N_ZONE_ALEA_PPRN_20140309_S_032

The mapping of the hay removal of clays in the commune of Saint-Justin 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）编制的热尔省官方制图，涉及热尔省圣屈斯坦公社内黏土收缩-膨胀灾害的相关制图。该制图为黏土收缩-膨胀现象发生概率的分区图。法国地质矿产调查局（BRGM）首先基于纯物理准则，利用该省的地质图编制了易感性图，编制过程中针对每个地质单元，综合考量了以下因素： — 地质单元内黏土物质的占比（岩相分析）； — 黏土相内膨胀性矿物的占比（矿物组成分析）； — 该物质的岩土工程特性。 针对已识别的每个黏土地质单元，最终的灾害等级由上述易感性等级结合灾害性胀缩密度确定，该密度以每100平方公里实际出露的城市化地表为统计基准。