Subgrade

Called the planum (Latin planum = level, area), including subgrade or grading, a surface flat (plan) manufactured, held at the ( more ) construction is. The term exists both in building construction and civil engineering, but is also used in archeology to refer to a newly created search area use. Sometimes a distinction is made (eg as a result of removal and backfilling ) and final grade (after processing and landfill ) between rough subgrade.

The preparation of the subgrade is done either in small areas by hand or over large areas with the help of bulldozers or graders. The compression is performed with vibrating plates or roller trains.

Application

In building construction, flat and well compacted areas are required in order to produce clean and firm foundations can. The subgrade can be considered in this case as the bottom of the pit.

The Transportation Infrastructures the planum forms the upper end of the earth structure and thus represents an interface between substructure and superstructure dar. In contrast to the construction, the subgrade beneath roads to one side ( cross slope ) to ensure drainage and prevent softening of the Erdbauwerkes. The subgrade is in the incision, ie below the ground surface, a lateral drainage is additionally arrange ( for example, using a Sickerstranges ). In railway construction, the so-called formation protection layer can be found below the subgrade. In road is above the subgrade, the frost protection layer.

Requirements

To prevent damage to buildings and transport structures, the subgrade and the underneath layers must be sufficiently strong. For this purpose, viability studies are carried out during construction. Basically between test methods on site ( in situ ) and in the laboratory ( ex situ ) must be distinguished. Possible test methods for compaction control the subgrade and the underlying layers are for example:

• Plate load test
• Proctor
• CBR test

" Grading " in cities

In the development of Central European cities have been a hindrance to their growth the old city fortifications. Then the city wall was removed and leveled the city moat and built. So today's street names, such as the grading in Stuttgart explain ( there at the same time B 27) or grave road and grading ( Road ) in Sindelfingen.