During the dredging construction process, the trailing suction hopper dredger (TSHD) working in medium-long period waves often has a severe 6-DOF motion, which will generate force on the drag head and drag arm, then endangers the safety of the operation. Combined with the actual engineering situation, based on the CFD method, a series of numerical simulations were carried out on the motion of a 10,000-cubic-meter TSHD under the medium-long period waves. The motion(roll, pitch, pitch) under the sailing state and the dredging state was analyzed. Considering the influence of the drag arm and the travel of the wave compensator, the operation safety of the TSHD under medium and long period waves is discussed. The results show that the motion amplitude of TSHD is increased in medium-long period wave, and the motion of drag head may exceed the maximum travel of the wave compensator, which possibly cause danger.
Trailing suction hopper dredger (TSHD) is one of the two most mainstream ship types in the dredging industry today, and is widely used in dredging and remediation, channel excavation and maintenance, submarine tunnels and other projects. During the operation, the main working tools of the TSHD are the drag head and the drag arm. The drag arm is connected to the hull while the drag head is grounded. The drag head sucks the sediment into the suction pipe, enters the mud pump through the elbow, and finally discharges it into the spoil hopper of the TSHD through the mud pump.
Medium and long period waves, defined as waves with periods between tides and swells. In the near-port dredging engineering, it is inevitable for the TSHD to operate under medium-long period wave, such as the seas of Nigeria, Mauritania Friendship Port, Indonesia's Java Island, and Chile, etc. In these sea areas, the waves have these characteristics: the period is long, the wave height is not high but the penetrating power is strong, and the energy in the waves is high, which often leads to the severe six-degree-of-freedom (6-DOF) motion of the TSHD under the force of wave. During the operation, the drag arm and the drag head of the TSHD are connected to the hull through hoses. The wave compensator can play some effect on the seakeeping in order to resist the large ship oscillation of the TSHD under severe sea conditions, but the wave compensator have limits in the maximum travel. During the operation, if the motion of the drag head and the drag arm exceeds the safety limit of the wave compensator, it will pose a serious threat to the operation safety of the TSHD.
