N_ZONE_ALEA_PPRN_20140407_S_032

The mapping of the hay removal of clays in the commune of Bourrouillan 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.热尔省（Gers）布鲁利安市镇（Bourrouillan）内经干草移除处理的黏土绘图数据，源自法国地质与矿产研究局（BRGM）的省级绘图成果。该绘图为黏土土壤胀缩现象发生概率的分区图。法国地质与矿产研究局（BRGM）首先依托该省地质图，基于纯物理标准编制了易发性图件；该地质图的解译需结合各地质地层的以下影响因素：— 地层内黏土物质占比（岩性分析）；— 黏土相内吹蚀矿物占比（矿物组成分析）；— 该物质的岩土工程特性。针对已识别的各黏土地层，最终的灾害等级由上述易发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面积为统计基准。