Abstract A constant-head step injection test using a conventional straddle-packer system was performed for a normal fault in siliceous mudstone. The test applied a new method whereby axial displacements of isolated test sections in a borehole during injection are monitored by measuring the pressures of sliding packers and the pore pressure in the test section. The measured pressures and axial displacement, and the injection flow rate, were used to estimate the hydraulic aperture, shear displacement, normal compliance, normal stress, shear stiffness and hydraulic dilation angle of the fault during the test. The injection successfully yielded a large shear displacement during normal faulting of up to 13.3–49.5 mm (including the estimation error), which left residual shear displacement of 2.8–10.4 mm after a remarkable shear-slip event. The shear stiffness during faulting is estimated to be 2.3 × 107 to 8.4 × 107 Pa m−1 (considering the estimation error), which is consistent with empirically predicted values based on previous studies. The hydraulic dilation angle was inferred to be effectively zero as the residual shear displacement did not leave any increase in hydraulic aperture. The experimental method applied here does not require specialized equipment and could aid in the investigation of the hydromechanical behavior of subsurface fractures or aquifers.

中文翻译：

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作为钻孔引伸计的传统跨式滑动封隔器系统：在注入测试期间监测断层的剪切位移

摘要 对硅质泥岩中的正断层进行了使用传统跨式封隔器系统的恒水头阶跃注入试验。该测试采用了一种新方法，通过测量滑动封隔器的压力和测试段的孔隙压力，监测注入过程中钻孔中孤立测试段的轴向位移。测得的压力和轴向位移以及注入流量用于估计测试过程中断层的水力孔径、剪切位移、法向柔量、法向应力、剪切刚度和水力膨胀角。注入成功地在正断层期间产生了高达 13.3-49.5 毫米（包括估计误差）的大剪切位移，在显着的剪切滑移事件后留下了 2.8-10.4 毫米的残余剪切位移。断层期间的剪切刚度估计为 2.3 × 107 至 8.4 × 107 Pa m-1（考虑估计误差），这与基于先前研究的经验预测值一致。水力膨胀角被推断为实际上为零，因为残余剪切位移没有留下水力孔径的任何增加。这里应用的实验方法不需要专门的设备，可以帮助研究地下裂缝或含水层的流体力学行为。水力膨胀角被推断为实际上为零，因为残余剪切位移没有留下水力孔径的任何增加。这里应用的实验方法不需要专门的设备，可以帮助研究地下裂缝或含水层的流体力学行为。水力膨胀角被推断为实际上为零，因为残余剪切位移没有留下水力孔径的任何增加。这里应用的实验方法不需要专门的设备，可以帮助研究地下裂缝或含水层的流体力学行为。