In laboratory rock mechanics experiments, it is common practice to employ single-component acoustic emission (AE) sensors to monitor the rock fracturing process, where the fracture location and fracturing mechanism can be inverted from the single-component AE waveforms. However, since such applications are often based on simplified isotropic hypotheses, accurately capturing the influence of strong anisotropy in rock on particle vibrations at rock surfaces using single-component AE sensors remains challenging. This limitation biases the actual particle vibration amplitude and direction, potentially leading to erroneous estimations in AE waveform inversion mof rock fracturing. Here, we combined three piezoelectric discs to create a three-component AE sensor, allowing us to capture particle vibration along three sensing directions on rock surfaces. Through two calibration experiments and polarization analysis of the three-component waveforms, we verify the new sensor's capability to reliably capture the vibration features of hypocenters that are not easily obtainable using a single-component sensor. We apply this new sensor in uniaxial compression tests on shale, a material known for its strong anisotropy. The results indicate that the AE behaviors monitored by the three-component sensor are consistent with those obtained from the widely used single-component sensor. Moreover, the polarization analysis of the three-component waveforms reveals the presence of coupled hypocenters associated with multiple fractures. This is the first time a three-component AE sensor is used in laboratory rock mechanics experiments, which offers a more comprehensive understanding of the dynamic evolution of fractures in rock formations.

中文翻译：

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三分量声发射传感器在岩石力学实验中的应用


在实验室岩石力学实验中，通常采用单分量声发射（AE）传感器来监测岩石破裂过程，可以从单分量声发射波形反演破裂位置和破裂机制。然而，由于此类应用通常基于简化的各向同性假设，因此使用单分量声发射传感器准确捕获岩石中强各向异性对岩石表面粒子振动的影响仍然具有挑战性。这种限制使实际粒子振动幅度和方向产生偏差，可能导致岩石破裂声发射波形反演中的错误估计。在这里，我们结合了三个压电盘来创建一个三组件 AE 传感器，使我们能够捕获岩石表面沿三个传感方向的粒子振动。通过两次校准实验和三分量波形的偏振分析，我们验证了新传感器能够可靠地捕获震源的振动特征，而使用单分量传感器不容易获得这些特征。我们将这种新型传感器应用于页岩的单轴压缩测试，页岩是一种以其强各向异性而闻名的材料。结果表明，三分量传感器监测到的声发射行为与广泛使用的单分量传感器获得的声发射行为一致。此外，三分量波形的偏振分析揭示了与多个裂缝相关的耦合震源的存在。这是三分量声发射传感器首次应用于实验室岩石力学实验，可以更全面地了解岩层裂缝的动态演化。