parameters.

中文翻译：

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白鹤滩水电站柱状节理玄武岩真三轴仪强度特性研究

白鹤滩水电站坝基和地下洞室中柱状节理玄武岩广泛分布，柱状节理和微裂缝发育，岩体整体性差，开挖后材料容易松弛。因此，在岩石力学问题中获得柱状节理玄武岩的真实力学参数具有重要意义。在坝址试验洞内，成功制作了6个50 cm×50 cm×100 cm的原位试样，并进行了原位真三轴试验。本文提出了一种通过真三轴试验获得 Mohr-Coulomb 准则和 Hoek-Brown 准则强度参数的方法。通过对原状试样和破坏试样设置不同的应力路径，得到三种状态下的峰值强度参数和一种状态下的屈服强度参数。分析了柱状节理玄武岩的强度特征和试件的裂纹特征，并比较了三轴试验和直剪试验的结果。通过声发射（AE）技术和表面裂纹描述，获得了样品的失效过程和失效模式。丰富的试验结果为工程岩石力学参数的选取提供了有力的支持。并比较了三轴试验和直剪试验的结果。通过声发射（AE）技术和表面裂纹描述，获得了样品的失效过程和失效模式。丰富的试验结果为工程岩石力学参数的选取提供了有力的支持。并比较了三轴试验和直剪试验的结果。通过声发射（AE）技术和表面裂纹描述，获得了样品的失效过程和失效模式。丰富的试验结果为工程岩石力学参数的选取提供了有力的支持。