Accurate measurement of the evolution of rock joint void geometry is essential for comprehending the distribution characteristics of asperities responsible for shear and seepage behaviors. However, existing techniques often require specialized equipment and skilled operators, posing practical challenges. In this study, a cost-effective photogrammetric approach is proposed. Particularly, local coordinate systems are established to facilitate the alignment and precise quantification of the relative position between two halves of a rock joint. Push/pull tests are conducted on rock joints with varying roughness levels to induce different contact states. A high-precision laser scanner serves as a benchmark for evaluating the photogrammetry method. Despite certain deviations exist, the measured evolution of void geometry is generally consistent with the qualitative findings of previous studies. The photogrammetric measurements yield comparable accuracy to laser scanning, with maximum errors of 13.2% for aperture and 14.4% for void volume. Most joint matching coefficient (JMC) measurement errors are below 20%. Larger measurement errors occur primarily in highly mismatched rock joints with JMC values below 0.2, but even in cases where measurement errors exceed 80%, the maximum JMC error is only 0.0434. Thus, the proposed photogrammetric approach holds promise for widespread application in void geometry measurements in rock joints.

中文翻译：

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一种摄影测量方法，用于量化不同接触状态下岩石节理空隙几何形状的演变


准确测量岩石节理空隙几何形状的演变对于理解导致剪切和渗流行为的粗糙体的分布特征至关重要。然而，现有技术通常需要专门的设备和熟练的操作员，这带来了实际挑战。在这项研究中，提出了一种具有成本效益的摄影测量方法。特别是，建立局部坐标系是为了便于对准和精确量化岩石节理两半之间的相对位置。在不同粗糙度水平的岩石节理上进行推/拉测试，以产生不同的接触状态。高精度激光扫描仪可作为摄影测量方法评估的基准。尽管存在某些偏差，但测量到的空隙几何形状的演变总体上与先前研究的定性发现一致。摄影测量测量的精度与激光扫描相当，孔径最大误差为 13.2%，空隙体积最大误差为 14.4%。大多数关节匹配系数 (JMC) 测量误差低于 20%。较大的测量误差主要发生在JMC值低于0.2的高度失配的岩石节理中，但即使在测量误差超过80%的情况下，最大JMC误差也仅为0.0434。因此，所提出的摄影测量方法有望在岩石节理的空隙几何测量中得到广泛应用。