Quality control of jet grouting at large depth is a challenging task. An in-hole electrical resistivity method was recently shown to have high potential for assessing the diameter and integrity of jet grouting. To facilitate visualised inspection and practical use of the in-hole resistivity method for jet grouting, this study introduces a novel and practical tomographic approach. An analogous mapping approach from axially symmetric in-hole electrical resistivity tomography (ERT) to two-dimensional (2D) half-space surface ERT is proposed, allowing direct implementation of widely available 2D inversion software. A quantitative reduction method is also proposed to determine accurately the variation of column diameter from the inverted tomogram. Numerical simulations validate the proposed approach and show that the estimation error is within 10% when the electrode spacing is less than 1/5 of the column diameter. The spatial resolution and the effect of axially asymmetric condition are numerically investigated, the latter suggesting the importance of centralising electrodes in the soilcrete column. Two physical model tests are performed and verify the performance of the proposed method experimentally.

中文翻译：

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孔内电阻层析成像技术评估土工混凝土柱直径

大深度喷射注浆的质量控制是一项艰巨的任务。最近显示，一种井内电阻率法具有很高的潜力，可用于评估旋喷灌浆的直径和完整性。为了促进可视化检查和井内电阻率法在喷射注浆中的实际应用，本研究引入了一种新颖且实用的层析成像方法。提出了一种类似的映射方法，从轴向对称的孔内电阻率层析成像（ERT）到二维（2D）半空间表面ERT，可以直接实现广泛使用的2D反演软件。还提出了一种定量减少方法，以根据倒排的层析X射线照片准确地确定色谱柱直径的变化。数值模拟验证了该方法的有效性，并表明当电极间距小于色谱柱直径的1/5时，估计误差在10％以内。数值研究了空间分辨率和轴向不对称条件的影响，后者表明了在土混凝土柱中集中电极的重要性。进行了两个物理模型测试，并通过实验验证了所提出方法的性能。