Understanding the geological and hydrological conditions present within an unstable slope is crucial for assessing the likelihood of failure. Recently, geoelectrical characterization and monitoring of landslides has become increasingly prevalent in this context, due to the spatial sensitivity of electrical methods to critical hydro-mechanical parameters. We explore a situational relationship between resistivity and matric potential (or negative pore pressure), which is a key parameter in estimating the resistance to shear in geological materials, and gravimetric moisture content (GMC). We have chosen a well-characterized active landslide instrumented with geoelectrical monitoring technology, the Hollin Hill Landslide Observatory, situated in Lias rocks in the southern Howardian Hills, United Kingdom. We report on petrophysical relationships between porosity, GMC, electrical resistivity, and matric potential. We trial the application of these petrophysical relationships to inverted resistivity images. Ground model development is achieved through a mixture of clustering resistivity distributions and analysis of surface movements. Our findings show the shrink swell properties of clay result in a variable porosity, which is problematic for applying classic petrophysical relationships documented in the literature. Moreover, directly translating resistivity distributions into matric potential has additional challenges. Nonetheless, volumetric imaging of resistivity suggest that low shear strengths are concentrated downslope of a rotational backscarp. We infer that an accumulation of moisture drives the development of a slip surface at depth, which subsequently manifests in failure at the ground surface. We conclude that the time-lapse resistivity images alone could not be used to infer the pore pressure conditions present within the slope without development of the petrophysical relationships shown here. Therefore, we suggest that the results have practical implications for landslide monitoring with geophysical methods.

中文翻译：

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在富含粘土的滑坡上使用岩石物理学和地电方法的实际考虑


了解不稳定斜坡内的地质和水文条件对于评估破坏的可能性至关重要。最近，由于电方法对关键水力参数的空间敏感性，滑坡的地电表征和监测在这方面变得越来越普遍。我们探索了电阻率和基质势（或负孔隙压力）之间的情境关系，基质势是估算地质材料抗剪力和重量含水量（GMC）的关键参数。我们选择了一个配备有地电监测技术的特征明确的活动滑坡——霍林山滑坡观测站，该观测站位于英国霍华德山南部的利亚斯岩石中。我们报告孔隙度、GMC、电阻率和基质势之间的岩石物理关系。我们尝试将这些岩石物理关系应用于反演电阻率图像。地面模型的开发是通过结合电阻率分布聚类和地表运动分析来实现的。我们的研究结果表明，粘土的收缩膨胀特性会导致孔隙率变化，这对于应用文献中记录的经典岩石物理关系是有问题的。此外，直接将电阻率分布转换为矩阵势还存在额外的挑战。尽管如此，电阻率的体积成像表明，低剪切强度集中在旋转后陡坡的下坡处。我们推断，水分的积累会驱动深层滑移面的形成，随后表现为地面的破坏。 我们得出的结论是，如果不发展此处显示的岩石物理关系，则不能仅使用延时电阻率图像来推断斜坡内存在的孔隙压力条件。因此，我们认为该结果对于利用地球物理方法监测滑坡具有实际意义。