Advanced Mooring Analysis – Matarani Port, Peru

Abstract: Terminal Internacional Del Sur S.A. (TISUR) is undertaking a port expansion project at Matarani Port, Peru. This terminal is the primary deep-water port for southern Peru, and the planned expansion includes improvements to the existing vessel berth, along with provision of an additional vessel berth.
The Matarani Port is situated on the coast of Peru and is subject to moderate swell activity. Prevailing wave conditions are incident from a relatively narrow band of directions. However, the wave action is complicated by the steep rock shoreline that reflects wave energy and the presence of a small island that provides negligible blocking and changes wave directions, thereby inducing complex wave pattern that affects moored vessels.
The purpose of this project was to evaluate ways to improve the mooring performance at the existing berth and make recommendations for the best approach to design a second berth. Possible solutions included extending the existing breakwater and installing constant tension mooring devices. Given the complexity of the mooring environment, the project team used both numerical models and physical models to analyze the mooring performance. This paper presents the overall project, including design elements, numerical modeling, and a brief statement of the physical modeling program (companion paper).
A Boussinesq wave model was used to evaluate the waves in the berth area, including the impacts of various breakwater configurations and reflective characteristics of the proposed dredge pocket. Because of the water depth, however, the length of breakwater that would be economically feasible is limited. Thus, the team recognized that even with an optimized breakwater, wave conditions at the berth would still present significant challenges for the mooring system.
Numerical modeling was also used as an initial tool to evaluate the performance of the mooring system using the MIKE MA mooring analysis module. The numerical model provided a way to simulate the mooring performance in a reflective wave environment and to test the performance of constant tension mooring devices on the berth. However, even with the fidelity of the numerical tools available, the project team was concerned that the models would not fully capture the resonance effects of the reflection of the swell waves in the vicinity of the berth. The team considered how to establish greater confidence in the design.
A 1:45 scale physical model of the Matarani Port area was developed at the NRC laboratory in Ottawa, Canada. The physical model domain included islands and nearshore bathymetric features that would refract, diffract, and reflect waves approaching the project, including the breakwater. The marine terminal structures and vessels were created at the same scale, with fenders and mooring lines carefully prepared to replicate the performance characteristics of the full-scale mooring system.
Using both the physical and numerical modeling efforts, the project team was able to optimize the design of the breakwater and make recommendations regarding the use of constant tension mooring devices. This project provides an example of how numerical and physical modeling can be used to complement each other.

How does this project / topic contribute to the advancement of the industry and profession?: The use of physical models is often considered to be excessive and expensive. While physical models can be excessive, when complemented with numerical modelling, they can provide significant value optimizing the solution of complex problems. This paper demonstrates a case where physical and numerical models were used to evaluate a mooring system in complex swell wave conditions. The study provided valuable input to the project and can provide some perspective about how methods like this could be used in future projects.

Does the project / topic implement new and innovative techniques, materials, technologies, and delivery methods?: The use of physical model testing for analyzing active mooring systems is innovative, and in this case, provided significant value to the project.

What was the most challenging aspect of your project / topic and how did you handle it to ensure success?: Both physical and numerical modeling of the active mooring systems were complex. The standard information/setup received from vendors regarding the performance characteristics had to be modified and improved to achieve the expected performance, and the project required significant effort to understand and model the characteristics of these systems.

Who is the target audience for this paper?: This paper is intended to assist engineers and port owners to understand the analysis methods available for complex mooring scenarios, which are becoming more frequent in port development. In particular, this paper would be helpful for anyone facing complex wave patterns or who has or should consider whether physical model testing would benefit their project.