N_ZONE_ALEA_PPRN_20140386_S_032

The mapping of the hay removal of clays in the commune of Saint-Paul-de-Baïse in the Gers department is extracted from the departmental mapping from the BRGM. This mapping is a zoning of the probability of occurrence of the phenomenon of shrink-inflating of clay soils. A susceptibility map was first drawn up on the basis of purely physical criteria by the BRGM from the geological maps of the department, which were interpreted taking into account the following factors for each geological formation: — the proportion of clay material within the formation (lithic analysis); — the proportion of blowing minerals in the clay phase (mineralogical composition); — the geotechnical behavior of the material. For each of the clay formations identified, the hazard level is ultimately the result of the level of susceptibility thus obtained with the density of sinister swelling, reported to 100 km² of actual urbanised outcropping surface.本数据集提取自法国地质矿产调查局（Bureau de Recherches Géologiques et Minières，BRGM）编制的热尔省区域地质图，涵盖热尔省圣波尔德拜斯市镇范围内的黏土胀缩现象分布制图成果。该成果为黏土土壤胀缩现象发生概率的分区图。法国地质矿产调查局首先以该省地质图为基础，依据纯物理准则编制了敏感性分布图；编制过程中针对各地质单元，综合考量了以下因素：— 地层内黏土物质占比（岩性分析）；— 黏土相中膨胀性矿物占比（矿物组成）；— 该物质的岩土工程特性。针对已识别的每一处黏土地层，最终的灾害等级由上述敏感性等级结合胀缩灾害密度确定，该密度以每100平方千米的实际出露城市化地表面积为统计基准。