Fascine Mattress Placement
Extensive fascine mattresses are nowadays mechanically sunk within a remarkably short time and with great accuracy. Fascine mattress placement has undergone modernisation in recent years. This is done by floating the mattress to the site, transferring it to the stationed support pontoon with the sinking-pipe attaching it to the sinking-beam of the stone dumping vessel. The mattress is precisely positioned with the help of a satellite navigation system (DGPS). Then the beam - anchored against the current - is lowered onto the bed, followed by the mattress with riprap ballast. The ballast is applied using a rockfiller. While the rockfiller moves over the mattress, the riprap is uniformly discharged by hydraulically powered shields. When the lowering operation is completed, lowering beam and cylinder are disengaged under water and retrieved. Then the rockfiller or a spud-rigged pontoon is used to deposit riprap on the mattress in the required thickness.