In addition to dredging waterways and building ports, the scope of use of dredgers is also expanding. Now it has been used to excavate the foundations of hydraulic structures (such as docks, docks, gates, etc.), open canals, build embankments, reclaim land, mine mineral deposits, reclaim fields, lay underground pipelines, etc., making it an important engineering vessel.
The types of dredgers can be divided into two categories according to their working principles, namely mechanical type and hydraulic type, the former is also known as dry digging type, and the latter is also known as wet digging type.
The mechanical dredger system uses various buckets or shovels to dig mud, sand and gravel, including grab bucket type, bucket type and chain bucket typeThe hydraulic dredger uses a centrifugal pump to suck mud (a mixture of mud, sand and water) for dredging, in the form of suction type, cutter suction type and rake suction type.
In order to meet the needs of coastal harbors and increase their ability to resist wind and waves, many self-propelled grab dredgers have been built abroad, which have mud tanks and can be self-digging, self-loading, self-transporting and self-unloading. Japan has built the world's largest self-propelled grab dredger, which is 60 meters long, 80 meters deep, can lift 150 tons, can dig 20 meters outboard water, can grab 25 cubic meters of hard soil in one bucket, and weighs 125 tons, which is really a behemoth in its kind.