Subsoil - Soil liquefaction potential German North Sea

The Soil Liquefaction Potential map presents information on the distribution of sediments at the seabed surface, which due to their specific grain size distributions, may be prone to soil liquefaction under external load effects (development of excess pore water pressure). The sediments are usually narrowly graded coarse silt to medium sands. The effect of soil liquefaction can be important for construction measures and structures, such as pipelines and submarine cables on the seabed. The map covers the area of the entire German North Sea at a scale of 1 : 250,000 with a statement on the sediments of the upper 0.2 m from the seabed surface. Two additional maps show the results of the evaluation of drilling data at depths of 1 m and 2 m below the seabed. The maps are based on sediment samples from the seabed surface down to a depth of 0.2 m as well as layer descriptions from drillings in the above-mentioned depth ranges, which were available until April 2012. The unconsolidated sediments are classified according to their grain sizes according to DIN EN 14688-1: Clay (grain size <0.002 mm); Silt (grain size 0.002 to 0.063 mm); Sand (grain size 0.063 to 2.0 mm); Gravel (grain size 2.0 to 63 mm); Stones and Blocks (grain size >63 mm). Based on the grain size analyses carried out in the laboratory, the layer descriptions from boreholes and the grain sorting, the sediments are classified on the basis of the classification of STUDER & KOLLER (1997). The legend includes two classes, soil liquefaction "potentially possible" and "not expected".

土壤液化潜力地图（Soil Liquefaction Potential map）展示了海床表面沉积物的分布情况，由于其特定的粒径分布特征，在外部荷载作用下（即超孔隙水压力发展过程中）易发生土壤液化。该类沉积物通常为窄级配粗粉砂至中砂。土壤液化效应对于海床之上的施工措施与构筑物（如管线、海底电缆等）具有重要影响。本地图以1:250000的比例尺覆盖整个德国北海海域，表征海床表面以下0.2米深度范围内的沉积物特征。另有两幅附属地图分别展示了海床以下1米与2米深度处的钻探数据评估结果。上述地图的数据基础为海床表面至0.2米深度的沉积物采样数据，以及上述深度范围内的钻探地层描述资料，相关数据的截止收集时间为2012年4月。未固结沉积物依据DIN EN 14688-1标准按粒径进行分类：黏土（粒径<0.002 mm）、粉砂（粒径0.002~0.063 mm）、砂（粒径0.063~2.0 mm）、砾石（粒径2.0~63 mm）以及石块与巨砾（粒径>63 mm）。结合实验室粒径分析结果、钻孔地层描述与颗粒分选特征，本数据集采用STUDER & KOLLER（1997）提出的分类体系对沉积物进行分类。该地图的图例包含两类土壤液化等级："潜在可能发生"与"预计不会发生"。