The present entire pipe system consists of a very long vertical pipe with elastic joints, pin-joining the buffer (mass) at its bottom end to a much shorter horizontal pipe. Opposite end of the horizontal pipe is pin-joined to a vehicle maneuvering on the seafloor, and it can be subject to the planar (x, y) motion of the seafloor vehicle. The motion of the horizontal pipe can be restrained by the motion of the seafloor vehicle, requiring more elaborate computational modeling of the joints and the entire pipe system. Thrust vectors are applied to the elastic joints on the vertical pipe and the pin joints of the horizontal pipe. Elastic joints on the vertical pipe were previously modeled by 2 computational methods: the mass-spring elements (MSE) and finite elements (FEM). As the pin joint allows the horizontal pipe to rotate about the vertical axis, the entire pipe system has one zero eigenvalue associated with the rigid-body modes. Thus, the shift technique is utilized to solve the zero-eigenvalue problem. Moreover, the weight, generating the internal axial force of the vertical pipe, influences the eigenvalues of the entire system. Preliminary results indicate that the accuracy and advantages of the MSE modeling over FEM are more obvious for the entire system than for the previous vertical pipe system alone, and the two models are compared with numerical examples in Part II.
Recently, new researchers in developing deep-ocean mining pipe systems tend to prefer a self-propelled, seafloor vehicle ("miner" or "collector") to operate at 800–6000-m depth, that is similar to those of Chung and Chung et al. (1980–1997). This will likely lead to change in the pipe-to-miner link connecting systems for water-solid transport, similar to that of Chung, Whitney and Loden (1980) and Cheng and Chung, 1995)(Fig. 1).
