Geotechnical classification of sediments — Soil liquefaction — Seabed sediments with grain size distributions that are prone to soil liquefaction Drilling data analysis in 1 m GOK

The map of soil liquefaction potential provides information on the spread of sediments on the surface of the seabed, which, due to their specific grain size distributions, can tend to liquefy soil under external lastein effect (creation of pore water overpressure). The sediments are usually narrowly graded coarse sludge to medium sands. The effect of soil liquefaction can be important in construction projects and structures, such as pipelines and submarine cables on the seabed. The map covers the area of the entire German North Sea in scale 1: 250,000 with a statement on the sediments of the upper 0.2 m from the seabed surface. Two additional maps show results of the analysis of drill data in depths of 1 m and 2 m below seabed. The map is based on sediment samples of the seabed surface up to a depth of 0.2 m, as well as layer descriptions of drilling in the above-mentioned depths, which were available until April 2012. The basic data is stored in databases at the BSH and LBEG, and data collected in the future will be integrated into it. The curler sediments are classified according to their grain sizes according to DIN EN 14688-1: Clay (grain size < 0.002 mm); Schluff (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). On the basis of the grain size analyses carried out in the laboratory, the layer descriptions from drilling and grain sorting, the sediments are classified on the basis of the classification of STUDER &amp; KOLLER (1997). The legend includes two classes, soil liquefaction “potentially possible” and “not to be expected”.