It has been widely accepted that the Brazilian test can be used to obtain the indirect tensile strength of geo-materials. However, the effects of the contact conditions and the heterogeneity of the rock affect the micro-failure of the disc and the accuracy and feasibility of the Brazilian tensile strength (BTS), which typically leads to deviations from the results of the direct test. This study uses active and passive ultrasonic techniques and a three-dimensional flat-joint model (FJM3D) to quantitatively investigate the effects of these factors on the location and source mechanism with a Brazilian test, both in the laboratory and with numerical tests. During the laboratory tests, eight channels were used to record full waveform data continuously, and a total of 1090 and 928 acoustic emission (AE) events were located successfully under line loads and non-line loads, respectively. Both cases showed that the crack initiation points occurred away from the centre of the disc, indicating that the true tensile strength value may be somewhat underestimated. Three classification methods based on moment tensor inversion were used to quantitatively study the AE source analysis, which revealed that tensile micro-cracks that contain some deviatoric components predominantly occurred in micro-failure events. With the use of the FJM3D, the effects of the contact conditions and the heterogeneity of the rocks were analysed in detail. Four types of numerical tests were performed with different contact conditions and degrees of heterogeneity for comparison, indicating that the heterogeneity of rocks has a remarkable effect on the distribution of horizontal stress. This microcosmic and quantitative perspective can provide new data that can be used to modify the Brazilian test to obtain more accurate tensile strength values.

人们普遍认为，巴西试验可用于获得土工材料的间接拉伸强度。但是，接触条件和岩石异质性的影响会影响圆盘的微观破坏以及巴西拉伸强度（BTS）的准确性和可行性，这通常会导致与直接测试结果产生偏差。这项研究使用主动和被动超声技术以及三维平面接头模型（FJM3D），通过实验室和数值测试中的巴西测试定量研究了这些因素对位置和源机理的影响。在实验室测试期间，使用了八个通道连续记录完整的波形数据，分别在线负载和线负载下分别成功定位了1090和928个声发射（AE）事件。两种情况都表明，裂纹的起始点出现在远离圆盘中心的位置，这表明真实的抗拉强度值可能会被低估。三种基于矩张量反演的分类方法被用于定量研究声源分析，结果表明，在微破坏事件中，主要包含一些偏斜分量的拉伸微裂纹发生了。使用FJM3D，详细分析了接触条件和岩石非均质性的影响。为了进行比较，在不同的接触条件和不均匀度下进行了四种类型的数值测试，表明岩石的非均质性对水平应力的分布有显着影响。这种微观和定量的观点可以提供新的数据，这些数据可以用来修改巴西测试以获得更准确的拉伸强度值。