Dataset Direct Download Service (WFS): N_ZONE_ALEA_PPRN_20140159_S_032

The mapping of the hay removal of clays in the commune of Sirac 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（BRGM）制作的热尔省区域制图，其内容为热尔省锡拉克公社内黏土胀缩现象的相关制图。该制图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（BRGM）首先依托该省地质图，基于纯物理准则编制了易感性图，编制过程中针对每个地质构造，综合考量了以下因素： — 地层内黏土物质的占比（岩性分析）； — 黏土相内吹积矿物的占比（矿物组成）； — 材料的岩土工程特性。针对每一处已识别的黏土地层，最终的灾害等级由前述得到的易感性等级与灾害性胀缩密度共同确定，该密度以每100平方千米实际出露的城市化地表为统计基准。