Linear maritime engineering structures are exposed to the highest levels of risk in the construction industry, because of the serial work involved in their design and construction. Systematic design or execution errors can turn these constructions into vulnerable artefacts. At the same time, the economic drive is pushing the long linear structures towards limited levels of redundancy, where failure of individual elements can generate progressive collapse. A global approach to risk is therefore indispensable in the management of coastal engineering projects, in addition to the organization of appropriate quality control systems. Awareness has indeed grown that a second performance layer on top of the classic quality control systems is needed to cope with these challenges. Apart from the help that can be expected from working at the level of standardisation, progress is mostly expected from measures which instigate project professionalism and collaboration between the different building partners.
The intervention of an independent organization within the framework of this risk management – a well-known traditional concept in many European countries – is an added value in a global risk management of maritime structures. A typical principle that has arisen from this approach is the strife for structural redundancy, even in the most slender and economic of structures. Dealing with uncertainty in an explicit way is another. The TIS (Technical Inspection Services) play a driving role in the constant review of the risk level within the dynamic risk management environment of a construction project. This can be done in a qualitative or in a quantitative way, depending on the nature and the severity of the risk. The externalization and independency of the service can make for a practical tool to assist in managing the technical project risks and transfer to all parties around the table the necessary confidence in the design and construction process, as well as promote dispute resolution around acceptable technical solutions and innovative alternatives within projects.
Provided the company providing TIS (Technical Inspection Services) has the necessary credentials, such global approach to risk management may give access to long term insurance schemes for latent or hidden defects (LDI or IDI, Latent or Inherent Defect Insurance), covering all building actors in the project jointly in an umbrella policy.
Apart from a recap into the principles of risk management and its application to different types of port infrastructure projects, the article will focus on the introduction of this traditional European concept in the Latin American environment, through a case study of a maritime port project in the port of Montevideo, Uruguay.
The article will be propose a classification of different types of quay walls according to their level of structural redundancy and their vulnerability to lack of tightness of the joints. It is explained how these walls range between structures with excellent redistribution capacity and great possibilities to perform complete visual verification of the soil tightness of the joints on the one hand side and structures that provide none of that on the other hand. Several real projects will be run through in the article and their classification according to the proposed system will be discussed. It will be examined how it is possible to upgrade the classification of a structure with specific interventions. It will also be shown that, in creating structural redundancy, the existence of ductility may be of the utmost importance. Elastic and plastic elongation may need to be generated to mobilize the required redistribution.
The project focused on more in detail, concerns a quay wall under construction in the port of Montevideo, Uruguay. An alternative calculation model set up independently from the black box model used by the designers, has been used as part of the technical inspection services to establish the sensitivity of the deck-on-pile structure to different sets of load combinations. It has been confirmed that the resistance to the horizontal loads for these type of structures can relatively easily be increased and tuned to the requirements, primarily by efficiently intervening in the connection node of the landward pile row (the one with the most limited free length) at marginal cost.
The alternative model has been used as part of a risk analysis, which has been able to identify and prioritize technical risks, as well as list mitigation measures for each of them, allowing for assistance in the technical management of the project.
The reanalysis of the structure, taking into account the geotechnical uncertainty of the conglomerate subsoil, also showed that a redistribution of the total projected concrete volume of the piles over the 4 pile rows, without any additional concrete consumption, could contribute to an important relief of the geotechnical risk.
Apart from a sound independent desktop analysis, a complete dynamic risk management process also necessarily includes inspection of the site construction process, a process which is currently ongoing for the reference project discussed. Experiences with it will be available and shared for the final article.