DATA_Multi_stages_loading_and_relaxing_of_double_torsion

Based on linear elastic fracture mechanics, we performed several double torsion tests using shale samples with various initial stress levels under constant loading displacement. The pre-set initial stress levels were selected as 34%, 54%, 72% and 94% of the pre-cracking load. These initial load were applied with a high rate of 2.7 mm/min first and then the natural load relaxation occured. At certain moment, we dripped water into crack tip zone to capture the subcritical crack growth induced by water-rock interaction, exactly referred to clay hydration, which could create damage and accelerate crack growth. Hereafter, water diffused into the external environment, which caused the potential crack healing. Specifically, the crack healing can make the monitored load increase, which is a representive signal for this. The dataset here is a complete recording with a raw data sensing under different loading stages.本研究基于线弹性断裂力学（linear elastic fracture mechanics），采用不同初始应力水平的页岩试样，在恒定加载位移条件下开展了多组双扭试验（double torsion tests）。预设初始应力水平选取为预开裂荷载的34%、54%、72%与94%。试验首先以2.7 mm/min的高速施加各初始荷载，随后发生自然荷载松弛。在试验过程中的特定时刻，我们向裂纹尖端区域滴水，以捕捉由水-岩相互作用（water-rock interaction）诱发的亚临界裂纹扩展，该过程确切对应黏土水化（clay hydration）作用，可造成岩体损伤并加速裂纹扩展。此后，水分扩散至外部环境，进而引发潜在的裂纹愈合现象。具体而言，裂纹愈合可使监测得到的荷载值升高，这是表征该现象的典型信号。本数据集完整记录了不同加载阶段下的原始传感数据。