Hazard warning card Lower Saxony 1: 50 000 — Setting and Lifting Sensitive Building Ground (WMS Service)

The hazard warning card Lower Saxony 1: 50 000 — Setting and lifting-sensitive building ground (ISHB50) is from Geological Map 1: 50 000 (GK50) and engineering geological map 1: 50 000 (IGK50) derived, many years of regional experience and ground-mechanical analysis are taken into account in the preparation of the map. The map shows the spatial distribution of the various building ground types that are sensitive to setting and elevation up to 2 m depth. Underlying layers cannot be derived from the GK50 and the IGK50. For this purpose, the drilling database of the LBEG can provide further information and data. With the help of criteria and rules, the structure, composition, formation of the geological unit as well as its soil mechanical stiffness, strength and water sensitivity are evaluated as a building ground in terms of sensitisation and lifting sensitivity. Geological units with similar properties are summarised. Areas with load-dependent settlements in the expectation area of well-sustainable building land have been identified accordingly. 1.) high sensitivity due to high organic content and/or liquid to soft consistency 2.) medium to large sensitisation due to very low stiffness (fluviatile, brackish, marine sediments such as Klei) 3.) low to medium sensitisation due to low stiffness such as loess clay, auelehm (marine, brackish and fluviatile sediments) 4.) Low to large settling sensitivity and low to large settlement differences due to alternating stiffness 5.) Low to medium sensitisation/lifting sensitivity of clay and clay rocks by shrinking/sources (water content changes), lifting by crystallisation pressure (as a result of pyrite weathering/gip formation) 6.) Sensitive (volume increase) when water enters by converting anhydrite into plaster 7.) sensitive to lowering due to the solubility of plaster when water enters 8.) usual load-dependent settlements of well-bearing loose rocks and solid rocks General information on settlements and lifts can be extracted from the building ground types and targeted project-related investigations can be planned. So far, lifting symptoms have only been observed in a few cases, mostly as a result of the source properties of clays. Lifting as a result of gypsum crystal growth in the weathering range of clay stones has only been observed in individual cases. The IHSB50 cannot replace ground tests according to DIN EN 1997-2:2010-10, DIN EN 1997-2/NA:2010-12 and DIN 4020:2010-12.