Abstract This work presents for the first time associated thermal anomalies and deformations over subsurface cavities/voids located within two harbour quays in Le Havre Harbourg, Normandy, France. An U.A.V. (Unmanned Aerial Vehicle) was used to acquire visible and thermal images over a diurnal cycle (from 7 a.m. to 5 p.m.). The visible images were processed to realize an altimetric model of the platforms by mean of the photogrammetric method, while the thermal infrared (TIR) images were used to study the evolution of their surface temperatures. The obtained 3D model shows the location of five topographic depressions on both quays. The analysis of the evolution of the surface thermal field leads to the detection of cold thermal anomalies that are (1) not correlated to surface properties, and (2) spatially associated to the flanks of the five topographic depressions. Using a 2D conductive-radiative model, we show that these anomalies are not directly due to the thermally insulating effect of an air-filled area. Finally, we conclude that preferential infiltration and subsequent evaporation in the micro-fracturation present within the flanks of the depressions may be responsible for the strong cooling of these zones.

中文翻译：

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根据基于无人机的多时相红外和可见光图像推断，渗透率和空隙对热信号的影响

摘要 这项工作首次展示了位于法国诺曼底勒阿弗尔港的两个港口码头内的地下空洞/空隙的相关热异常和变形。UAV（无人驾驶飞行器）用于获取昼夜循环（从早上 7 点到下午 5 点）的可见光和热图像。通过摄影测量方法处理可见光图像以实现平台的高度模型，而热红外（TIR）图像用于研究其表面温度的演变。获得的 3D 模型显示了两个码头上五个地形洼地的位置。对地表热场演化的分析导致检测冷热异常，这些异常 (1) 与地表特性无关，(2) 在空间上与五个地形洼地的侧翼相关。使用 2D 传导辐射模型，我们表明这些异常现象并非直接由充满空气的区域的绝热效应引起。最后，我们得出结论，凹陷侧翼内存在的微裂缝中的优先渗透和随后的蒸发可能是这些区域强烈冷却的原因。