Narrow wall
The construction of a narrow wall is a method of special civil engineering for the introduction of vertical seals into the ground, which typically consists of alluvial sediments under groundwater .
Narrow walls are used to seal dams accompanying dams , and more rarely also to seal construction pits . Narrow walls are created to enclose contaminated sites such as contaminated floor areas and waste disposal facilities such as landfills in order to prevent contamination from being carried over into the surrounding groundwater.
Procedure
The narrow wall is an economical cut-off wall with a low wall thickness made of cement-bound , hardening sealant . The nominal thickness is 50 to 80 mm, less often 100 mm.
To produce a cress usually heavy steel piles are in the ground vibrated (more rarely pressed or rammed). While the pile is slowly pulled up again, the remaining under the pile shoe with a cavity is binder - suspension of cement , bentonite , or the like is pressed.. The increment is chosen so that the following plank stitch overlaps the previous one. The device is therefore advanced by a little less than the width of the plank to ensure that a continuous sealing element is created in the ground.
The sealing wall compound usually has a permeability coefficient of <10 −9 m / s and (like the application classes) is regulated according to the standard.
Alternatively, at depths of up to 10 meters, the narrow wall can also be created by milling a binding agent suspension into the ground.
scope of application
Narrow walls can only be produced where it is possible to drive steel profiles.
The thin wall cannot offer any resistance to horizontal floor movements. If an excavation pit is to be excavated directly on the wall , a sheet pile wall or reinforced concrete structure should be selected.