N_ZONE_ALEA_PPRN_20140426_S_032

The mapping of the hay removal of clays in the commune of Lelin-Lapujolle 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.本次研究涉及的热尔省莱兰-拉普约勒市镇内黏土胀缩灾害的分区图件，数据源自法国地质矿产调查局（BRGM）编制的省级图件。该图件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）首先以热尔省地质图为基础，基于纯物理准则编制了敏感性分区图，编制过程中针对每个地质构造，综合考量了以下因素： — 地层内黏土物质占比（岩性分析）； — 黏土相内膨胀性矿物占比（矿物组成分析）； — 岩土体的工程地质特性。 针对所识别出的各黏土地层，最终的灾害等级由上述得到的敏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裸露地表为统计基准。