A new type of hob draghead, i.e. the so called hob draghead is developed to solve the excavating problem in dredging engineering. In this paper, based on the previous indoor tests of the new hob draghead in the non-submerged environment, the cutting tests in the submerged environment are further carried out. The test results show that the smaller the cutting thickness of the hob tooth is, the smaller the cutting force is, and the smaller the soil particles formed after cutting the hard clay are, the more conducive to suction and transportation. Besides, the influence of cutting torque and power varied with cutting depth, rotation rate and traction speed are investigated. In submerged environment, the cutting torque and power of hob are increased compared with those in non submerged environment. The research on underwater cutting of hob can provide an important research basis for the research on cutting hard clay by hob draghead, provide technical support for the design and optimization of hob draghead.
The TSHD (Trailing Suction Hopper Dredger) is one of the main operating ships in dredging engineering, and plays an important role in the reclamation of land from the sea, channel dredging, environmental dredging and other projects. As the most critical key dredging equipment, the draghead directly contacts with the soil, and play the role of excavation and crushing, which directly affects the efficiency and dredging capacity of the trailing suction dredger. For soft clay and sand, the cutting force of the draghead is small, and the transported particles are basically equivalent to the size of the soil itself. For hard clay, the shear strength of soil is high, and the required cutting force and cutting power are significantly increased. Moreover, the soil particles that have been cut are bound together and still retain a certain volume, which is equivalent to increasing the particle size of the transported particles. This will have adverse effects on the transportation system, such as easy to block the pump and pipe, resulting in shorter transportation distance, etc.
