Underground service duct construction in high water level areas - using part cylindrical steel boards rotated in and out of soil, prior to adding cement mixt. to duct wall

摘要

The duct is formed as a slot or groove, and has the shape of a part of a cylindrical surface with an axis running approximately parallel to the soil surface. It can be made of various substances, such as clay cement, metal and has reinforcements incorporated. Normally, it is prefabricted. The duct is fixed into position by soil anchor fixtures which are fitted tangentially to the cylindrical surface. In installation, a board is used which also has the shape of a part cylindrical surface, and is placed above the soil surface so that the cylinder axis likewise runs above ground surface with a clearance which is less than the cylinder's radius.