Experimental Study on Cutting Hard Soil with New Hob Draghead of TSHD

As the main construction vessel of dredging project, the TSHD (trailing suction hopper dredger) has low efficiency when dredging hard soil. It is because that the cutting depth of the draghead is limited, the concentration of suction slurry is low. Therefore, researchers propose a new draghead scheme, which changes the traditional mode of horizontal movement of single row of teeth into the mode of rotary cutting with multiple rows of teeth, which can greatly increase the cutting depth and dredging efficiency. At the same time, the new cutting method has also brought great changes to the structure and process parameters of the whole draghead. But in fact, researchers have little understanding of the cutting mechanical behavior and the corresponding process parameters, and the hob draghead is far from achieving field application. Through laboratory experiments, this paper analyzes and grasps the influence law of several key factors such as soil cutting depth, hob rotation rate and moving speed on hob cutting effect within the range of construction parameters. The experiment results show that the deeper the hob is embedded in the soil, the greater the force on the rake teeth and the power consumed. The increase of hob rotation rate can greatly reduce the force on the rake teeth, but the total required power increases a little. The lower the rotation rate, the larger the block or slice after soil failure, and the greater the probability of large instantaneous cutting force. Reducing the moving speed can quickly reduce the cutting torque and power. Although increasing the cutting depth, hob rotation rate and reducing the ship forward speed can effectively improve the dredging efficiency of the draghead, it is worth noting that these factors are limited by the equipment and operation of the suction dredger. For example, the TSHD needs a certain speed to maintain its heading stability, and the power of the ship's main engine needs to be reasonably distributed. Therefore, the research and development of the new hob draghead is a complex and systematic research work. The research results of this paper can provide important references for the structural design and the determination of process parameters of the new draghead.